Distribution patterns of Calonectria (Ascomycota, Sordariomycetes, Hypocreales, Nectriaceae) species complexes related to diseased leaves and soil habitats during leaf blight outbreak season in Eucalyptus plantations in southern China

Abstract

Calonectria leaf blight caused by Calonectria species is one of the most important diseases associated with Eucalyptus plantations in Asia and South America. This study aimed to clarify the distribution patterns of Calonectria species residing in different species complexes associated with diseased trees and soils during leaf blight outbreak season in Eucalyptus plantations in southern China. In this study, 482 Calonectria isolates obtained from diseased Eucalyptus trees and soils under these trees in eight sampling sites in three provinces were identified by DNA sequence analyses of tef1, tub2, cmdA, and his3 gene regions. Six species residing in three species complexes were identified: Calonectriapseudoreteaudii and C.acaciicola in the Calonectriareteaudii species complex; C.hongkongensis, C.aconidialis, and C.chinensis in C.kyotensis species complex; and C.auriculiformis in C.cylindrospora species complex. The habitats of Calonectria in different species complexes differed, C.reteaudii species complex inhabits in both diseased trees and soils, C.kyotensis species complex only in soils. The Calonectria leaf blight in the sampled regions was caused by species in the C.reteaudii species complex but not by the species in the C.kyotensis species complex. These findings suggest that the species in the C.reteaudii species complex should receive more attention in disease management, as they are the primary cause of the disease in the sampled regions.

Introduction

The eucalypts, commonly known as gum trees, include the genera Angophora, Corymbia, and Eucalyptus, with more than 800 species, of which Eucalyptus spp. are the most numerous (Thornhill et al. 2019). Eucalyptus species are widely cultivated as commercial trees in Southeast Asia, Brazil, China, Australia, India, Europe, and South Africa due to their ability of fast-growing, adaptability, and versatility (Xie and Du 2019). In China, Eucalyptus plantations cover an area of approximately 5.46 million hm², accounting for approx. 2.5% of the country’s total forest area, and provide one-third of the country’s timber production (Xie et al. 2017; Xie and Du 2019).

The Eucalyptus leaf blight, caused by Calonectria spp., is considered one of the most severe diseases affecting Eucalyptus plantations, especially in Asia and South America (Crous 2002; Rodas et al. 2005; Alfenas et al. 2015; Pham et al. 2019, 2022a, 2022b; Wang and Chen 2020; Li et al. 2023a; Liang et al. 2023). The disease initially presents as water-soaked and light gray lesions of the middle and lower leaves. As it rapidly spreads, the lesions progress to light brown color and cover a significant portion of the leaf blade, ultimately leading to defoliation and even the death of the entire tree under highly favorable environmental conditions (Old et al. 2003; Rodas et al. 2005; Wang and Chen 2020; Wu and Chen 2021; Liang et al. 2023).

Severe outbreaks of Calonectria leaf blight have significantly impacted the growth of Eucalyptus plantations in southern China, resulting in substantial economic losses (Zhou and Wingfield 2011; Wang and Chen 2020; Wu and Chen 2021; Li et al. 2023a; Liang et al. 2023). The disease was initially observed in an Eucalyptus nursery located in Hainan Province in 1985, which resulted in significant mortality among Eucalyptus seedlings (Feng and Zheng 1986). In recent years, leaf blight caused by Calonectria species has been observed and confirmed in plantation in Fujian, Guangdong, Guangxi, and Hainan Provinces (Chen et al. 2013; Wang and Chen 2020; Wu and Chen 2021; Li et al. 2023b; Liang et al. 2023). The Calonectria species that are frequently isolated from diseased Eucalyptus trees in China include C.acaciicola, C.pseudoreteaudii, and C.queenslandica (Wang and Chen 2020; Wu and Chen 2021; Li et al. 2023a; Liang et al. 2023).

Calonectria has been detected not only in Eucalyptus tissues (mainly from tree leaves, as well as tree shoots and seedling stems) but also in soils under diseased trees and seedlings in China (Li et al. 2017, 2023a; Wang and Chen 2020; Liang et al. 2023). Presently, 26 Calonectria species associated with Eucalyptus have been identified and reported, including 19 species isolated from diseased leaves, 17 species isolated from soils associated with Eucalyptus, and 10 species isolated from both diseased tissues and soils associated with Eucalyptus (Lombard et al. 2010c; Li et al. 2017; Liu et al. 2020, 2021; Wu and Chen 2021; Zhang et al. 2022; Liang et al. 2023; Liu and Chen 2023).

Calonectria species have been frequently isolated from diseased Eucalyptus trees and soils in their plantations (Liu et al. 2020, 2021; Wu and Chen 2021; Li et al. 2023b; Liu and Chen 2023). However, only two studies were conducted to understand the species diversity and distribution characteristics of Calonectria, both from diseased plantation Eucalyptus trees and soils under these trees (Wu and Chen 2021; Li et al. 2023b). These studies were conducted solely in one Eucalyptus plantation (Wu and Chen 2021), or in a limited number of sampling regions, and there are significant differences in the number of samples between diseased trees and the soil under these trees (Li et al. 2023b). As a result, the distribution patterns of Calonectria species associated with diseased Eucalyptus trees and soils under these trees are still unclear. The purpose of this study was to comprehensively understand the distribution characteristics of Calonectria species related to diseased leaves and soil habitats during leaf blight outbreak season in Eucalyptus plantations in southern China. This was achieved by systematically procuring sampled collections of Calonectria from eight Calonectria leaf blight outbreak Eucalyptus plantations in three provinces in southern China.

Materials and methods

Disease survey, sample collection, and fungal isolation

In September 2021, we conducted several extensive surveys of the disease caused by Calonectria species in E.urophylla hybrid plantations in Guangdong, Guangxi, and Hainan Provinces in southern China. After the surveys, eight plantations were selected for sampling (Fig. 1). At each of the eight plantations, the trees were one-year-old, and the disease of Calonectria leaf blight occurred for about a month. The disease symptoms of Calonectria leaf blight were observed on 60%–80% of trees in each plantation (Fig. 2A, B) typically included leaf spots and blight (Fig. 2C), which resulted in defoliation (Fig. 2D). Depending on the plantation area, a number of diseased trees were selected for diseased leaf sampling. These trees were randomly distributed across each plantation. Three to five fresh symptomatic leaves were collected from each sampled tree. The same number of soil samples was collected under it from the upper 0–20 cm soil profile by removing the thick layer of leaf litter, as described by Liu and Chen (2023). The diseased leaf and soil samples were taken to our laboratory for further study.

Figure 1.

Locations of the eight sampled plantations in the Guangxi (sites A, B, C, D), Guangdong (sites E, F, G), and Hainan (site H) provinces in southern China.

Figure 2.

Diseased leaves and soil samples at plantations of a Eucalyptusurophylla hybrid in southern China A, B leaf spot and blight caused by Calonectria species were observed on 60%–80% of the trees in the plantations C blighted and dried dead leaves D leaves that were dying and drying, resulting in defoliation in the plantation.

To induce Calonectria sporulation on leaf samples, one diseased leaf of each sampled tree with typical symptoms of Calonectria leaf blight was selected for incubation in a moist petri dish chamber at room temperature until the conidiophores were observed. The development of Calonectria strains in soil samples was induced by using Medicagosativa (alfalfa) seeds, as described by Liu and Chen (2023). The single conidia from conidial masses of Calonectria that sporulated from the diseased leaf or soil samples were transferred to 2% (v/v) malt extract agar (MEA) also following Wu and Chen’s protocol (2023). One isolate with typical morphological characteristics of the conidiophores of Calonectria, was isolated from each diseased leaf sample or soil sample. Occasionally, two Calonectria isolates were isolated from each sample when the isolates with different morphological vesicles were observed. All obtained single conidium cultures were deposited in the Culture Collection (CSF) at the Research Institute of Fast-growing Trees (RIFT), Chinese Academy of Forestry (CAF), Zhanjiang, Guangdong Province, China.

DNA extraction, PCR amplification, and sequencing

The obtained Calonectria isolates were cultivated in a 2% MEA medium for a week at room temperature for total genomic DNA extraction. The mycelia were scraped from the cultures. The total genomic DNA of each isolate was extracted using the cetyltrimethylammonium bromide (CTAB) method, as described by van Burik et al. (1998). Four gene regions, namely the translation elongation factor 1-alpha (tef1), β-tubulin (tub2), calmodulin (cmdA), and histone H3 (his3), were amplified using the primer pairs and PCR protocols described by Liu et al. (2020). All PCR products were Sanger sequenced in both directions by the same primers used for PCR amplification. The PCR products were sequenced by the Beijing Genomics Institute, Guangzhou, China. All initial sequences were edited using Geneious v.7.1.8 (Kearse et al. 2012). The sequences obtained in this study were deposited in GenBank (http://www.ncbi.nlm.nih.gov).

Phylogenetic analyses

The tef1 and tub2 regions were sequenced for all Calonectria isolates selected for identification in the current study. All these isolates were preliminarily identified through standard nucleotide BLAST searches in the NCBI database (https://blast.ncbi.nlm.nih.gov/) using the tef1 and tub2 sequences. Based on their preliminary identification, representative isolates were selected for sequencing the additional gene regions of cmdA and his3. Based on the combined genotype of tef1, tub2, cmdA, and his3 sequences, representative isolates presenting all genotypes obtained in this study were used for molecular identification. Sequences of the isolates from the type specimens of all the published species in the preliminarily identified Calonectria species complexes were used for phylogenetic analyses. The sequence datasets were aligned using online MAFFT v. 7 (http://mafft.cbrc.jp/alignment/server/) with the FFT-NS-i strategy (slow; interactive refinement method) (Katoh and Standley 2013). The aligned sequence datasets were manually edited and cut using MEGA v. 7.0 software (Kumar et al. 2016).

The sequence datasets of each gene region and the combination of four gene regions were performed on Maximum likelihood (ML) and Bayesian inference (BI) phylogenetic analyses using CIPRES Science Gateway v. 3.3. For the BI analyses, the most suitable models of the five sequence databases were carried through the jModelTest v. 2.1.5 (Posada 2008). Both ML and BI analyses were completed using online software, RaxML v. 8.2.12 (Stamatakis 2014) and MrBayes. v. 3.2.7 (Ronquist et al. 2012), respectively, as described by Wu and Chen (2023). Phylogenetic trees were viewed via FigTree v 1.4.2 and MEGA v. 7 for BI and ML trees, respectively.

Results

Sample collection and fungal isolation

After a comprehensive collection of samples across eight sites (A–H) in Guangdong, Guangxi, and Hainan Provinces of southern China, a total of 802 samples were collected. These included 401 diseased leaf samples from 401 trees, and 401 soil samples (Table 1, Figs 1, 2). At each sampling site, 39–62 diseased leaf samples, and the same number of soil samples were collected.

Table 1.

The number of samples and Calonectria spp. obtained from Eucalyptus plantations at eight sampling sites.

Site code	Diseased leaf samples						Soil samples
	Total number of diseased leaf samples	No. of samples which yielded Calonectria	Total number of Calonectria isolates	No. of Calonectria isolates which selected for sequencing	No. of C.pseudoreteaudii isolates	No. of C.acaciicola isolates	Total number of soil samples	No. of samples obtained Calonectria	Total number of Calonectria isolates	No. of Calonectria isolates which selected for sequencing	No. of C.pseudoreteaudii isolates	No. of C.acaciicola isolates	No. of C.hongkongensis isolates	No. of C.aconidialis isolates	No. of C.chinensis isolates	No. of C.auriculiformis isolates
A	62	61	61	20	20	0	62	47	53	26	20	0	0	6	0	0
B	50	50	50	50	50	0	50	19	19	19	19	0	0	0	0	0
C	50	50	50	20	20	0	50	34	35	21	20	0	0	1	0	0
D	50	50	50	50	50	0	50	30	31	31	29	0	2	0	0	0
E	50	50	50	50	50	0	50	26	26	26	25	0	0	0	0	1
F	39	39	39	20	20	0	39	5	5	5	5	0	0	0	0	0
G	50	49	49	20	20	0	50	1	1	1	1	0	0	0	0	0
H	50	50	54	54	33	21	50	50	69	69	29	21	14	0	5	0
Total	401	399	403	284	263	21	401	212	239	198	148	21	16	7	5	1

Calonectria isolates were obtained from leaf samples from the diseased trees from the eight sampling sites, except for one of the 62 samples from site A and one of the 50 samples from site G. The proportion of diseased leaf samples successfully obtained from Calonectria ranged from 98% to 100% for the eight sampling sites (avg. 99.5%). Each isolate was obtained from a single Calonectria diseased leaf sample, except for 54 Calonectria isolates from 50 such samples at site H. This is because four diseased leaf samples at site H exhibited differing vesicle morphologies, therefore, two isolates were obtained from each of them (Table 1).

A relatively large proportion of Calonectria isolates were obtained from the soil samples from the eight sites, except for sites F and G (Guangdong Province). The proportion of soil samples with Calonectria ranged from 2% (site G) to 100% (site H) (avg. 51.1%). Each isolate was obtained from a single Calonectria soil sample at sites B, E, F, and G, while more than one isolate was obtained from some of the soil samples at the sites A, C, D, and H where isolates with different morphologies of the conidia or vesicles were observed (Table 1).

In total, 642 isolates with typical morphological characteristics of Calonectria were obtained. These included 403 isolates from the 401 diseased leaf samples and 239 isolates from the 401 soil samples (Table 1).

Sequencing

Calonectria isolates were obtained from a relatively large proportion of the samples, from both the diseased trees and soils, at sites A, B, C, D, E, and H. All isolates from sites B, D, E, and H were sequenced. Since sites A, and C are relatively near to B, and D, only partial isolates obtained from diseased trees and soils at sites A, and C were sequenced. Since Calonectria was obtained from a small proportion of the soil samples at sites F, and G, all the isolates obtained from soils, and partial isolates obtained from diseased trees at the two sites were sequenced (Table 1). In total, 482 isolates were used to sequence the tef1 and tub2 gene regions (Table 1, Suppl. material 1). This included 54 isolates that were also identified by Liang et al. (2023) (Suppl. material 1). Based on the combined genotypes of the tef1 and tub2 gene sequences, and the sampling source, 169 isolates were selected for further sequencing of the cmdA and his3 gene regions (Suppl. material 1). A total of 18 genotypes were generated based on the sequences of the tef1, tub2, cmdA, and his3 regions of the 169 isolates that allowed for their identification. The remaining 313 isolates were identified based on tef1 and tub2 gene regions exclusively.

Phylogenetic analyses

To analyze their phylogenetic relationships, one or two isolates representing single genotype were selected that resulted in selection of 29 isolates representing 18 genotypes in total (Suppl. material 1). Additionally, the sequences from 90 isolates, including all ex-type isolates of all the Calonectria species of their respective species complexes, corresponding to 52 published Calonectria species, were retrieved from GenBank (Table 2). These sequences were used in phylogenetic analyses of the four individual gene regions and a combination of them.

Table 2.

Calonectria spp. isolates from the published studies used for phylogenetic analyses in this study.

Species code a	Species	Isolates no. b, c	Other collection number c	Substrate/host	Area of occurrence	Collector	GenBank accession numbers d				References of source of the isolates/sequencing data
							cmdA	his3	tef1	tub2
B1	C.acaciicola	CMW 47173T	CBS 143557	Soil (Acaciaauriculiformis plantation)	Do Luong, Nghe An, Vietnam	N.Q. Pham and T.Q. Pham	MT335160	MT335399	MT412690	MT412930	Pham et al. 2019; Liu et al. 2020
		CMW 47174	CBS 143558	Soil (A.auriculiformis plantation)	Do Luong, Nghe An, Vietnam	N.Q. Pham and T.Q. Pham	MT335161	MT335400	MT412691	MT412931	Pham et al. 2019; Liu et al. 2020
B2	C.acicola	CMW 30996T	–	Phoenixcanariensis	Northland, New Zealand	H. Pearson	MT335162	MT335401	MT412692	MT412932	Gadgil and Dick 2004; Lombard et al. 2010a; Liu et al. 2020
		CBS 114812	CMW 51216	P.canariensis	Northland, New Zealand	H. Pearson	MT335163	MT335402	MT412693	MT412933	Gadgil and Dick 2004; Lombard et al. 2010a; Liu et al. 2020
B4	C.aconidialis	CMW 35174T	CBS 136086; CERC 1850	Soil (Eucalyptus plantation)	Hainan, China	X. Mou and S.F. Chen	MT335165	MT335404	MT412695	OK357463	Lombard et al. 2015a; Liu et al. 2020, 2021
		CMW 35384	CBS 136091; CERC 1886	Soil (Eucalyptus plantation)	Hainan, China	X. Mou and S.F. Chen	MT335166	MT335405	MT412696	OK357464	Lombard et al. 2015a; Liu et al. 2020, 2021
B5	C.aeknauliensis	CMW 48253T	CBS 143559	Soil (Eucalyptus plantation)	Aek Nauli, North Sumatra, Indonesia	M.J. Wingfield	MT335180	MT335419	MT412710	OK357465	Pham et al. 2019; Liu et al. 2020, 2021
		CMW 48254	CBS 143560	Soil (Eucalyptus plantation)	Aek Nauli, North Sumatra, Indonesia	M.J. Wingfield	MT335181	MT335420	MT412711	OK357466	Pham et al. 2019; Liu et al. 2020, 2021
B8	C.asiatica	CBS 114073T	CMW 23782; CPC 3900	Debris (leaf litter)	Prathet Thai, Thailand	N.L. Hywel-Jones	AY725741	AY725658	AY725705	AY725616	Crous et al. 2004; Lombard et al. 2010a
B9	C.auriculiformis	CMW 47178T	CBS 143561	Soil (A.auriculiformis plantation)	Hau Loc, Thanh Hoa, Vietnam	N.Q. Pham and T.Q. Pham	MT335190	MT335430	MT412721	MT412944	Pham et al. 2019; Liu et al. 2020
		CMW 47179	CBS 143562	Soil (A.auriculiformis plantation)	Hau Loc, Thanh Hoa, Vietnam	N.Q. Pham and T.Q. Pham	MT335191	MT335431	MT412722	MT412945	Pham et al. 2019; Liu et al. 2020
B10	C.australiensis	CMW 23669T	CBS 112954; CPC 4714	Ficuspleurocarpa	Queensland, Australia	C. Pearce and B. Paulus	MT335192	MT335432	MT412723	MT412946	Crous et al. 2006; Lombard et al. 2010a; Liu et al. 2020
B14	C.brasiliensis	CBS 230.51T	IMI 299576	Eucalyptus sp.	Ceara state, Brazil	T.R. Ciferri	MT335200	MT335440	MT412731	MT412953	Batista 1951; Crous 2002; Lombard et al. 2010b; Liu et al. 2020
		CMW 32949	CBS 114257; CPC 1944	Eucalyptus sp.	Aracruz, Brazil	A.C. Alfenas	MT335201	MT335441	MT412732	MT412954	Lombard et al. 2010a; Liu et al. 2020
B17	C.brassicicola	CBS 112841T	CMW 51206; CPC 4552	Soil at Brassica sp.	Indonesia	M.J. Wingfield	KX784561	N/A	KX784689	KX784619	Lombard et al. 2016
B19	C.bumicola	CMW 48257T	CBS 143575	Soil (Eucalyptus plantation)	Aek Nauli, North Sumatra, Indonesia	M.J. Wingfield	MT335205	MT335445	MT412736	OK357467	Pham et al. 2019; Liu et al. 2020, 2021
B20	C.canadiana	CMW 23673T	CBS 110817; STE-U 499	Picea sp.	Canada	S. Greifenhagen	MT335206	MT335446	MT412737	MT412958	Kang et al. 2001b; Crous 2002; Lechat et al. 2010; Liu et al. 2020
		CERC 8952	–	Soil	Henan, China	S.F. Chen	MT335290	MT335530	MT412821	MT413035	Liu and Chen 2017; Liu et al. 2020
B22	C.cerciana	CMW 25309T	CBS 123693	E.urophylla × E.grandis hybrid cutting	CERC nursery, Guangdong, China	M.J. Wingfield and X.D. Zhou	MT335211	MT335451	MT412742	MT412963	Lombard et al. 2010c; Liu et al. 2020
		CMW 25290	CBS 123695	E.urophylla × E.grandis hybrid cutting	CERC nursery, Guangdong, China	M.J. Wingfield and X.D. Zhou	MT335212	MT335452	MT412743	MT412964	Lombard et al. 2010c; Liu et al. 2020
B23	C.chinensis	CMW 23674T	CBS 114827; CPC 4101	Soil	Hong Kong, China	E.C.Y. Liew	MT335220	MT335460	MT412751	MT412972	Crous et al. 2004; Lombard et al. 2010a; Liu et al. 2020
		CMW 30986	CBS 112744; CPC 4104	Soil	Hong Kong, China	E.C.Y. Liew	MT335221	MT335461	MT412752	MT412973	Crous et al. 2004; Lombard et al. 2010a; Liu et al. 2020
B26	C.cochinchinensis	CMW 49915T	CBS 143567	Soil (Heveabrasiliensis plantation)	Duong Minh Chau, Tay Ninh, Vietnam	N.Q. Pham, Q.N. Dang and T.Q. Pham	MT335225	MT335465	MT412756	MT412977	Pham et al. 2019; Liu et al. 2020
		CMW 47186	CBS 143568	Soil (A.auriculiformis plantation)	Song May, Dong Nai, Vietnam	N.Q. Pham and T.Q. Pham	MT335226	MT335466	MT412757	MT412978	Pham et al. 2019; Liu et al. 2020
B29	C.colombiensis	CMW 23676T	CBS 112220; CPC 723	Soil (E.grandis trees)	La Selva, Colombia	M.J. Wingfield	MT335228	MT335468	MT412759	MT412980	Crous et al. 2004; Liu et al. 2020
		CMW 30985	CBS 112221; CPC 724	Soil (E.grandis trees)	La Selva, Colombia	M.J. Wingfield	MT335229	MT335469	MT412760	MT412981	Crous et al. 2004; Liu et al. 2020
B30	C.crousiana	CMW 27249T	CBS 127198	E.grandis	Fujian, China	M.J. Wingfield	MT335230	MT335470	MT412761	MT412982	Chen et al. 2011; Liu et al. 2020
		CMW 27253	CBS 127199	E.grandis	Fujian, China	M.J. Wingfield	MT335231	MT335471	MT412762	MT412983	Chen et al. 2011; Liu et al. 2020
B31	C.curvispora	CMW 23693T	CBS 116159; CPC 765	Soil	Tamatave, Madagascar	P.W. Crous	MT335232	MT335472	MT412763	OK357468	Victor et al. 1997; Crous 2002; Lombard et al. 2010a, 2015a; Liu et al. 2020, 2021
		CMW 48245	CBS 143565	Soil (Eucalyptus plantation)	Aek Nauli, North Sumatra, Indonesia	M.J. Wingfield	MT335233	MT335473	MT412764	N/A e	Pham et al. 2019; Liu et al. 2020
B32	C.cylindrospora	CBS 119670	CMW 51310; CPC 12766	Pistacialentiscus	Italy	N/A	MT335236	MT335476	MT412767	MT412985	Lombard et al. 2015a, 2015b, 2016; Liu et al. 2020
		CMW 30978	CBS 110666; P90.1479; STE-U 497	Ilexvomitoria	Florida, USA	N.E. El-Gholl	MT335237	MT335477	MT412768	MT412986	Crou 2002; Lombard et al. 2010a, 2015b; Liu et al. 2020
B44	C.hawksworthii	CBS 111870T	CMW 51194; CPC 2405	Nelumbonucifera	Pamplemousses garden, Mauritius	A. Peerally	MT335254	MT335494	MT412785	MT413003	Crous 2002; Liu et al. 2020
		CMW 31393	CBS 136641	E.urophylla × E.grandis	Guangxi, China	X. Zhou and G. Zhao	MT335247	MT335487	MT412778	MT412996	Lombard et al. 2015a; Liu et al. 2020
B46	C.heveicola	CMW 49913T	CBS 143570	Soil (Heveabrasiliensis plantation)	Bau Bang, Binh Duong, Vietnam	N.Q. Pham, Q.N. Dang and T.Q. Pham	MT335255	MT335495	MT412786	MT413004	Pham et al. 2019; Liu et al. 2020
		CMW 49928	CBS 143571	Soil	Bu Gia Map National Park, Binh Phuoc, Vietnam	N.Q. Pham, Q.N. Dang and T.Q. Pham	MT335280	MT335520	MT412811	MT413025	Pham et al. 2019; Liu et al. 2020
B48	C.hongkongensis	CBS 114828T	CMW 51217; CPC 4670	Soil	Hong Kong, China	M.J. Wingfield	MT335258	MT335498	MT412789	MT413007	Crous et al. 2004; Liu et al. 2020
		CERC 3570	CMW 47271	Soil (Eucalyptus plantation)	Beihai, Guangxi, China	S.F. Chen,J.Q. Li and G.Q. Li	MT335260	MT335500	MT412791	MT413009	Li et al. 2017; Liu et al. 2020
B51	C.ilicicola	CMW 30998T	CBS 190.50; IMI 299389; STE-U 2482	Solanumtuberosum	Bogor, Java, Indonesia	K.B. Boedijn and J. Reitsma	MT335266	MT335506	MT412797	OK357469	Boedijn and Reitsma 1950; Crous 2002; Lombard et al. 2010a; Liu et al. 2020, 2021
B52	C.indonesiae	CMW 23683T	CBS 112823; CPC 4508	Syzygiumaromaticum	Warambunga, Indonesia	M.J. Wingfield	MT335267	MT335507	MT412798	MT413015	Crous et al. 2004; Liu et al. 2020
		CBS 112840	CMW 51205; CPC 4554	S.aromaticum	Warambunga, Indonesia	M.J. Wingfield	MT335268	MT335508	MT412799	MT413016	Crous et al. 2004; Liu et al. 2020
B54	C.insularis	CMW 30991T	CBS 114558; CPC 768	Soil	Tamatave, Madagascar	P.W. Crous	MT335269	MT335509	MT412800	MT413017	Schoch et al. 1999; Lombard et al. 2010a, 2016; Liu et al. 2020
		CMW 30992	CBS 114559; CPC 954	Soil	Conejos, Veracruz, Mexico	M.J. Wingfield	MT335270	MT335510	MT412801	MT413018	Lombard et al. 2010a, 2016; Liu et al. 2020
B55	C.kyotensis	CBS 114525T	ATCC 18834; CMW 51824; CPC 2367	Robiniapseudoacacia	Japan	T. Terashita	MT335271	MT335511	MT412802	MT413019	Terashita 1968; Crous 2002; Lombard et al. 2016; Liu et al. 2020
		CBS 114550	CMW 51825; CPC 2351	Soil	China	M.J. Wingfield	MT335246	MT335486	MT412777	MT412995	Lombard et al. 2016; Liu et al. 2020
B56	C.lageniformis	CBS 111324T	CMW 51177; CPC 1473	Leaf of Eucalyptus sp.	Rivière Noire, Mauritius	H. Smith	KX784574	N/A	KX784702	KX784632	Lombard et al. 2016; Marin-Felix et al. 2017
B57	C.lantauensis	CERC 3302T	CBS 142888; CMW 47252	Soil	Lidao, Hong Kong, China	M.J. Wingfield and S.F. Chen	MT335272	MT335512	MT412803	OK357470	Li et al. 2017; Liu et al. 2020, 2021
		CERC 3301	CBS 142887; CMW 47251	Soil	Lidao, Hong Kong, China	M.J. Wingfield and S.F. Chen	MT335273	MT335513	MT412804	OK357471	Li et al. 2017; Liu et al. 2020, 2021
B58	C.lateralis	CMW 31412T	CBS 136629	Soil (Eucalyptus plantation)	Guangxi, China	X. Zhou, G. Zhao and F. Han	MT335274	MT335514	MT412805	MT413020	Lombard et al. 2015a; Liu et al. 2020
B63	C.lombardiana	CMW 30602T	CBS 112634; CPC 4233; Lynfield 417	Xanthorrhoeaaustralis	Victoria, Australia	T. Baigent	MT335395	MT335635	MT412926	MT413133	Crous 2002; Crous et al. 2006; Lombard et al. 2010c; Liu et al. 2020
B66	C.malesiana	CMW 23687T	CBS 112752; CPC 4223	Soil	Northern Sumatra, Indonesia	M.J. Wingfield	MT335286	MT335526	MT412817	MT413031	Crous et al. 2004; Liu et al. 2020
		CBS 112710	CMW 51199; CPC 3899	Leaf litter	Prathet, Thailand	N.L. Hywel-Jones	MT335287	MT335527	MT412818	MT413032	Crous et al. 2004; Liu et al. 2020
B67	C.maranhensis	CBS 134811T	LPF142	Eucalyptus sp. (leaf)	Açailandia, Maranhao, Brazil	A.C. Alfenas	KM396035	KM396118	KM395861	KM395948	Alfenas et al. 2015
		CBS 134812	LPF143	Eucalyptus sp. (leaf)	Açailandia, Maranhao, Brazil	A.C. Alfenas	KM396036	KM396119	KM395862	KM395949	Alfenas et al. 2015
B74	C.multiseptata	CMW 23692T	CBS 112682; CPC 1589	E.grandis	North Sumatra, Indonesia	M.J. Wingfield	MT335299	MT335539	MT412830	MT413044	Crous et al. 2004; Lombard et al. 2010a; Liu et al. 2020
B80	C.pacifica	CMW 16726T	A1568; CBS 109063; IMI 354528; STE-U 2534	Araucariaheterophylla	Hawaii, USA	M. Aragaki	MT335311	MT335551	MT412842	OK357472	Kang et al. 2001b; Crous 2002, Crous et al. 2004; Liu et al. 2020, 2021
		CMW 30988	CBS 114038	Ipomoeaaquatica	Auckland, New Zealand	C.F. Hill	MT335312	MT335552	MT412843	OK357473	Crous 2002; Crous et al. 2004; Lombard et al. 2010a; Liu et al. 2020, 2021
B86	C.penicilloides	CMW 23696T	CBS 174.55; STE-U 2388	Prunus sp.	Hatizyo Island, Japan	M. Ookubu	MT335338	MT335578	MT412869	MT413081	Tubaki 1958; Crous 2002; Liu et al. 2020
B89	C.plurilateralis	CBS 111401T	CMW 51178; CPC 1637	Soil	Ecuador	M.J. Wingfield	MT335340	MT335580	MT412871	MT413083	Lombard et al. 2016; Liu et al. 2020
B90	C.propaginicola	CBS 134815T	LPF220	Eucalyptus sp. (seeding)	Santana, Pará, Brazil	A.C. Alfenas	KM396040	KM396123	KM395866	KM395953	Alfenas et al. 2015
		CBS 134816	LPF222	Eucalyptus sp. (seeding)	Santana, Pará, Brazil	A.C. Alfenas	KM396041	KM396124	KM395867	KM395954	Alfenas et al. 2015
B97	C.pseudoreteaudii	CMW 25310T	CBS 123694	E.urophylla × E.grandis	Guangdong, China	M.J. Wingfield and X.D. Zhou	MT335354	MT335594	MT412885	MT413096	Lombard et al. 2010c; Liu et al. 2020
		CMW 25292	CBS 123696	E.urophylla × E.grandis	Guangdong, China	M.J. Wingfield and X.D. Zhou	MT335355	MT335595	MT412886	MT413097	Lombard et al. 2010c; Liu et al. 2020
B104	C.queenslandica	CMW 30604T	CBS 112146; CPC 3213	E.urophylla	Lannercost, Queensland, Australia	B. Brown	MT335367	MT335607	MT412898	MT413108	Kang et al. 2001a; Lombard et al. 2010c; Liu et al. 2020
		CMW 30603	CBS 112155; CPC 3210	E.pellita	Lannercost, Queensland, Australia	P.Q Thu and K.M. Old	MT335368	MT335608	MT412899	MT413109	Kang et al. 2001a; Lombard et al. 2010c; Liu et al. 2020
B106	C.reteaudii	CMW 30984T	CBS 112144; CPC 3201	E.camaldulensis	Chon Thanh, Binh Phuoc, Vietnam	M.J. Dudzinski and P.Q. Thu	MT335370	MT335610	MT412901	MT413111	Kang et al. 2001a; Crous 2002; Crous et al. 2006; Liu et al. 2020
		CMW 16738	CBS 112143; CPC 3200	Eucalyptus leaves	Binh Phuoc, Vietnam	M.J. Dudzinski and P.Q. Thu	MT335371	MT335611	MT412902	MT413112	Kang et al. 2001a; Crous 2002; Crous et al. 2006; Liu et al. 2020
B112	C.sumatrensis	CMW 23698T	CBS 112829; CPC 4518	Soil	Northern Sumatra, Indonesia	M.J. Wingfield	MT335382	MT335622	MT412913	OK357474	Crous et al. 2004; Liu et al. 2020, 2021
		CMW 30987	CBS 112934; CPC 4516	Soil	Northern Sumatra, Indonesia	M.J. Wingfield	MT335383	MT335623	MT412914	OK357475	Crous et al. 2004; Liu et al. 2020, 2021
B113	C.syzygiicola	CBS 112831T	CMW 51204; CPC 4511	Syzygiumaromaticum	Sumatra, Indonesia	M.J. Wingfield	N/A	N/A	KX784736	KX784663	Lombard et al. 2016
B115	C.tonkinensis	CMW 47430T	CBS 143576	Soil (Eucalyptus plantation)	Bavi, Hanoi, Vietnam	N.Q. Pham and T.Q. Pham	MT335384	MT335624	MT412915	MT413122	Pham et al. 2019; Liu et al. 2020
B116	C.uniseptata	CBS 413.67T	CMW 23678; CPC 2391; IMI 299577	Paphiopedilumcallosum	Celle, Germany	W. Gerlach	GQ267379	GQ267248	GQ267307	GQ267208	Lombard et al. 2016
B118	C.variabilis	CMW 3187T	AR2675; CBS 114677; CPC 2436	Scheffleramorototoni	Pará, Brazil	F.C. de Albuquerque	MT335392	MT335632	MT412923	MT413130	Crous et al. 1993; Crous 2002; Lombard et al. 2010a, 2016; Liu et al. 2020
		CMW 2914	CBS 112691; CPC 2506	Theobromagrandiflorum	Pará, Brazil	F. Carneiro	MT335393	MT335633	MT412924	MT413131	Crous et al. 1993; Crous 2002; Lombard et al. 2010a, 2016; Liu et al. 2020
B120	C.yunnanensis	CERC 5339T	CBS 142897; CMW 47644	Soil (Eucalyptus plantation)	Yunnan, China	S.F. Chen and J.Q. Li	MT335396	MT335636	MT412927	MT413134	Li et al. 2017; Liu et al. 2020
		CERC 5337	CBS 142895; CMW 47642	Soil (Eucalyptus plantation)	Yunnan, China	S.F. Chen and J.Q. Li	MT335397	MT335637	MT412928	MT413135	Li et al. 2017; Liu et al. 2020
B124	C.singaporensis	CBS 146715T	MUCL 048320	leaf litter (submerged in a small stream)	South East Asian rainforest, Mac Ritchie Reservoir, Singapore	C. Decock	MW890042	MW890055	MW890086	MW890124	Crous et al. 2021
		CBS 146713	MUCL 048171	leaf litter (submerged in a small stream)	South East Asian rainforest, Mac Ritchie Reservoir, Singapore	C. Decock	MW890040	MW890053	MW890084	MW890123	Crous et al. 2021
B127	C.borneana	CMW 50782T	CBS 144553	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635067	OL635043	OL635019	N/A	Pham et al. 2022a
		CMW 50832	CBS 144551	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635065	OL635041	OL635017	N/A	Pham et al. 2022a
B128	C.ladang	CMW 50776T	CBS 144550	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635075	OL635051	OL635027	N/A	Pham et al. 2022a
		CMW 50775	CBS 144549	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635074	OL635050	OL635026	N/A	Pham et al. 2022a
B129	C.pseudomalesiana	CMW 50821T	CBS 144563	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635076	OL635052	OL635028	OL635137	Pham et al. 2022a
		CMW 50779	CBS 144668	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635077	OL635053	OL635029	OL635138	Pham et al. 2022a
B130	C.tanah	CMW 50777T	CBS 144562	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635088	OL635064	OL635040	OL635146	Pham et al. 2022a
		CMW 50771	CBS 144560	Soil (Eucalyptus plantation)	Sabah, Tawau, Brumas, Malaysia	N.Q. Pham, Marincowitz and M.J. Wingfield	OL635086	OL635062	OL635038	OL635144	Pham et al. 2022a
B131	C.cassiae	ZHKUCC 210011 T	–	Cassiasurattensis	Guangzhou City, Guangdong, China	Y. X. Zhang, C. T. Chen, Manawas., and M. M. Xiang	ON260790	N/A	MZ516860	MZ516863	Zhang et al. 2022
		ZHKUCC 210012	–	Cassiasurattensis	Guangzhou City, Guangdong, China	Y. X. Zhang, C. T. Chen, Manawas., and M. M. Xiang	ON260791	N/A	MZ516861	MZ516864	Zhang et al. 2022
B132	C.guangdongensis	ZHKUCC 21-0062T	–	Heliconiametallica	Guangdong, China	Y. X. Zhang, C. T. Chen, Manawas., and M. M. Xiang	MZ491127	N/A	MZ491149	MZ491171	Zhang et al. 2022
		ZHKUCC 21-0063	–	Heliconiametallica	Guangdong, China	Y. X. Zhang, C. T. Chen, Manawas., and M. M. Xiang	MZ491128	N/A	MZ491150	MZ491172	Zhang et al. 2022
	Curvicladiellacignea	CBS 109167T	CPC 1595; MUCL 40269	Decaying leaf	French Guiana	C. Decock	KM231287	KM231461	KM231867	KM232002	Decock and Crous 1998; Crous et al. 2006; Lombard et al. 2015b
		CBS 109168	CPC 1594; MUCL 40268	Decaying seed	French Guiana	C. Decock	KM231286	KM231460	KM231868	KM232003	Decock and Crous 1998; Crous et al. 2006; Lombard et al. 2015b

^a Codes (B1–B120) of the 120 accepted Calonectria species accepted according to Liu et al. (2020). ^b T: ex-type isolates of the species. ^c AR: Amy Y. Rossman working collection; ATCC: American Type Culture Collection, Virginia, USA; CBS: Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands; CERC: China Eucalypt Research Centre, Zhanjiang, Guangdong Province, China; CMW: Culture collection of the Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa; CPC: Pedro Crous working collection housed at Westerdijk Fungal Biodiversity Institute; IMI: International Mycological Institute, CABI Bioscience, Egham, Bakeham Lane, UK; MUCL: Mycotheque, Laboratoire de Mycologie Systematique st Appliqee, I’Universite, Louvian-la-Neuve, Belgium; STE-U: Department of Plant Pathology, University of Stellenbosch, South Africa; ZHKUCC: Zhongkai University of Agriculture and Engineering Culture Collection; –: no other collection number. ^dtef1: translation elongation factor 1-alpha; tub2: β-tubulin; cmdA: calmodulin; his3: histone H3. ^e N/A: information is not available.

The sequenced isolates yielded approximately 500 bp for tef1, 560 bp for tub2, 680 bp for cmdA, and 430 bp for his3 gene regions. The model for each gene region was selected based on jModeltest v. 2.1.5. The TIM2+I+G, HKY+I+G, TrN+I+G, HKY+I+G, and TIM2+I+G models were selected for tef1, tub2, cmdA, his3, and the consolidated dataset, respectively. The topological structures generated from BI analyses were similar to those generated from ML analyses for each dataset. The ML trees displayed bootstrap values from ML and the posterior probabilities from BI are shown in Fig. 3, Suppl. materials 2–5.

Figure 3.

Phylogenetic tree of Calonectria species based on maximum likelihood (ML) analyses of a combined DNA dataset of tef1, tub2, cmdA, and his3 gene sequences. Bootstrap support values ≥ 70% for ML and posterior probability values ≥ 0.95 for Bayesian inference (BI) analyses are presented above the branches as ML/BI. Bootstrap values < 70% or probability values < 0.95 are marked with “*,” and absent analysis values are marked with “-”. Ex-type isolates are marked with “T.” Isolates sequenced in this study are highlighted in bold. The outgroup taxon was Curvicladiellacignea (CBS 109167 and CBS 109168).

The 29 Calonectria isolates were clustered into six distinct groups (Groups A–F) based on the phylogenetic analyses of the four gene regions’ combination (Fig. 3). Among them, isolates in Group A and Group B belong to the C.reteaudii complex. Isolates in Group A were clustered with or closely related to C.acaciicola, C.pseudoreteaudii, C.reteaudii, or C.guangdongensis in the tef1, cmdA, and his3 trees (Suppl. materials 2, 4, 5), and with C.acaciicola in the tub2 tree (Suppl. material 3). The tef1/tub2/cmdA/his3 tree confirmed that isolates in Group A were most closely related to C.acaciicola (Fig. 3), and thus they were accepted as belonging to this species. Isolates in Group B were clustered with, or most closely related to, C.pseudoreteaudii in each of the tef1, tub2, cmdA, his3, and tef1/tub2/cmdA/his3 trees (Fig. 3, Suppl. materials 2–5). Thus, isolates in Group B are referred as C.pseudoreteaudii.

Isolate CSF24816 (Group C) was grouped in the C.cylindrospora species complex (Fig. 3, Suppl. materials 2–5). It was clustered with C.auriculiformis in the tef1 tree, with C.cerciana in the tub2 tree, with C.cerciana and C.tonkinensis in the cmdA tree, and with C.auriculiformis, C.cerciana, and C.tonkinensis in the his3 tree (Suppl. materials 2–5). It was most closely related to C.auriculiformis in the tef1/tub2/cmdA/his3 tree (Fig. 3), thus the isolate CSF24816 was identified as C.auriculiformis.

Isolates in Groups D, E, and F resided in the C.kyotensis species complex based on the phylogenetic trees of tef1, tub2, cmdA, his3, and tef1/tub2/cmdA/his3 (Fig. 3, Suppl. materials 2–5). Isolates in Group D, Group E, and Group F were consistently clustered with or most closely related to C.chinensis, C.hongkongensis, and C.aconidialis, respectively (Fig. 3, Suppl. materials 2–5). Therefore, isolates in Group D, Group E, and Group F were identified as C.chinensis, C.hongkongensis and C.aconidialis, respectively.

Calonectria distribution associated with diseased leaves and soil in Eucalyptus plantations

The 482 Calonectria isolates used for molecular identification in the current study were identified as six species, which resided in three species complexes. The six species were C.pseudoreteaudii (411 isolates, 85.27%), C.acaciicola (42 isolates, 8.71%), C.hongkongensis (16 isolates, 3.32%), C.aconidialis (seven isolates, 1.45%), C.chinensis (five isolates, 1.04%), and C.auriculiformis (one isolate, 0.21%) (Fig. 4).

Figure 4.

The isolate number and percentage of each Calonectria species at the eight sampling sites. “sp. 1, 2, 3, 4, 5, 6” indicate the six Calonectria species A isolates and species obtained from all eight sites B-I isolates and species obtained from a particular site (sites A–H).

At each of the eight sampling sites, C.pseudoreteaudii was dominant in the samples collected from both the diseased trees and soil under these trees, particularly at sites A–G located on the mainland of China. Calonectriaacaciicola isolates were obtained from site H in Hainan Province, and this species was also frequently isolated from both diseased trees and soil. The other four Calonectria species, C.hongkongensis, C.aconidialis, C.chinensis, and C.auriculiformis, were only isolated from samples collected from soils (Table 1, Figs 4, 5).

Figure 5.

Histogram showing the proportions of each of the six Calonectria species reside in three species complexes isolated from diseased leaves and soil at the eight sampling sites. The histograms in green and orange indicated isolates obtained from diseased trees and soils, respectively A species obtained from all the eight sites B–I species obtained from a particular site (sites A–H).

When considering the species complexes associated with diseased leaves and soils, all Calonectria isolates obtained from diseased trees resided in the C.reteaudii species complex; and 14.14% of Calonectria isolates obtained from soils resided in the C.kyotensis species complex. All isolates residing in the C.kyotensis species complex were obtained from soils. For the isolates residing in the C.reteaudii species complex, 62.69% of the isolates come from diseased trees and 37.31% were from soil samples (Table 1, Fig. 5).

Discussion

In this study, a systematic and comprehensive investigation of Calonectria leaf blight occurring on Eucalyptus plantations in a wide geographic range in southern China was conducted. The results of this study clearly showed that the Calonectria species in the C.cylindrospora species complex was occasionally distributed in Eucalyptus plantations. Calonectria species in both the C.reteaudii species complex and C.kyotensis species complex were widely distributed. The distribution patterns of Calonectria species in the C.reteaudii species complex and C.kyotensis species complex were related to diseased leaves and soil habitats during leaf blight outbreak season in Eucalyptus plantations in southern China.

The results of this study showed that all isolates obtained from diseased trees resided in the C.reteaudii species complex, which indicated that they are the causal agents of Calonectria leaf blight at the sampled sites in China. Moreover, C.pseudoreteaudii was the dominant species of all the eight sampling sites in the three provinces. This was consistent with previous studies in which C.pseudoreteaudii was frequently obtained from diseased Eucalyptus trees in Guangdong, Guangxi, Fujian, and Hainan Provinces in southern China (Chen et al. 2013; Wang and Chen 2020; Wu and Chen 2021; Li et al. 2023a; Liang et al. 2023). Calonectriaacaciicola was only isolated from site H in Hainan Province in this and a previous study by Liang et al. (2023). Furthermore, inoculation results from previous studies indicated that both C.pseudoreteaudii and C.acaciicola were highly virulent to the tested Eucalyptus genotypes (Liang et al. 2023). C.pseudoreteaudii is one of the main causal agents of Calonectria leaf blight widely observed in southern China, and C.acaciicola is causal agent of the disease in Hainan Province in particular.

It is still unclear whether the species in the C.reteaudii complex are soil-borne or not. The results of the previous studies consistently indicated that species in the C.reteaudii complex can survive in the soils, at least for a certain time (Crous 2002; Liu et al. 2021). Both C.pseudoreteaudii and C.acaciicola were frequently isolated from soils under the diseased trees in this study. Results of the previous research confirmed that Calonectria species in the C.reteaudii species complex were frequently isolated from soils under diseased Eucalyptus trees in southern China (Wu and Chen 2021; Li et al. 2023b). A recent population study showed that the genetic diversity of the C.pseudoreteaudii isolates obtained from diseased leaves was higher than that of the C.pseudoreteaudii isolates obtained from the soil in one Eucalyptus plantation, and the C.pseudoreteaudii isolates in soil may spread from diseased leaves (Wu et al. 2023). The results of the current study highlight that C.pseudoreteaudii from the soils in Eucalyptus plantations also needs to be carefully monitored for disease management purposes. It is necessary to clarify whether Calonectria in the C.reteaudii species complex is soil-borne or not and further understand the sources and dispersal pathways of the pathogens from this complex.

Previous studies showed that the species in the C.kyotensis complex were widely isolated from soils, both in natural forests and commercial plantations (Liu et al. 2021, 2022; Wu and Chen 2021, 2023; Li et al. 2023b; Liu and Chen 2023), and a relatively small number of isolates were isolated from susceptible Eucalyptus leaves (Li et al. 2023a; Liang et al. 2023). The research in this study indicated that all isolates residing in the C.kyotensis species complex were obtained from soils but not from diseased trees. Moreover, the results of this study revealed that isolates in the C.kyotensis species complex may not be the pathogens causing leaf blight in Eucalyptus. Further research is needed to clarify their ecological niche since they were also frequently isolated from diseased leaves (Li et al. 2023b; Liang et al. 2023).

Conclusion

This study clarified the distribution patterns of Calonectria species complexes related to the Calonectria isolated sources of diseased trees and soils during the disease outbreak season. The results of this study clearly showed that all isolates obtained from diseased leaves resided in the C.reteaudii species complex, and species in the C.reteaudii species complex were widely distributed in diseased leaves and soils. All the isolates residing in the C.kyotensis species complex were obtained from soils. This indicated that species in the C.kyotensis species complex are soil inhabitants. These results highlight that Calonectria species in the C.reteaudii species complex, but not in the C.kyotensis species complex, are the causal agents of Calonectria leaf blight in southern China. More attention should be paid to the causal agents of Calonectria leaf blight, especially C.pseudoreteaudii, with a wide geographic distribution during the disease outbreak season, for disease management in the future.

Citation

Wu WX, Chen SF (2024) Distribution patterns of Calonectria (Ascomycota, Sordariomycetes, Hypocreales, Nectriaceae) species complexes related to diseased leaves and soil habitats during leaf blight outbreak season in Eucalyptus plantations in southern China. MycoKeys 110: 117–140. https://doi.org/10.3897/mycokeys.110.130733

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

No ethical statement was reported.

Funding

This study was initiated through the bilateral agreement between the Governments of South Africa and China and supported by The National Key R&D Program of China (China-South Africa Forestry Joint Research Centre Project; Project No. 2018YFE0120900), the National Ten-thousand Talents Program (Project No. W03070115), and the Guangdong Top Young Talents Program in China (Project No. 20171172).

Author contributions

Conceptualization: SFC. Formal analysis: WXW. Funding acquisition: SFC. Methodology: SFC, WXW. Project administration: SFC. Resources: SFC, WXW. Software: WXW. Supervision: SFC. Writing - original draft: WXW. Writing - review and editing: SFC, WXW.

Author ORCIDs

WenXia Wu https://orcid.org/0009-0000-1685-9627

ShuaiFei Chen https://orcid.org/0000-0002-3920-9982

Data availability

All of the data that support the findings of this study are available in the main text or Supplementary Information.

Supplementary materials

Supplementary material 1

Calonectria isolates obtained from eight Eucalyptus plantations in this study

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

WenXia Wu, ShuaiFei Chen

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Supplementary material 2

Phylogenetic tree of Calonectria species based on maximum likelihood (ML) analyses of a combined DNA dataset of tef1 gene sequences

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

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Supplementary material 3

Phylogenetic tree of Calonectria species based on maximum likelihood (ML) analyses of a combined DNA dataset of tub2 gene sequences

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

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Supplementary material 4

Phylogenetic tree of Calonectria species based on maximum likelihood (ML) analyses of a combined DNA dataset of cmdA gene sequences

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

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Supplementary material 5

Phylogenetic tree of Calonectria species based on maximum likelihood (ML) analyses of a combined DNA dataset of his3 gene sequences

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.

WenXia Wu, ShuaiFei Chen

Data type

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