Abstract
Alternaria species are commonly found as saprophytes, endophytes and plant pathogens. During a survey of small-spored Alternaria in China, two new species were discovered from Cucurbitaceae plants collected in Hubei and Sichuan provinces. This study identified two new species of Alternaria using seven genes (ITS, GAPDH, TEF1, RPB2, Alt a 1, EndoPG, and OPA10-2) for phylogenetic analyses and morphological characteristics. The two new species A.jingzhouensis and A.momordicae were described and illustrated. Alternariajingzhouensissp. nov., associated with Citrulluslanatus, is characterized by producing muriform, ellipsoidal, flask-shaped, rostrate, and beaked conidia. It differs from A.koreana, A.ovoidea, and A.baoshanensis by bearing conidia in a simple conidiogenous locus with occasionally longer beaks in a chain, and from A.momordicaesp. nov. by having shorter beaks. Alternariamomordicaesp. nov. from Momordicacharantia was distinct from A.koreana, A.ovoidea, and A.baoshanensis by producing muriform, long ellipsoid or ovoid to obclavate, sometimes inverted club-shaped conidia on a single conidiogenous locus with a wider body and longer beak in a chain, and distinct from A.jingzhouensissp. nov. by a longer beak conidia. These two species were clearly distinguished from other species in the section Alternaria based on DNA based phylogeny and morphological characteristics. The morphological features were discussed and compared to relevant species in the present paper.
Key words: Morphology, novel species, phylogeny, small-spored Alternaria, taxonomy
Introduction
The Cucurbitaceae, also called cucurbits or the gourd family, consists of approximately 975 species belonging to 98 genera (Xu and Chang 2017). There are 35 genera with 151 species in China (Raven and Wu 2022). This family includes highly nutritious vegetables with significant economic value, such as cucumber, pumpkin, and so on. Watermelon (Citrulluslanatus (Thunb.) Matsum. & Nakai) is a popular fruit worldwide, and its seeds contain high levels of proteins, lipids and medicinal properties (Wani et al. 2011, Maoto et al. 2019). China is the world’s leading producer of watermelons (Qiang et al. 2024). Bitter gourd (Momordicacharantia L.) is normally cultivated in China for its fruit as a popular vegetable and traditional medicine (Sun et al. 2023). Alternaria-like leaf blight can severely affect the crop production of Cucurbitaceae (Maheswari and Sankaralingam 2010; Ma et al. 2021). Many Alternaria species have been reported to be associated with cucurbit plants, including A.alternata (Fr.) Keissl. (Chen et al. 1993; Zhao et al. 2016a, 2016b; Ma et al. 2021), A.baoshanensis J.F. Li, Phookamsak & Jeewon (Li et al. 2023), A.brassicae (Berk.) Sacc. (Simmons 2007), A.brassicaevar.nigrescens (Peglion) Sacc. & Traverso (Simmons 2007), A.caudata Cooke & Ellis (Simmons 2007), A.cucumericola E.G. Simmons & C.F. Hill (Simmons 2007), A.cucumerina (Ellis & Everh.) J.A. Elliott (Chen et al. 1993; Zhang 2003; Simmons 2007; Ma et al. 2021), A.cylindrorostra T.Y. Zhang (Zhang 2003; Simmons 2007), A.gaisen Nagano ex Bokura (Ma et al. 2021), A.granulosa (Bubák) E.G. Simmons (Simmons 2007), A.hydrangeae D. F. Pei & J. X. Deng (Liu et al. 2022), A.infecotria E.G. Simmons (Ma et al. 2021), A.loofahae E.G. Simmons & Aragaki (Simmons 2007), A.nigrescens (Peglion) Neerg. (Simmons 2007), A.peponicola (Rabenh.) E.G. Simmons (Zhang 2003; Simmons 2007), A.peponis Yatel (Simmons 2007), and A.tenuissima (Kunze) Wiltshire (Chen et al. 1993; Zhao et al. 2016a, 2016b; Ma et al. 2021).
The genus AlternariaNees von Esenbeck (1816) is categorized according to its morphological characteristics, typified by A.alternata with muriform and catenulate conidia (Simmons 2007). Simmons (1992) applied standard criteria to achieve solid taxonomic outcomes for Alternaria species, primarily relying on the sporulation patterns and developmental morphology of conidia. In 2007, Simmons illustrated approximately 276 species (148 large-spored species and 128 small-spored species) and provided a final summary of morphological taxonomy on Alternaria. The small-spored species fall into 10 subsections containing the type species of A.alternata (Simmons 2007). In 2003, Zhang identified approximately 80 small-spored species associated with specific host plant families in China.
To date, the utilization of multigene phylogenetic analyses has played a crucial role in understanding the Alternaria genus (Pryor and Gilbertson 2000; Pryor and Bigelow 2003; Hong et al. 2005; Runa et al. 2009; Woudenberg et al. 2013, 2014; Lawrence et al. 2013, 2014, 2016; Poursafar et al. 2018). The genus contains 24 internal clades (sections) and six monotypic lineages (Woudenberg et al. 2013) using type or referenced strains collected by Simmons (2007), which has recently been updated to 29 sections (Li et al. 2023). Small-spored Alternaria species are also frequently isolated from Cucurbitaceae in China (Ma et al. 2021). Woudenberg et al. (2015) provided a clear and stable species classification of section Alternaria based on the genomic and multi-loci analyses, from which the species commonly produce concatenated conidia (Norphanphoun et al. 2021; Li et al. 2022; Gou et al. 2022). Consequently, the combination of morphology and molecular techniques provides a better understanding of species in section Alternaria (Aung et al. 2020).
During the investigation of small-spored Alternaria species in China, two new taxa were isolated from gourd plants of Citrulluslanatus and Momordicacharantia. The aim of this study was to characterize and differentiate both taxa using morphology and multigene sequence analyses. This research sought to enhance understanding of Alternaria species diversity within the Cucurbitaceae family, offering crucial taxonomic information for species conservation efforts.
Materials and methods
Isolation
Leaves of Citrulluslanatus and Momordicacharantia with necrotic spots were collected from Jingzhou, Hubei in 2022 and Deyang City, Sichuan Province in 2016 China, respectively. To facilitate isolation, the specimens were carefully enclosed in sterile plastic bags and transported to the laboratory. Subsequently, the tissues were accurately divided into small segments, arranged on moist filter papers within Petri dishes, and incubated at 25 °C to promote spore production. After sporulation, spores of Alternaria were individually collected using sterilized glass needles under a stereo microscope (Shunyu SZM series) and transferred onto potato dextrose agar (PDA) plates. Each distinct culture was purified and preserved in test-tube slants maintained at 4 °C. Additionally, dried cultures derived from individual spores and reference strains were stored in the Fungi Herbarium of Yangtze University (YZU), located in Jingzhou, Hubei, China.
Morphology
To study the features of colonies, the strains were grown on PDA at 25 °C for 7 days without light. To examine the characteristics of the conidia (size, shape, sporulation, etc.), fresh mycelia were transferred to potato carrot agar (PCA) and V8 juice agar (V8A) plates and then placed in an incubator at 22 °C with an 8-hour light cycle for 7 days (Simmons 2007). A total of 50 conidia were randomly selected and photographed for the morphological determination after mounting the conidia into lactophenol picric acid under an ECLIPSE Ni-U microscope system (Nikon, Japan). The sporulation patterns and morphological characteristics were also recorded.
DNA extraction, PCR amplification and sequencing
Fresh mycelia growing on PDA were used to extract genomic DNA with the CTAB method, as described by Watanabe et al. (2010). To amplify multigene fragments, including the internal transcribed spacer rDNA region (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), translation elongation factor 1 alpha (TEF1), RNA polymerase second largest subunit (RPB2), Alternaria major allergen gene (Alt a 1), endopolygalacturonase gene (EndoPG), and an anonymous gene region (OPA10-2), primer pairs were employed including ITS5/ITS4 (White et al. 1990), gpd1/gpd2 (Berbee et al. 1999), EF1-728F/EF1-986R (Carbone and Kohn 1999), RPB2-5F/RPB2-7cR (Liu et al. 1999), Alt-for/Alt-rev (Hong et al. 2005), PG3/PG2b (Andrew et al. 2009) and OPA10-2L/OPA10-2R (Andrew et al. 2009), respectively. The PCR reaction mixture was 25 μL, including 21 μL of 1.1×Taq PCR Star Mix from TSINGKE, 2 μL of template DNA, and 1 μL of each primer. The amplification process was carried out in an Eppendorf Mastercycler, following the protocols outlined by Woudenberg et al. (2015). After a successful amplification, the PCR products were purified and sequenced by TSINGKE company (Beijing, China). The obtained sequences were assembled using BioEdit v. 7.2.3 (Hall 1999) and primarily aligned with PHYDIT v.3.2 (Chun 1995) then deposited into GenBank (https://www.ncbi.nlm.nih.gov/) (Table 1).
Table 1.
Alternaria strains used in this study and their GenBank accession numbers.
| Species | Strain | Host/Substrate | Country | GenBank accession numbers | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| ITS | GAPDH | TEF1 | RPB2 | Alt a 1 | EndoPG | OPA10-2 | ||||
| A.alternantherae | CBS 124392 | Solanummelongena | China | KC584179 | KC584096 | KC584633 | KC584374 | KP123846 | np | np |
| A.alternata | CBS 916.96T | Arachishypogaea | India | AF347031 | AY278808 | KC584634 | KC584375 | AY563301 | JQ811978 | KP124632 |
| CBS 106.34T | Linumusitatissimum | Unknown | Y17071 | JQ646308 | KP125078 | KP124771 | KP123853 | KP124000 | KP124608 | |
| CBS 102596T | Citrusjambhiri | USA | KP124328 | KP124183 | KP125104 | KP124796 | KP123877 | KP124030 | KP124637 | |
| CBS 121336T | Allium sp. | USA | KJ862254 | KJ862255 | KP125141 | KP124833 | KJ862259 | KP124067 | KP124676 | |
| CBS 121547T | Pyrusbretschneideri | China | KP124372 | KP124224 | KP125150 | KP124842 | KP123920 | KP124076 | KP124685 | |
| CBS 119543T | Citrusparadisi | USA | KP124363 | KP124215 | KP125139 | KP124831 | KP123911 | KP124065 | KP124674 | |
| CBS 918.96R | Dianthuschinensis | UK | AF347032 | AY278809 | KC584693 | KC584435 | AY563302 | KP124026 | KP124633 | |
| CBS 127671T | Stanleyapinnata | USA | KP124381 | KP124233 | KP125159 | KP124851 | KP123929 | KP124085 | KP124694 | |
| CBS 121455T | Broussonetiapapyrifera | China | KP124368 | KP124220 | KP125146 | KP124838 | KP123916 | KP124072 | KP124681 | |
| CBS 117.44T | Godetia sp. | Denmark | KP124303 | KP124160 | KP125079 | KP124772 | KP123854 | KP124001 | KP124609 | |
| CBS 127672T | Astragalusbisulcatus | USA | KP124382 | KP124234 | KP125160 | KP124852 | KP123930 | KP124086 | KP124695 | |
| CBS 102.47R | Citrussinensis | USA | KP124304 | KP124161 | KP125080 | KP124773 | KP123855 | KP124002 | KP124610 | |
| CBS 102599T | Minneolatangelo | Turkey | KP124330 | KP124185 | KP125106 | KP124798 | KP123879 | KP124032 | KP124639 | |
| CBS 102595T | Citrusjambhiri | USA | FJ266476 | AY562411 | KC584666 | KC584408 | AY563306 | KP124029 | KP124636 | |
| CBS 103.33T | Soil | Egypt | KP124302 | KP124159 | KP125077 | KP124770 | KP123852 | KP123999 | KP124607 | |
| A.arborescens | CBS 126.60 | Wook | UK | KP124397 | KP124249 | KP125175 | KP124867 | JQ646390 | KP124101 | KP124710 |
| CBS 119545T | Senecioskirrhodon | New Zealand | KP124409 | KP124260 | KP125187 | KP124879 | KP123956 | KP124113 | KP124723 | |
| CBS 101.13T | Peat soil | Switzerland | KP124392 | KP124244 | KP125170 | KP124862 | KP123940 | KP124096 | KP124705 | |
| CBS 105.24 | Solanumtuberosum | Unknown | KP124393 | KP124245 | KP125171 | KP124863 | KP123941 | KP124097 | KP124706 | |
| CBS 119544T | Avenasativa | New Zealand | KP124408 | JQ646321 | KP125186 | KP124878 | KP123955 | KP124112 | KP124722 | |
| CBS 105.49 | Contaminant blood culture | Italy | KP124396 | KP124248 | KP125174 | KP124866 | KP123944 | KP124100 | KP124709 | |
| CBS 112749 | Malusdomestica | South Africa | KP124401 | KP124253 | KP125179 | KP124871 | KP123948 | KP124105 | KP124715 | |
| A.baoshanensis | MFLU 21-0124T | Curcubitamoschata | China | MZ622003 | OK236706 | OK236613 | OK236659 | OK236760 | np | np |
| MFLU 21-0296 | C.moschata | China | MZ622004 | OK236707 | OK236612 | OK236660 | OK236759 | np | np | |
| A.breviconidiophora | MFLUCC 21-0786T | Digitalis sp. | Italy | MZ621997 | OK236698 | OK236604 | OK236651 | OK236751 | np | np |
| A.burnsii | CBS 118817T | Tinosporacordifolia | India | KP124424 | KP124274 | KP125202 | KP124893 | KP123971 | KP124128 | KP124738 |
| CBS 118816T | Rhizophoramucronata | India | KP124423 | KP124273 | KP125201 | KP124892 | KP123970 | KP124127 | KP124737 | |
| A.ellipsoidialis | MFLUCC 21-0132T | Brassica sp. | Italy | MZ621989 | OK236690 | OK236596 | OK236643 | OK236743 | np | np |
| A.eupatoriicola | MFLUCC 21-0122T | Eupatoriumcannabinum | Italy | MZ621982 | OK236683 | OK236589 | OK236636 | OK236736 | np | np |
| A.falcata | MFLUCC 21-0123T | Atriplex sp. | Italy | MZ621992 | OK236693 | OK236599 | OK236649 | OK236746 | np | np |
| A.gaisen | CBS 632.93R | Pyruspyrifolia | Japan | KC584197 | KC584116 | KC584658 | KC584399 | KP123974 | AY295033 | KP124742 |
| CBS 118488R | P.pyrifolia | Japan | KP124427 | KP124278 | KP125206 | KP124897 | KP123975 | KP124132 | KP124743 | |
| A.gossypina | CBS 102601T | Minneolatangelo | Colombia | KP124433 | KP124282 | KP125212 | KP124903 | KP123979 | KP124138 | KP124749 |
| CBS 104.32T | Gossypium sp. | Zimbabwe | KP124430 | JQ646312 | KP125209 | KP124900 | JQ646395 | KP124135 | KP124746 | |
| A.jacinthicola | CBS 878.95 | Arachishypogaea | Mauritius | KP124437 | KP124286 | KP125216 | KP124907 | KP123983 | KP124142 | KP124753 |
| CBS 133751T | Eichhorniacrassipes | Mali | KP124438 | KP124287 | KP125217 | KP124908 | KP123984 | KP124143 | KP124754 | |
| A.jingzhouensis sp. nov. | YZU 221144T | Citrulluslanatus | China | OR883772 | OR887690 | OR887686 | OR887688 | OR887694 | OR887692 | OR887684 |
| YZU 221145 | C.lanatus | China | OR901948 | OR914170 | OR914166 | OR914168 | OR914174 | OR914172 | OR914176 | |
| A.koreana | SPL2-1T | Atractylodesovata | Korea | LC621613 | LC621647 | LC621715 | LC621681 | LC631831 | LC631844 | LC631857 |
| SPL2-4 | A.ovata | Korea | LC621615 | LC621649 | LC621717 | LC621683 | LC631832 | LC631845 | LC631858 | |
| A.longipes | CBS 121333R | Nicotianatabacum | USA | KP124444 | KP124293 | KP125223 | KP124914 | KP123990 | KP124150 | KP124761 |
| CBS 540.94R | N.tabacum | USA | AY278835 | AY278811 | KC584667 | KC584409 | AY563304 | KP124147 | KP124758 | |
| A.minimispora | MFLUCC 21-0127T | Citrulluslanatus | Thailand | MZ621980 | OK236705 | OK236587 | OK236634 | OK236734 | np | np |
| A.momordicae sp. nov. | YZU 161378T | Momordicacharantia | China | OR883774 | OR887691 | OR887687 | OR887689 | OR887695 | OR887693 | OR887685 |
| YZU 161379 | M.charantia | China | OR901949 | OR914171 | OR914167 | OR914169 | OR914175 | OR914173 | OR914177 | |
| A.muriformispora | MFLUCC 21-0784T | Plantago sp. | Italy | MZ621976 | OK236677 | OK236583 | OK236630 | OK236730 | np | np |
| A.obpyriconidia | MFLUCC 21-0121T | Viciafaba | Italy | MZ621978 | OK236680 | OK236585 | OK236633 | OK236732 | np | np |
| A.ovoidea | MFLUCC 0782T | Dactylisglomerata | Italy | MZ622005 | OK236708 | OK236614 | OK236661 | OK236761 | np | np |
| MFLU 21- 0298 | D.glomerata | Italy | MZ622006 | OK236709 | OK236615 | OK236662 | OK236762 | np | np | |
| A.orobanches | MFLUCC 21-0137T | Orobanche sp. | Italy | MZ622007 | OK236710 | np | np | OK236763 | np | np |
| MFLU 21-0303 | Orobanche sp. | Italy | MZ622008 | OK236711 | np | np | OK236764 | np | np | |
| A.phragmiticola | MFLUCC 21-0125T | Phragmites sp. | Italy | MZ621994 | OK236696 | OK236602 | OK236649 | OK236749 | np | np |
| A.rostroconidia | MFLUCC 21-0136T | Arabis sp. | Italy | MZ621969 | OK236670 | OK236576 | OK236623 | OK236723 | np | np |
| A.salicicola | MFLUCC 22-0072T | Salixalba | Russia | MZ621999 | OK236700 | OK236606 | OK236653 | OK236753 | np | np |
| A.tomato | CBS 103.30 | Solanumlycopersicum | Unknown | KP124445 | KP124294 | KP125224 | KP124915 | KP123991 | KP124151 | KP124762 |
| CBS 114.35 | S.lycopersicum | Unknown | KP124446 | KP124295 | KP125225 | KP124916 | KP123992 | KP124152 | KP124763 | |
| A.torilis | MFLUCC 14-0433T | Torilisarvensis | Italy | MZ621988 | OK236688 | OK236594 | OK236641 | OK236741 | np | np |
Notes: Novel species proposed in this study are marked in bold. Ex-type strains are marked ‘T’. Representative strains are marked ‘R’. No products are ‘np’.
Phylogenetic analyses
Preliminary BLAST searches on the National Center for Biotechnology Information (NCBI) website (https://blast.ncbi.nlm.nih.gov/Blast.cgi) indicated that the current species are highly similar to species within the Alternaria genus. Subsequently, sequence data of 57 Alternaria strains and A.alternantherae Holcomb & Antonop. CBS 124392 (outgroup) were retrieved from the GenBank database and referenced from relevant publications (Woudenberg et al. 2015; Li et al. 2022; Romain et al. 2022) (Table 1). The gene sequences were concatenated and edited manually with equal weight in MEGA v.11.0.13 (Tamura et al. 2021), and gaps were treated as missing data. Bayesian inference (BI) analysis was carried out using MrBayes v. 3.2.6 (Ronquist et al. 2012). This analysis employed a Markov Chain Monte Carlo (MCMC) algorithm to estimate Bayesian posterior probabilities. The best-fit evolutionary model (GTR+I+G) was determined using MrModeltest v. 2.3 (Nylander 2004, Posada and Crandall 1998) with the Akaike Information Criterion (AIC). In MrModeltest, the file "MrModelblock″ was executed in the PAUP path (Swofford 2002) and the MrMt path (Nylander 2004). Bayesian analyses included two parallel runs for 10,000,000 generations (ngen) with the stop rule option and a sampling frequency set to every 100 generations (samplefreq=100). The run was stopped when the standard deviation of split frequencies reached a value below 0.01. The first 25% of sampled trees were discarded as burn-in. Additionally, a maximum likelihood (ML) analysis was performed using RAxML v.7.0.3 (Stamatakis et al. 2008). The GTRGAMMAI model was implemented using ML+ rapid bootstrap setting with 1000 replications to assess branch support. The tree was visualized with FigTree v1.4.3 (Rambaut 2016). Nodes in the phylogram displayed branch support values equal to or above 0.60/60% for posterior probability (PP)/bootstrap (BS) values.
Results
Phylogenetic analyses
The dataset includes a total of 58 Alternaria strains with 3627 characters in total after alignment. The dataset consists of 533 characters for ITS, 574 for GAPDH, 216 for TEF1, 757 for RPB2, 444 for EndoPG, 469 for Alt a 1, and 634 for OPA10-2. Both Bayesian inference (BI) and maximum likelihood (ML) analyses yielded similar topologies. The ML tree was selected for discussing the placement of our new species (Fig. 1). The results indicated that all Alternaria strains in the present study fell into Alternaria section with PP values of 1.0. The present four strains separated into two individual clades sister to A.koreana O. Hassan, B.B.N.D. Romain, J.S. Kim & T. Chang, A.ovoidea J.F. Li, Camporesi, Bhat & Phookamsak, A.baoshanensis, and A.orobanches J.F. Li, Camporesi, Phookamsak & Jeewon (Bayesian posterior probability (BI-BPP)/Maximum-Likelihood bootstrap proportions (ML-BS) = 0.64/74%).
Figure 1.
Phylogenetic tree of the Alternaria species most related to the new taxa based on maximum likelihood analysis using the combined gene sequences of ITS, GAPDH, TEF1, RPB2, Alt a 1, EndoPG and OPA10-2 which rooted with Alternariaalternantherae (CBS 124392) from sect. Alternantherae. The Bayesian posterior probabilities >0.60 (PP) and bootstrap support values >60 (BS) are given at the nodes (PP/BS). The novel species are highlighted in bold. Ex-type isolates are marked with a superscript T and Representative isolates are marked with a superscript R.
The clade containing YZU 161378 and YZU 161379 was closely related to A.baoshanensis, A.koreana, A.ovoidea, and forming a distinct branch. While another clade, YZU 221144 and YZU 221145 was found to be independent with a posterior probability (PP) of 1.00 and bootstrap (BS) values of 68%, and it was closely related to A.orobanches. These results suggest that the present strains represent two new taxa.
Taxonomy
. Alternaria jingzhouensis
S.L.L. Aung & J.X. Deng sp. nov.
D4E3DDD8-26E9-5A6C-969E-6CC03CAF933F
MycoBank No: 851272
Figure 2.
Alternariajingzhouensis sp. nov. (ex-type YZU 221144) A, B seven-day-old culture on PDAC, D conidiophores and conidia on PCA and V8A, respectively E, F conidia on PCA and V8A, respectively. Scale bars: 25 μm (E, F); 50 μm (C, D).
Type.
China, Hubei Province, Jingzhou city, Yangtze University (west campus) on infected leaves of Citrulluslanatus 2022, F.Y Liu, (YZU-H-2022030, holotype), ex-type culture YZU 221144.
Etymology.
Named after the collecting locality, Jingzhou (Hubei, China)
Description.
Colonies on PDA (7 d at 25 °C) pale luteous to amber in the center, white at the edges, light to moderate rosy buff or pale saffron in reverse, cottony surface and 49–52 mm in diam., at 25 °C for 7 days (Fig. 2A, B). On PCA (7 d at 22 °C), conidiophores arising from substrate, simple, straight or flexuous, light to olivaceous buff, 41–99 (–151) × 3.5–5 μm (x̄ = 73 × 4.4 µm, n = 20), conidiogenous cells 5–11 × 3–6 µm (x̄ = 8 × 4 µm, n = 20), mono- to polytretic, terminal, determinate, cylindrical, olivaceous buff, smooth, thin-walled, apically doliiform, with 1 conidiogenous locus cicatrized on conidial secession, sometimes swollen near conidiogenous loci; conidia 3–5 units per chain, arising from the apex or near the apex of the conidiophores or terminal hyphae, muriform, ellipsoidal, flask-shaped, rostrate, beaked, 28–51 × 11–21 μm (x̄ = 38 × 16.4, n = 50), with 1–4 transverse septa with 0–2 branching (Fig. 2C, E); On V8A (7 d at 22 °C), conidiophores 40–94 × 4–7 μm (x̄ = 58 × 5, n = 20), simple, straight or flexuous, light to olivaceous buff; conidiogenous cells 5–13 × 3–6 µm (x̄ = 8 × 4 µm, n = 20), mono- to polytretic, terminal, determinate, cylindrical, olivaceous buff, smooth, thin-walled, apically doliiform, with 1 conidiogenous locus, sometimes swollen near conidiogenous loci cicatrized on conidial secession; conidia 3–5 units per chain, arising from the apex or near the apex of the conidiophores or terminal hyphae, muriform, ellipsoidal, flask-shaped, rostrate, beaked, 22–51 × 3–16 μm (x̄ = 33.9×13.2, n = 50), 1–6 transverse septa with 0–2 branching (Fig. 2D, F).
Additional isolate examined.
China, Hubei Province, Jingzhou city, Yangtze University (west campus) on infected leaves of Citrulluslanatus 2022, F.Y Liu, living culture YZU 221145.
Notes.
Phylogenetically, A.jingzhouensis sp. nov. is different from its sister species A.baoshanensis, A.koreana, A.momordicae sp. nov., A.orobanches and A.ovoidea based on sequences derived from seven genes (Fig. 1). After conducting a nucleotide pairwise comparison as recommended by Jeewon and Hyde (2016), the present species can be readily distinguished from the closet species A.koreana, A.momordicae sp. nov. and A.orobanches constructed on any of the ITS, GAPDH, TEF1, RPB2, Alt a 1, EndoPG, and OPA10-2 genes, which has 1 bp difference in the ITS region, 1 bp in GAPDH, 1 bp in TEF1, 7 pb in RPB2, 9 bp in Alt a1, 10 bp in EndoPG, and 4 bp in OPA10-2 when compared with A.koreana, 1 bp in GAPDH, 4 bp in RPB2, and 11 bp in OPA10-2 when compared with A.momordicae sp. nov. and 49 bp differences in the ITS region when compared with sister species A.orobanches. Morphologically, the species is distinct from A.baoshanensis, A.koreana, and A.ovoidea as it produces conidia on a simple conidiogenous locus with occasionally longer beaks in a chain of 3–5 units, and from A.momordicae sp. nov. by having shorter beaks (Table 2).
Table 2.
Conidial features of the novel Alternaria species proposed here and their closest relatives in section Alternaria.
| Species | Conidia | Conidia per chain | Medium | Reference | |||
|---|---|---|---|---|---|---|---|
| Shape | Body (µm) | Beak (µm) | Septa | ||||
| A.baoshanensis | Subglobose to ellipsoidal, or subcylindrical to obpyriform | 25–60 × 12–22 | Short beak | 3–6 | 1–3 | PCA | Li et al. (2023) |
| A.jingzhouensis sp. nov. | Ellipsoidal, flask-shaped, rostrate, beaked | 28–51 × 11–21 | 2–7(–15) | 1–4 | 3–5 | PCA | Present study |
| 22–51 × 3–16 | 3–7 | 1–6 | 3–5 | V8A | Present study | ||
| A.koreana | Obovate to long ellipsoid | 12.9–61.2×8.6–20.7 | 4.5–9.1 | 2–8 | 1–2 | SNA | Romain et al. (2022) |
| A.momordicae sp. nov. | Obclavate, inverted club-shaped | 6–42 × 4–34 | 2–19.5 | 1–5 | 3–4 | PCA | Present study |
| 24–61 × 10–17 | 3–25.5 | 1–5 | 3–4 | V8A | Present study | ||
| A.orobanches | Obclavate to ovoid | 20–50 × 10–20 | – | 3–6 | 1–2 | PCA | Li et al. (2023) |
| A.ovoidea | Ovoid | 48–65 × 15.5–30 | – | 1–3 | 1 | PDA | Li et al. (2022) |
. Alternaria momordicae
S.L.L. Aung & J.X. Deng sp. nov.
40F7E142-199A-5257-84B7-0C9E5518C20F
MycoBank No: 851270
Figure 3.
Alternariamomordicae sp. nov. (ex-type YZU 161378) A, B seven-day-old culture on PDAC, D conidiophores and conidia on PCA and V8A, respectively E, F conidia on PCA and V8A, respectively. Scale bars: 25 μm (E, F); 50 μm (C, D).
Type.
China, Sichuan Province, Deyang city infected leaves of Momordicacharantia. 2016, J.X Deng, (YZU-H-2016001, holotype), ex-type culture YZU 161378.
Etymology.
Refers to the host genus, Momordica.
Description.
Colonies on PDA (7 d at 25 °C) greyish yellow-green, light white at the edge, buff to salmon in reverse, surface compact, 50–55 mm in diam. (Fig. 3A, B). On PCA (7 d at 22 °C), conidiophores arising from substrate, simple, straight or flexuous, septate, olivaceous buff to olivaceous, 26.5–93 × 3–4 μm (x̄ = 59.5× 3.8 μm, n = 20); conidiogenous cells 5–10 × 3–5 µm (x̄ = 7 × 4 µm, n = 20), mono- to polytretic, terminal, determinate, cylindrical, olivaceous buff to olivaceous, smooth, thin-walled, apically doliiform, with 1 conidiogenous locus cicatrized on conidial secession, sometimes swollen near conidiogenous loci; conidia 3–4 units per chain, arising from the apex or near the apex of the conidiophores or terminal hyphae, muriform, long ellipsoid or ovoid to obclavate, sometime inverted club-shaped, 6–42 × 4–34 μm (x̄ = 32.8 × 13.5 μm, n = 50), 1–5 transverse septa, apical beak 2–19.5 μm long and 1–2 septa (Fig. 3C, E); On V8A(7 d at 22 °C), conidiophores straight or curved, smooth-walled, olivaceous buff 23–63(–208) × 3–5 μm (x̄ = 64.9 × 4.2 μm, n = 20); conidiogenous cells 5–13 × 3–4 µm (x̄ = 7 × 4 µm, n = 20), mono- to polytretic, terminal, determinate, cylindrical, olivaceous buff, smooth, thin-walled, apically doliiform, with 1 conidiogenous locus cicatrized on conidial secession, sometimes swollen near conidiogenous loci; conidia 3–4 units per chain, muriform, long ellipsoid or ovoid to obclavate, inverted club-shaped, 24–61×10–17 μm (x̄ = 39 × 14.3 μm, n = 50), 1–5 transverse septa with apical beak 3–25.5 μm long and 1–2 septa (Fig. 3D, F).
Additional isolate examined.
China, Sichuan Province, Deyang city infected leaves of Momordicacharantia. 2016, J.X Deng, living culture YZU 161379.
Notes.
After the combined dataset of ITS, GAPDH, TEF1, RPB2, Alt a 1, EndoPG and OPA10-2 gene fragments, A.momordicae sp. nov. is readily distinguished from its sister species A.baoshanensis, A.jingzhouensis sp. nov., A.koreana, and A.ovoidea, (Fig. 1). After a nucleotide pairwise comparison as suggested by Jeewon and Hyde (2016), the present species can be readily distinguished from the closet species A.koreana and others related a novel species based on any of the ITS, GAPDH, TEF1, RPB2, Alt a 1, EndoPG, and OPA10-2 genes, which has 1 bp difference in the ITS region, 1 bp in GAPDH, 1 bp in TEF1, 4 bp in RPB2, 8 bp in Alt a1 and 10 bp in EndoPG when compared with A.koreana and 1 bp in GAPDH, 4 bp in RPB2, and 11 bp in OPA10-2 when compared with A.jingzhouensis sp. nov.. Morphologically, A.momordicae sp. nov. produces conidia on PCA that are significantly shorter than those on V8A. It can be distinguished from A.baoshanensis, A.koreana, and A.ovoidea by producing conidia on a single conidiogenous locus with a wider body and longer beak in a chain of 3–4 units. Additionally, it differs from A.jingzhouensis sp. nov. by having a longer beak (Table 2).
Discussion
Most of the Alternaria species published before the year 2000s relied on morphology to characterize the species status (Simmons 2007). In this study, two new Alternaria species, A.jingzhouensis and A.momordicae, have been identified and illustrated using the morphological method of Simmons (2007) and phylogenetic analysis of seven gene loci. Both resemble the type small-spored species of A.alternata in morphology but are easily distinguished by short chains, which also differentiate them from each other and their phylogenetically closely related species of A.baoshanensis, A.koreana, A.ovoidea and A.orobanches by the chain formation of sporulation patterns (Table 2). In recent publications, the Alternaria species descriptions have not followed the morphological standard created by Simmons (2007) (Romain et al. 2022; Li et al. 2022). Simmons (2007) classified the genus Alternaria into small-spored and large-spored taxa based on morphology. Andrew et al. (2009) noted that phylogenetic studies have confirmed a distinct separation between large- and small-spored Alternaria species. Woudenberg et al. (2015) identified 35 morphospecies as synonyms of A.alternata, but their relationships remain unclear due to inconsistencies and lack of detailed morphological information. Accurate identification and classification of species within these small-spored Alternaria species require strong identification through multigene sequence analysis (Kgatle et al. 2018). Li et al. (2023) described that recent studies using combined multi-locus phylogeny suggest that certain A.alternata species classified under section Alternaria may not constitute a monophyletic group in DNA sequence-based phylogenies. To reduce potential misidentification of morphological characteristics within this section, this study utilized PCA and V8A media for 7 days at 22 °C to identify Alternaria species, following Simmons’ (2007) recommendations. These media effectively promote typical morphological characteristics. Hence, it is strongly recommended to use the standard of morphological identification for further describing small-spored and large-spored Alternaria in order to reduce taxonomic ambiguity caused by different temperatures and substrates.
With the development of molecular studies, the species-group was re-defined and the section Alternaria was introduced and updated (Pryor and Gilbertson 2000; Lawrence et al. 2013; Woudenberg et al. 2013; Li et al. 2023). The section Alternaria is one of the small-spored Alternaria species groups and comprises 11 phylogenetic species and one species complex (Woudenberg et al. 2015). The two new Alternaria species are identified as members of section Alternaria according to the multigene sequence analysis of ITS, GADPH, RPB2, TEF1, Alt a 1, EndoPG and OPA10-2 gene sequences, which are close to A.baoshanensis (Li et al. 2023) from Curcubitamoschata (Cucurbitaceae), A.koreana (Romain et al. 2022) from Atractylodesovata (Compositae), A.orobanches (Li et al. 2023) from Orobanche sp. (Orobanchaceae), and A.ovoidea (Li et al. 2022) from Dactylisglomerata (Poaceae). Three genes, GAPDH, RPB2, and OPA10-2, provide more informative data for the classification of the current species.
Small-spored Alternaria species have been frequently reported on Cucurbitaceae plants worldwide, including A.alternata (Chen et al. 1993; Zhao et al. 2016a, 2016b; Ma et al. 2021), A.baoshanensis (Li et al. 2023), A.caudata (Simmons 2007), A.gaisen (Ma et al. 2021), A.infecotria (Ma et al. 2021), A.peponicola (Zhang 2003; Simmons 2007), and A.tenuissima (Chen et al. 1993; Zhao et al. 2016a, 2016b; Ma et al. 2021). The present two small-spored species, A.jingzhouensis sp. nov. and A.momordicae sp. nov., were first found on C.lanatus and M.charantia, respectively, in China. Pathogenicity tests were performed on detached and living leaves for the two new species, which showed weak pathogenicity (data not shown). However, they did exhibit a certain level of aggressiveness on cucurbit plants. The two species, A.jingzhouensis sp. nov. and A.momordicae sp. nov., were found to be non-pathogenic to their host plants, possibly due to their saprophytic or weakly pathogenic nature when encountering resistance from C.lanatus and M.charantia. These findings provide valuable insights into Alternaria leaf diseases in Cucurbitaceae.
Supplementary Material
Citation
Aung SLL, Liu F-Y, Gou Y-N, Nwe ZM, Yu Z-H, Deng J-X (2024) Morphological and phylogenetic analyses reveal two new Alternaria species (Pleosporales, Pleosporaceae) in Alternaria section from Cucurbitaceae plants in China. MycoKeys 107: 125–139. https://doi.org/10.3897/mycokeys.107.124814
Additional information
Conflict of interest
The authors have declared that no competing interests exist.
Ethical statement
No ethical statement was reported.
Funding
This study is financed by the National Natural Science Foundation of China (32270022).
Author contributions
Sein LLA conceived and designed the study; Sein LLA, Liu FY, Gou YN, Zin MN, Yu ZH, conducted the experiments; Sein LLA, Deng JX wrote the manuscript and revised.
Author ORCIDs
Sein Lai Lai Aung https://orcid.org/0009-0006-2738-5598
Feng-Yin Liu https://orcid.org/0000-0003-3114-603X
Ya-Nan Gou https://orcid.org/0009-0005-1740-4065
Zin Mar Nwe https://orcid.org/0009-0000-6376-8306
Zhi-He Yu https://orcid.org/0000-0001-9477-4135
Jian-Xin Deng https://orcid.org/0000-0001-7304-5603
Data availability
All of the data that support the findings of this study are available in the main text.
References
- Andrew M, Peever TL, Pryor BM. (2009) An expanded multilocus phylogeny does not resolve morphological species within the small-spored Alternaria species complex. Mycologia 101(1): 95–109. 10.3852/08-135 [DOI] [PubMed] [Google Scholar]
- Aung SLL, Liu HF, Pei DF, Lu BB, Oo MM, Deng JX. (2020) Morphology and molecular characterization of a fungus from the Alternariaalternata species complex causing black spots on Pyrussinkiangensis (Koerle pear). Mycobiology 48(3): 233–239. 10.1080/12298093.2020.1745476 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Berbee ML, Pirseyedi M, Hubbard S. (1999) Cochliobolus phylogenetics and the origin of known, highly virulent pathogens, inferred from ITS and glyceraldehyde-3-phosphate dehydrogenase gene sequences. Mycologia 91(6): 964–977. 10.1080/00275514.1999.12061106 [DOI] [Google Scholar]
- Carbone I, Kohn LM. (1999) A method for designing primer sets for speciation studies in filamentous ascomycetes. Mycologia 91(3): 553–556. 10.1080/00275514.1999.12061051 [DOI] [Google Scholar]
- Chen X, Chen EM, Zhao GQ. (1993) Research notes on leaf blight, brown spot, and leaf spot of watermelon. China Vegetables 6: 37–38. [in Chinese] 10.19928/j.cnki.1000-6346.1993.06.014 [DOI] [Google Scholar]
- Chun J. (1995) Computer assisted classification and identification of Actinomycetes. Doctoral dissertation, Newcastle University.
- Gou YN, Aung SLL, Htun AA, Huang CX, Deng JX. (2022) Alternaria species in section Alternaria associated with Iris plants in China. Frontiers in Microbiology 13: 1036950. 10.3389/fmicb.2022.1036950 [DOI] [PMC free article] [PubMed]
- Hall TA. (1999) Bioedit: A user-friendly biological sequence alignment editor and analysis program for Windows 95/98/NT. Nucleic Acids Symposium Series 41: 95–98. 10.1021/bk-1999-0734.ch008 [DOI] [Google Scholar]
- Hong SG, Cramer RA, Lawrence CB, Pryor BM. (2005) Alt a 1 allergen homologs from Alternaria and related taxa: Analysis of phylogenetic content and secondary structure. Fungal Genetics and Biology 42(2): 119–129. 10.1016/j.fgb.2004.10.009 [DOI] [PubMed] [Google Scholar]
- Jeewon R, Hyde KD. (2016) Establishing species boundaries and new taxa among fungi: Recommendations to resolve taxonomic ambiguities. Mycosphere 7(11): 1669–1677. 10.5943/mycosphere/7/11/4 [DOI] [Google Scholar]
- Kgatle MG, Truter M, Ramusi TM, Flett B, Aveling TAS. (2018) Alternariaalternata, the causal agent of leaf blight of sunflower in South Africa. European Journal of Plant Pathology 151(3): 677–688. 10.1007/s10658-017-1402-7 [DOI] [Google Scholar]
- Lawrence DP, Gannibal PB, Peever TL, Pryor BM. (2013) The sections of Alternaria: Formalizing species-group concepts. Mycologia 105(3): 530–546. 10.3852/12-249 [DOI] [PubMed] [Google Scholar]
- Lawrence DP, Gannibal PB, Dugan FM, Pryor BM. (2014) Characterization of Alternaria isolates from the infectoria species group and a new taxon from Arrhenatherum, Pseudoalternariaarrhenatheria sp. nov. Mycological Progress 13(2): 257–276. 10.1007/s11557-013-0910-x [DOI] [Google Scholar]
- Lawrence DP, Rotondo F, Gannibal PB. (2016) Biodiversity and taxonomy of the pleomorphic genus Alternaria. Mycological Progress 15(1): 1–22. 10.1007/s11557-015-1144-x [DOI]
- Li J, Phookamsak R, Jiang H, Bhat DJ, Camporesi E, Lumyong S, Kumla J, Hongsanan S, Mortimer PE, Xu J, Suwannarach N. (2022) Additions to the Inventory of the Genus AlternariaSectionAlternaria (Pleosporaceae, Pleosporales) in Italy. Journal of Fungi (Basel, Switzerland) 8(9): 898. 10.3390/jof8090898 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Li JF, Jiang HB, Jeewon R, Hongsanan S, Bhat DJ, Tang SM, Lumyong S, Mortimer PE, Xu JC, Camporesi E, Bulgakov TS, Zhao GJ, Suwannarach N, Phookamsak R. (2023) Alternaria: Update on species limits, evolution, multi-locus phylogeny, and classification. Studies in Fungi 8(1): 1–61. 10.48130/SIF-2023-0001 [DOI] [Google Scholar]
- Liu YJ, Whelen S, Hall BD. (1999) Phylogenetic relationships among ascomycetes: evidence from an RNA polymerse II subunit. Molecular Biology and Evolution 16(12): 1799–1808. 10.16175/j.cnki.1009-4229.2014.02.032 [DOI] [PubMed] [Google Scholar]
- Liu FY, Gou YN, Liu TY, Huang CX, Deng JX. (2022) Cucumissativus and Ipomoeapurpurea: New hosts for Alternariahydrangeae in China. Journal of Phytopathology 171(1): 48–56. 10.1111/jph.13154 [DOI] [Google Scholar]
- Ma GP, Bao S, Zhao J, Sui Y, Wu X. (2021) Morphological and Molecular Characterization of Alternaria Species Causing Leaf blight on Watermelon in China. Plant Disease 105(1): 60–70. 10.1094/PDIS-01-20-0130-RE [DOI] [PubMed] [Google Scholar]
- Maheswari CU, Sankaralingam A. (2010) Role of toxin produced by Alternariaalternata in leaf blight of watermelon and its degradation by biocontrol agents. Archiv für Phytopathologie und Pflanzenschutz 43(1): 41–50. 10.1080/03235400701652409 [DOI] [Google Scholar]
- Maoto MM, Beswa D, Jideani AI. (2019) Watermelon as a potential fruit snack. International Journal of Food Properties 22(1): 355–370. 10.1080/10942912.2019.1584212 [DOI] [Google Scholar]
- Nees von Esenbeck CG. (1816) Das System der Pilze und Schwamme. Stahelschen Buchhandlung, Wurzburg, Germany, 329 pp. 10.5962/bhl.title.110007 [DOI] [Google Scholar]
- Norphanphoun C, Hongsanan S, Bhat JD, Kuo CH, Hyde KD. (2021) Ficusmicrocarpa (Moraceae) and Kandeliacandel (Rhizophoraceae), Two New Host Records for Alternariagaisen from Taiwan. Warasan Khana Witthayasat Maha Witthayalai Chiang Mai 48(6): 1478–1499. http://epg.science.cmu.ac.th/ejournal [Google Scholar]
- Nylander JA. (2004) MrModeltest 2.0. Program distributed by the author. Evolutionary Biology Centre, Uppsala University, Sweden.
- Posada D, Crandall KA. (1998) Model test: Testing the model of DNA substitution. Bioinformatics (Oxford, England) 14(9): 817–818. 10.1093/bioinformatics/14.9.817 [DOI] [PubMed] [Google Scholar]
- Poursafar A, Ghosta Y, Orina AS, Gannibal PB, Javan-Nikkhah M, Lawrence DP. (2018) Taxonomic study on Alternaria sections of Infectoriae and Pseudoalternaria associated with black (sooty) head mold of wheat and barley in Iran. Mycological Progress 17(7): 343–356. 10.1007/s11557-017-1358-1 [DOI] [Google Scholar]
- Pryor BM, Bigelow DM. (2003) Molecular characterization of Embellisia and Nimbya species and their relationship to Alternaria, Ulocladium and Stemphylium. Mycologia 95(6): 1141–1154. 10.1080/15572536.2004.11833024 [DOI] [PubMed]
- Pryor BM, Gilbertson RL. (2000) Molecular phylogenetic relationships amongst Alternaria species and related fungi based upon analysis of nuclear ITS and mt SSU rDNA sequences. Mycological Research 104(11): 1312–1321. 10.1017/S0953756200003002 [DOI] [Google Scholar]
- Qiang X, Sun Z, Li X, Li S, Yu Z, He J, Li Q, Han L. (2024) The impacts of planting patterns combined with irrigation management practices on soil water content, watermelon yield and quality. Agroforestry Systems 98(5): 979–994. 10.1007/s10457-024-00967-y [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rambaut A. (2016) FigTree v.1.4.3 2006–2016. Tree figure drawing Tool. Oline publication. Institute of Evolutionary Biology, University of Edinburgh.
- Raven PH, Wu ZY. (2022) Flora of China, Volume 19 - Cucurbitaceae through Valerianaceae with Annonaceae and Berberidaceae. Missouri Botanical Garden Press 19: 1.
- Romain BBND, Hassan O, Kim JS, Chang T. (2022) Alternariakoreana sp. nov., a new pathogen isolated from leaf spot of ovate-leaf Atractylodes in South Korea. Molecular Biology Reports 49(1): 413–420. 10.1007/s11033-021-06887-9 [DOI] [PubMed] [Google Scholar]
- Ronquist F, Teslenko M, Van Der Mark P, Ayres DL, Darling A, Höhna S, Larget B, Liu L, Suchard MA, Huelsenbeck JP. (2012) MrBayes 3.2: Efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology 61(3): 539–542. 10.1093/sysbio/sys029 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Runa F, Park MS, Pryor BM. (2009) Ulocladium systematics revisited: Phylogeny and taxonomic status. Mycological Progress 8(1): 35–47. 10.1007/s11557-008-0576-y [DOI] [Google Scholar]
- Simmons EG. (1992) Alternaria taxonomy: current status, viewpoint, challenge. Alternaria biology, plant diseases and metabolites. Elsevier Science Publishers, Amsterdam, 1–35.
- Simmons EG. (2007) Alternaria: An identification manual, CBS Biodiversity Series 6. Centraalbureau voor Schimmelcultures, Utrecht.
- Stamatakis A, Hoover P, Rougemont J. (2008) A rapid bootstrap algorithm for the RAxML web servers. Systematic Biology 57(5): 758–771. 10.1080/10635150802429642 [DOI] [PubMed] [Google Scholar]
- Sun K, Ding M, Fu C, Li P, Li T, Fang L, Xu J, Zhao Y. (2023) Effects of dietary wild bitter melon (Momordicacharantiavar.abbreviate Ser.) extract on glucose and lipid metabolism in HFD/STZ-induced type 2 diabetic rats. Journal of Ethnopharmacology 306(116154): 1–10. 10.1016/j.jep.2023.116154 [DOI] [PubMed] [Google Scholar]
- Swofford DL. (2002) PAUP, Phylogenetic analysis using parsimony (and other methods). Version 4.0b10. Sinauer Associates, Sunderland, MA.
- Tamura K, Stecher G, Kumar S. (2021) MEGA11: Molecular Evolutionary Genetics Analysis Version 11. Molecular Biology and Evolution 38(7): 3022–3027. 10.1093/molbev/msab 120 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wani AA, Sogi DS, Singh P, Wani IA, Shivhare US. (2011) Characterisation and functional properties of watermelon (Citrulluslanatus) seed proteins. Journal of the Science of Food and Agriculture 91(1): 113–121. 10.1002/jsfa.4160 [DOI] [PubMed] [Google Scholar]
- Watanabe M, Lee K, Goto K, Kumagai S, Sugita-Konishi Y, Hara-Kudo Y. (2010) Rapid and effective DNA extraction method with bead grinding for a large amount of fungal DNA. Journal of Food Protection 73(6): 1077–1084. 10.4315/0362-028X-73.6.1077 [DOI] [PubMed] [Google Scholar]
- White TJ, Bruns T, Lee S. (1990) Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. In: Innis MA, Gelfand DH, Sninsky JJ. (Eds) PCR Protocols: A Guide to Methods and Applications.Academic Press, 315–322. 10.1016/B978-0-12-372180-8.50042-1 [DOI]
- Woudenberg JHC, Groenewald JZ, Binder M, Crous PW. (2013) Alternaria redefined. Studies in Mycology 75(1): 171–212. 10.3114/sim0015 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Woudenberg JHC, Truter M, Groenewald JZ, Crous PW. (2014) Large-spored Alternaria pathogens in section Porri disentangled. Studies in Mycology 79(1): 1–47. 10.1016/j.simyco.2014.07.003 [DOI] [PMC free article] [PubMed] [Google Scholar]
- Woudenberg JHC, Seidl MF, Groenewald JZ, De Vries M, Stielow JB, Thomma BP HJ, Crous PW. (2015) Alternaria section Alternaria: Species, formae speciales or pathotypes? Studies in Mycology 82: 1–21. 10.1016/j.simyco.2015.07.001 [DOI] [PMC free article] [PubMed]
- Xu Z, Chang L. (2017) Cucurbitaceae. In: Identification and Control of Common Weeds. Springer, Singapore Volume 3: 417–432. 10.1007/978-981-10-5403-7_18 [DOI] [Google Scholar]
- Zhang TY. (2003) Flora Fungorum Sinicorum-Alternaria 16(1): 104–106. [In Chinese]
- Zhao J, Bao SW, Ma GP, Wu XH. (2016a) Characterization of Alternaria species associated with muskmelon foliar diseases in Beijing municipality of China. Journal of General Plant Pathology 82(1): 29–32. 10.1007/s10327-015-0631-x [DOI] [Google Scholar]
- Zhao J, Bao SW, Ma GP, Wu XH. (2016b) Characterization of Alternaria species associated with watermelon leaf blight in Beijing municipality of China. Journal of Plant Pathology 98(1): 135–138. [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
All of the data that support the findings of this study are available in the main text.



