Wild rice: unlocking the future of rice breeding

Summary

Germplasm resources serve as the foundations of advancements in breeding and are crucial for maintaining food security. Wild rice species of the genus Oryza include rich sources of genetic diversity and high adaptability, making them a substantial resource for rice breeding. The discovery of wild‐type cytoplasmic male sterility resources enabled the achievement of the ‘three lines’ goal in hybrid rice, significantly increasing rice yields. The application of resistance alleles from wild rice enables rice production to withstand losses caused by stress. Reduced genetic diversity due to rice breeding poses a significant limitation to further advances and can be alleviated through a systematic use of wild genetic resources that integrate geographic, climatic and environmental data of the original habitat, along with extensive germplasm collection and identification using advanced methods. Leveraging technological advancements in plant genomics, the understanding of genetic mechanisms and the application of artificial intelligence and gene editing can further enhance the efficiency and accuracy of this process. These advancements facilitate rapid isolation and functional studies of genes, and precise genome manipulation. This review systematically summarizes the utilization of superior genes and germplasm resources derived from wild rice sources, while also exploring the collection, conservation, identification and utilization of further wild rice germplasm resources. A focus on genome sequencing and biotechnology developments is leading to new breeding and biotechnology opportunities. These new opportunities will not only promote the development of rice varieties that exhibit high yields, superior stress resistance and high quality but also expand the genetic diversity among rice cultivars.

Introduction

The genus Oryza L., belonging to the subfamily Oryzoideae of the Poaceae Barnhart family, can be traced back ~15 million years in Asia. The genus Oryza may have first originated in the tropical and subtropical regions of Southeast Asia (Vaughan, 1989). The wetland environments in this area provided favourable conditions for the growth, reproduction and evolution of Oryza species. The Oryza have significant economic and ecological value, especially Asian and African rice, which are major global food crops. The genus Oryza comprises 24 species, encompassing 2 cultivated and 22 wild rice species (Figure 1a; Ge et al., 1999; Wing et al., 2018). The two cultivated rice species are Asian cultivated rice (Oryza sativa L.) and African cultivated rice (Oryza glaberrima Steud.; Figure 1a). In the past half‐century, continuous efforts have been devoted to understanding the genomic composition and relationships among rice species. The 22 wild rice species can be categorized into 11 distinct chromosome groups based on chromosome karyotype analysis, encompassing six diploid types (AA, BB, CC, EE, FF and GG) and five allotetraploid types (BBCC, CCDD, HHJJ, HHKK and KKLL) (Figure 1a; Ge et al., 1999; Lu et al., 2009; Wing et al., 2018; Zou et al., 2008). The 22 wild rice species are primarily distributed across 77 countries and regions in Asia, Africa, Australia, the Americas and other tropical and subtropical areas (Wing et al., 2018). Based on the degree of gene exchange with cultivated rice, rice genera gene sources have been categorized into three classes: primary gene sources (GP‐1), secondary gene sources (GP‐2) and tertiary gene sources (GP‐3) (Figure 1b; Harlan and De Wei, 1971). According to Harlan and De Wet's definition of crop primary gene sources, Asian and African cultivated rice and their ancestors in cultivated rice from the primary gene pool, which includes two parts: O. sativa, and the current descendants of its ancestors O. rufipogon Griff. and O. nivara Sharma et Shastry; and O. glaberrima and its wild relative O. barthii A. Chev. The genetic resources of these primary gene sources will most easily provide transferable beneficial genes for the further improvement and improvement of cultivated rice varieties (Lu, 1998). The secondary gene sources include germplasm resources of AA genome species other than cultivated rice and its progenitor species, which are more closely related to cultivated rice but cannot produce normal fertile progeny through free hybridization. The tertiary gene sources comprise species from outside the AA genome group within the genus Oryza, as well as other germplasm resources in the rice tribe that are distantly related to cultivated rice. These genes can only be transferred to cultivated rice using special biotechnological and genetic engineering methods, as natural gene exchange is mostly not feasible (Brar and Khush, 1997).

Figure 1.

Phylogenetic relationships, classification and geographic distribution of species in the genus Oryza. (a) Phylogenetic relationships among the species of the genus Oryza (Lu, 1998). (b) Taxonomy and geographic distribution of species in the genus Oryza.

The Oryza genus has given rise to Asian cultivated rice (O. sativa; Vaughan et al., 2003), which serves as the staple food for over half of the global population and plays a crucial role in ensuring global food security. Its total production ranks third among crops in the world. Wild rice, the precursor of cultivated rice, has evolved significant genetic diversity and robust environmental adaptability through prolonged natural selection. It preserves genetic resources absent or lost in cultivated rice, including genes for high yield and resistance to bacterial leaf blight, rice blast, drought and cold stress. Wild rice serves as a valuable genetic resource for enhancing rice varieties (Yang et al., 2023). Germplasm collection of wild rice began in the late 1950s (Morishima, 2002). In the early 1970s, in response to the spread of the Green Revolution varieties, international efforts to collect local rice germplasm resources began. Subsequently, these efforts expanded to more extensive collections in rice gene banks (Vaughan et al., 2003). In China, Yuan Longping, the celebrated Chinese rice expert renowned as the ‘Father of Hybrid Rice’, successfully hybridized rice using a wild rice plant from Hainan, China, in 1973. This breakthrough marked the onset of the ‘second green revolution’ in rice production, boosting yields by 20% (Yuan, 1986). China was an early adopter of wild rice resources for rice hybrid breeding. In the 1930s, Mr. Ding Ying, a rice cultivation pioneer, created Zhongshan No. 1 by crossing cultivated rice with common wild rice. This variety exhibits strong resistance to pests, diseases, stress and wide adaptability while enhancing yields, setting a precedent for Chinese rice hybrid breeding (Li et al., 2009). In 1970, Yuan Longping's team, led by Li Bihu, identified male‐sterile strains in common wild rice for the first time, enabling the successful implementation of ‘three‐line matching’ in 1973 (Yuan, 1986). Since the 1970s discovery of cytoplasmic male sterile (CMS) resources in wild rice, China has selected numerous exceptional sterile lines. These resources have yielded various sterile lines like Wild abortive‐type, Honglian‐type, Gambiaka and Dissi‐type, D‐type, K‐type, Boro II‐type and Maxie‐type, contributing significantly to hybrid rice development. These lines have found wide application in developing super‐hybrid rice, leading to a substantial increase in rice yields. However, due to significant genetic differences between distant wild rice and cultivated varieties, issues related to reproductive isolation, poor embryo development and hybrid progeny instability may arise. Researchers have addressed these challenges by employing genetic transformation, embryo rescue, protoplast fusion, anther culture and gene‐editing techniques to transfer beneficial genes from select wild rice resources. Here, we highlight the significance of wild rice as a valuable resource for rice breeding and emphasize the potential of genome sequencing and biotechnology for unravelling genetic diversity, discovering novel genes and enhancing rice varieties. By integrating these resources and technologies, we can diversify rice varieties, and improve their yield, resistance and quality to address food security and sustainable agricultural development challenges.

Use of biotic stress tolerance genes from wild rice

Wild rice has played a pivotal role in enhancing rice biotic stress tolerance genes for improved productivity and stability. Notably, several rice blast resistance genes, such as the new alleles of Pirf2‐1(t) (Utami et al., 2008), Pi40(t) (Jeung et al., 2007), Pi9 (Qu et al., 2006) and Pi54rh (Das et al., 2012), have been identified from wild rice varieties like O. rufipogon, O. glumaepatula Steud., O. australiensis Domin., O. minuta J.S. Presl. ex C.B. Presl. and O. rhizomatis Vaughan, respectively (Figure 2). Among these genes, the new alleles of Pi9 from O. minuta and Pi54rh from O. rhizomatis exhibit broad‐spectrum resistance and are extensively utilized in breeding (Das et al., 2012; Qu et al., 2006). Furthermore, the new alleles of leaf blight resistance genes Xa21, Xa23, Xa27 and xa41(t), from wild rice (Figure 2; Chen et al., 2020; Xing et al., 2021; Yang et al., 2022), have been cloned. Xa21, in particular, was the first gene cloned from wild rice with important functions and has gained widespread use in global rice breeding programmes to combat leaf blight (Figure 2; Yang et al., 2022). Moreover, the grassy dwarf disease resistance gene Gsv, isolated from Oryza nivara (wild rice), was introduced into IR24 and other rice varieties, rendering all IR series varieties resistant to grassy dwarf disease (Li et al., 2014). Additionally, at least 20 quantitative trait loci (QTLs)/genes (~40%) associated with rice planthopper resistance have been identified in wild rice varieties. For instance, the new alleles of Bph14, Bph18 and bph29 have been cloned from O. officinalis Wall ex Watt, O. australiensis and O. rufipogon, respectively (Figure 2, Table 1). The acquisition of resistance genes from wild rice, specifically for rice blast, leaf blight, grass clump dwarf disease and rice planthopper, has substantially bolstered rice's resistance to these pests and diseases, thereby reducing the use of pesticides, and ultimately promoting food safety.

Figure 2.

Genes of wild rice origin used in cultivated rice breeding. (a) Genes that have been cloned in wild rice. (b) Proportion of genes that have been applied in various traits cloned in wild rice. (c) Distribution of genes that have been cloned in wild rice among species of the genus Oryza.

Table 1.

Useful genes that have been cloned in wild rice

ID	Gene	GP	Traits	Reference
1	Xa23	GP‐1	Biotic stress	(Wang et al., 2015a)
2	Xa30	GP‐1	Biotic stress	(Cheema et al., 2008)
3	Pirf2‐1(t)	GP‐1	Biotic stress	(Utami et al., 2008)
4	bph18(t)	GP‐1	Biotic stress	(Jena et al., 2006)
5	bph29	GP‐1	Biotic stress	(Wang et al., 2015b)
6	bph19(t)	GP‐1	Biotic stress	(Chen et al., 2006)
7	Gm‐6(t)	GP‐1	Biotic stress	(Katiyar et al., 2001)
8	bph24(t)	GP‐1	Biotic stress	(Wang et al., 2021)
9	yId1.1	GP‐1	Production	(Song et al., 2005)
10	yld2.1	GP‐1	Production	(Swamy et al., 2014)
11	SH4	GP‐1	Production	(Li et al., 2006)
12	PROG1	GP‐1	Production	(Jin et al., 2008, Tan et al., 2008)
13	SHAT1	GP‐1	Production	(Zhou et al., 2012)
14	qSH1	GP‐1	Production	(Konishi et al., 2006)
15	qGY11‐2	GP‐1	Production	(Li et al., 2002)
16	qGYP‐2‐1	GP‐1	Production	(Chen, 2010)
17	qGY2‐1	GP‐1	Production	(He et al., 2006)
18	qGYP‐1‐1	GP‐1	Production	(Jing et al., 2010)
19	qGYP‐3‐1	GP‐1	Production	(Jing et al., 2010)
20	HTH5	GP‐1	Abiotic stresses	(Cao et al., 2022)
21	SUB1A‐1	GP‐1	Abiotic stresses	(Lin et al., 2023)
22	qRLT1‐1	GP‐1	Abiotic stresses	(Liu et al., 2003)
23	qRLT6‐1	GP‐1	Abiotic stresses	(Liu et al., 2003)
24	qST1.2	GP‐1	Abiotic stresses	(Quan et al., 2017)
25	qST6	GP‐1	Abiotic stresses	(Quan et al., 2017)
26	Wx	GP‐1	Quality	(Yamanaka et al., 2004)
27	GIF1	GP‐1	Quality	(Wang et al., 2008)
28	Xa21	GP‐2	Biotic stress	(Song et al., 1995)
29	Pi68(t)	GP‐2	Biotic stress	(Devi et al., 2020)
30	gl9	GP‐2	Production	(Lin et al., 2023a,b)
31	EP4	GP‐2	Quality	(Zhang et al., 2015)
32	Bph13(t)	GP‐3	Biotic stress	(Jena and Kim, 2010)
33	Bph14	GP‐3	Biotic stress	(Hu et al., 2017)
34	Bph20(t)	GP‐3	Biotic stress	(Rahman et al., 2009)
35	Bph21(t)	GP‐3	Biotic stress	(Rahman et al., 2009)
36	Bph23(t)	GP‐3	Biotic stress	(Hou et al., 2011)
37	Bph15	GP‐3	Biotic stress	(Yang et al., 2004)
38	Bph18	GP‐3	Biotic stress	(Ji et al., 2016)
39	Bph10	GP‐3	Biotic stress	(Jena et al., 2006)
40	Bph12(t)	GP‐3	Biotic stress	(Yang et al., 2002)
41	Xa36	GP‐3	Biotic stress	(Miao et al., 2010)
42	Xa27	GP‐3	Biotic stress	(Gu et al., 2004)
43	Xa29	GP‐3	Biotic stress	(Tan et al., 2004, 2004)
44	Xa32	GP‐3	Biotic stress	(Zheng et al., 2009)
45	Xa35	GP‐3	Biotic stress	(Guo et al., 2010)
46	xa32	GP‐3	Biotic stress	(Zhang et al., 2009)
47	Wbph7(t)	GP‐3	Biotic stress	(Tan et al., 2004a)
48	Wbph8(t)	GP‐3	Biotic stress	(Tan et al., 2004b)
49	bph11	GP‐3	Biotic stress	(Hirabayashi et al., 1999)
50	bph12	GP‐3	Biotic stress	(Hirabayashi et al., 1999)
51	Pi54rh	GP‐3	Biotic stress	(Das et al., 2012)
52	Pi40(t)	GP‐3	Biotic stress	(Jeung et al., 2007)
53	Pi9	GP‐3	Biotic stress	(Qu et al., 2006)

Use of abiotic stress tolerance genes from wild rice

Wild rice genes that confer adaptation and tolerance to abiotic stresses, including high temperature, salinity, drought and low temperature, have been harnessed in rice breeding. HTH5, derived from the high‐temperature‐tolerant allele of common wild rice (O. rufipogon), increased japonica rice's setting rate by 30% at 38°C under high‐temperature stress (Cao et al., 2022). O. rufipogon offers valuable genetic resources for mitigating high‐temperature‐induced rice sterility. Soil salinization poses a serious threat to the rice industry (Ganie et al., 2019). Studies demonstrate that wild rice genes notably enhance salt tolerance in cultivated rice (Quan et al., 2018). A study of a backcross recombinant inbred line (RIL) population of indica rice 9311 with O. longistaminata A. Chev. et Roehr. identified 27 QTLs related to salt tolerance were identified, with 18 originating from O. longistaminata (Yuan et al., 2022). The study by Prusty et al demonstrated that wild species such as O. alta, O. latifolia, O. coarctata, O. rhizomatis, O. eichingeri, O. minuta and O. grandiglumis employ tissue tolerance mechanisms to manage salt stress (Prusty et al., 2018). Drought is one of the major threats to agricultural production, and wild rice germplasm hosts numerous drought‐tolerant genetic resources. Alleles from Dongxiang wild rice (O. rufipogon) can enhance drought tolerance in hybridized rice, with 11 QTLs linked to drought tolerance (Zhou, 2005). Notably, the drought tolerance gene DROT1 likely originated in wild rice (Sun et al., 2022). Wild rice, primarily found in warm, humid tropical or subtropical regions, has evolved to become resilient to cold environments in northern regions. Dongxiang wild rice, the northernmost known wild rice, exhibits robust cold tolerance and harbours abundant cold‐tolerant genes. Although the genetic features of Dongxiang wild rice resemble those of wild rice, limited research methods and experimental approaches constrain their exploration. Nevertheless, these robust cold‐tolerant genes are crucial for improving cold resistance. The genetic resources within wild rice germplasm are invaluable for enhancing the stress tolerance of cultivated rice. Nonetheless, there is a scarcity of studies and practical applications for leveraging these resources to augment rice's resistance to abiotic stressors such as high temperature, salinity, drought and cold. To address challenges such as soil salinization, drought, high temperature and cold and thereby contribute to food security, it is imperative to thoroughly explore and breed stress tolerance genes within wild rice germplasm resources.

The use of genes for yield and quality from wild rice

The breeding of high‐yielding rice has always been the primary goal pursued in rice breeding. The yield of rice is controlled by three key components: the number of effective panicles, the number of grains per panicle and grain weight (Xing and Zhang, 2010). Notably, multiple genes have been identified in the regulation of yield, plant architecture (e.g. PROG1, Tan et al., 2008) and grain shattering (e.g. SH4, qSH1, SHAT1 and gl9; Li et al., 2006; Lin et al., 2022) during rice improvement and domestication. O. rufipogon, the ancestor of O. sativa (Wang et al., 2018), possesses numerous yield‐regulating QTLs. The discovery and isolation of the PROG1 (PROG7 locus in African cultivated rice) from wild rice holds great significance in exploring the molecular basis of rice evolution and plant architecture regulation (Figure 2; Tan et al., 2008). The PROG1 gene mutation (prog1) during rice evolution was pivotal in the transition from the prostrate growth of wild rice to the erect growth of cultivated rice, significantly improving plant structure, grain count and overall yield. Genes associated with shattering properties like SH4, qSH1 and SHAT1 directly impact grain yield (Li et al., 2006; Zhang et al., 2009; Zhou et al., 2012; Figure 2). In Dongxiang wild rice (O. rufipogon), two high‐yield QTLs, qGY2‐1 and qGY11‐2, located on chromosomes 2 and 11, respectively, increased the yield of Gui Chao 2 by 25.9% and 23.2% per plant, respectively (Li et al., 2002). The qSTGL8.0 was identified from the extremely large stigma trait in O. longistaminata, which increased out‐crossing rate and hybrid seed production (Prahalada et al., 2021). Additionally, the gl9 from O. glumaepatula contributed to slender rice kernels, reduced chalkiness and increased thousand‐kernel grain weight (Figure 2; Lin et al., 2022). The process of rice evolution and domestication emphasizes yield enhancement. To meet the needs of a hungry world, grain morphology has been optimized and thousand‐grain weight increased (Doebley et al., 2006).

During the long domestication process of wild rice, humans gave priority to the yield of rice, but with the improvement of people's living standards and the changing of consumption habits, the demand for high‐quality rice is increasing. Quality traits encompass protein, starch, amino acids and microelements. Wild rice is rich in minerals, vitamins, proteins, starch, dietary fibre and antioxidant phytochemicals, while also being low in fat (Surendiran et al., 2014). Currently, new alleles of Wx and GIF1 related to rice quality have been identified from wild rice (Figure 2; Wang et al., 2008). The Wx gene, located on chromosome 6, regulates amylose content and encodes granular starch synthetase. GIF1, which encodes a cell wall transformation enzyme and is located on chromosome 4, controls amylose content and grain filling (Wang et al., 2008). Although the discovery of these genes has bolstered efforts to enhance modern rice quality (Surendiran et al., 2014; Wang et al., 2008), research on quality improvement genes in wild rice is limited. Wild rice garners global attention due to its antioxidant properties and potential health benefits. Compared to cultivated rice, wild rice offers higher protein content, lower fat content and abundant dietary fibre and essential amino acids, which are associated with chronic disease prevention (Chu et al., 2019). Therefore, exploring antioxidants in wild rice and developing related food products may contribute to the prevention of cardiovascular diseases, cancer, autoimmune disorders and inflammatory diseases.

Genome sequencing of wild rice germplasm resources is pivotal for understanding genetic diversity, genome structure and functional genes. By performing whole‐genome resequencing on 50 samples of both wild and cultivated rice samples, researchers uncovered that O. sativa ssp. indica is closely related to O. nivara, whereas O. sativa ssp. japonica is related to O. rufipogon, particularly Dongxiang wild rice in the Yangtze River Basin (Hou et al., 2011; Huang et al., 2012). By analysing 446 wild rice samples with varying geographical distribution and 1083 cultivated rice genomes, a detailed genetic variation map was created. This study offers profound insights into rice genome variation. Furthermore, the resequencing of 20 cultivated rice and 94 wild rice samples from Africa indicated that O. glaberrima closely resembles a wild rice population (OB‐V) along the Niger River, which is a potential centre of rice domestication in Africa (Wang et al., 2014). Comparative genomic analysis of 13 different rice species within the Oryza genus uncovered the emergence of new genetic elements, such as transposons and various genes, driving rapid species diversification without significant chromosomal changes. This discovery elucidates the underlying phylogenetic mechanisms within the Oryza genus which have evolved over time (Stein et al., 2018). Analysis of domesticated rice has shown that only two functional distinct chloroplast genomes are present (Moner et al., 2020), suggesting two maternal domestications in O. sativa, and indicating that the domestication of other chloroplast genotypes could potentially introduce new genetic variation. In conclusion, these findings provide a crucial theoretical foundation for studying rice domestication and evolutionary patterns, assessing genetic diversity in germplasm resources and accurately mining genes associated with complex traits.

With the gradual improvement in germplasm collection, we anticipate discovering additional genes that impact rice grain yield and quality. The in‐depth examination of wild rice genomes and molecular mechanisms, coupled with modern genetic and gene editing techniques, enhances our comprehension of wild rice domestication and its relevance to grain yield and quality traits. This will provide a robust scientific foundation for rice breeding and future genetic enhancements.

Prospects for the utilization of wild rice germplasm resources

The wild species related to cultivated rice have rich genetic diversity and strong environmental adaptability through long‐term natural selection and provide the germplasm resources such as resistance to white leaf blight, blast, drought and cold, needed for the genetic improvement of cultivated rice and are a valuable gene pool for the improvement of cultivated rice. However, the utilization of desirable wild rice genes remains limited, emphasizing the need for further comprehensive exploration and utilization.

Enhancing germplasm resource utilization by expanding scientific collections of wild rice

Despite the existence of a wide range of wild rice germplasm collections, some populations remain uncollected. For example, within China's collected wild rice germplasm, varieties from other countries account for <10%, significantly below the global average of 45%. Additionally, the distribution and proportion of wild rice accessions from different regions are uneven (Wang et al., 2011a,b; Zhang and Yang, 2003). Studies have found that wild rice populations in different countries across South Asia, Southeast Asia and Northern Australia, may represent distinct gene pools (Cai et al., 2004; Sun and Yang, 2009; Zheng and Ge, 2010). Expanding international wild rice collections in the many countries with wild rice genetic resources, while also refining the collection methods and enhancing habitat‐related geographical, climatic and environmental data, is strategically vital. This effort holds immense significance for enriching and enhancing wild rice genetic resources.

Enhancing phenotypic identification of wild rice to increase the utilization of genetic resource

Conventional morphological traits primarily focus on characteristic parts (e.g. auricles, ligules, leaf sheaths, internodes, awns and underground stems), colour, plant shape, tillering capacity, grain fallibility and spike branching (Fan et al., 2023). While identifying phenotypes in wild rice is more straightforward at various levels, including physiological, tissue, cellular and molecular, there is limited research on evaluating the tolerance of specific wild rice varieties to biotic and abiotic stresses. To address the inefficiencies in material phenotyping, we established a multi‐level phenomics identification platform using not only visible light and near‐infrared imaging methods but also drones and robots as imaging carriers. Our platform integrates and analyses phenome data through computer vision and artificial intelligence, facilitating high‐throughput, large‐scale phenotype identification (Zheng et al., 2023). We utilized the phenome analysis platform to monitor the growth, development, adaptation to adversity, yield composition, quality formation, resistance to pests and diseases, nutrient utilization efficiency and dynamic changes in root system structure in diverse wild rice germplasm resources. This study aims to elucidate phenotypic diversity and environmental adaptability in wild rice germplasm resources, laying a strong foundation for breeding efforts by incorporating environmental factors such as geography, climate and soil data.

Strengthening wild rice germplasm conservation for future genetic breeding stock of cultivated rice

The endangerment of wild rice germplasm resources stems from human production activities and the invasion of alien species. This results in a reduced genetic diversity of wild rice. Additionally, insufficient regulation and funding have degraded wild rice during in situ and ex situ conservation (Yang et al., 2023; Zhang and Yang, 2003). To safeguard wild rice germplasm, we must enhance in situ conservation and improve monitoring and early warning methods. These sites offer a secure environment for wild rice growth and reproduction. Simultaneously, bolstering biodiversity protection in these sites maintains a healthy ecological balance for wild rice in its natural habitat. In situ conservation, we need to tailor environmental conditions to the different rice species' habitats, renew seed stems and potting soil regularly and perform routine leaf‐cutting and stubble treatments (Fan et al., 2009). Expanding the scope of ex situ conservation, beyond the existing site, is crucial. Currently, only a few samples of wild rice species are in ex situ conservation, which limits the genetic diversity of wild rice. To address this, we can establish protected areas across various regions to cover more wild rice species. A combined in situ and ex situ conservation system will protect more wild rice germplasm resources, increase genetic diversity and offer more options for future genetic breeding of cultivated rice. The protection of wild rice germplasm resources is essential for food security, ecological preservation and sustainable development. Therefore, strengthening conservation awareness and active participation in wild rice protection is crucial. This not only holds significant value but also signifies our respect for nature and our responsibility for humanity's future.

Strengthening the application of wild rice breeding to fully tap its potential breeding value

Wild rice serves as a strategic reserve resource and seed ‘chip’ with attributes including disease and pest resistance, as well as tolerance to salt, drought, cold, barren conditions and other unique traits. For example, perennial rice varieties can be developed by using the characteristic of rhizome from O. longistaminata, which saves a lot of labour and input costs (Zhang et al., 2023). However, species within the Oryza genus, found in GP2 and GP3, cannot produce fertile offspring when crossed freely with cultivated rice (Harlan and De Wei, 1971). Overcoming interspecific reproductive barriers in wild rice is vital for harnessing its rich genetic resources. To address this challenge, gene editing and the development of gene‐linked molecular markers in wild rice represent pivotal advancements enabling future applications. Utilizing gene editing to disable interspecific reproductive isolation genes can enhance trait improvement in both cultivated and wild rice through hybridization. Moreover, the genetic enhancement of semi‐wild rice with lower domestication, involving knocking out genes linked to long awns, seed drop facilitation, light sensitivity, culm susceptibility, plant shape irregularities and low yield, is achievable (Hao, 2020). Accelerating wild rice breeding is feasible by identifying molecular markers closely associated with quality traits within the population (Grover and Sharma, 2016). DNA markers are essential tools for genetic analysis and breeding. Recent efforts in the development of genome‐wide InDel marker sets have opened new avenues for harnessing the genetic diversity present in AA‐ and BB‐genome wild species (Hechanova et al., 2021; Malabanan‐Bauan et al., 2023). The newly developed InDel markers may be useful for the identification of valuable genetic factors from the AA and BB‐genome wild rice species and also for transferring the identified genes/QTLs into elite variety backgrounds.

Conclusion

Biodiversity, as the repository of genetic diversity, plays a crucial role in rice production all over the world. Wild rice, a vital source for rice germplasm innovation and enhancement, offers abundant genetic resources. Sanya, Hainan Province, hosts the world's largest wild rice germplasm resource nursery (National Resource Nursery) which houses 21 wild rice species and 13 000 germplasm copies. Supported by platforms like the Global Transit Base for Plant and Animal Germplasm Resources, the National Resource Nursery has promoted the International Wild Rice Alliance and advanced the global system for protecting, researching and utilizing wild rice relatives and local rice varieties. Collaborative germplasm resource investigations, an extensive all‐around, wide‐ranging and multi‐level international exchange platform, and resource introduction and exchange have been facilitated through major international cooperation projects like the International Conference on Wild Rice. The goal is to enhance the safe preservation and efficient utilization of germplasm resources. The future holds a continued emphasis on conserving and utilizing wild rice germplasm resources to identify valuable wild rice genes for contemporary and future rice cultivation. This endeavour aims to establish a world‐class national crop germplasm resource bank, fostering new rice varieties and contributing essential genetic resources to modernized rice breeding. Our approach to conserving wild rice germplasm resources emphasizes simultaneous conservation and utilization. By studying wild rice, we can identify high‐quality genotypes for rice cultivation while respecting and safeguarding these resources to prevent misuse and over‐exploitation.

To advance the transition from traditional breeding to the highly efficient, precise and targeted Molecularly Designed Intelligent Breeding 5.0, we must intensify wild rice genomics research and tap into its exceptional gene reservoir. When combined with modern molecular marker‐assisted selection methods, we can enhance rice breeding and production more effectively (Figure 3).

Figure 3.

Infographic showing the workflow to optimize the collection, identification, conservation and utilization of wild rice and to promote the genetic improvement of cultivated rice.

Funding information

This article was supported by grants from the National Key Research and Development Program of China (2021YFD1200101), National Natural Science Foundation of China (32188102, 32350710198), the Project of Sanya Yazhou Bay Science and Technology City (SCKJ‐JYRC‐2023‐47, SKJC‐2023‐02‐001) and Hainan Province Science and Technology Special Fund (ZDYF2022XDNY260).

Conflict of interest

The authors declare that they have no conflict of interest.

Author contributions

Q.Q. conceived the manuscript; X.M.Z., Y.L.P. and J.Y.Q. drafted the manuscript; and X.M.Z., Y.L.P., J.Y.Q. and R. H. revised the manuscript. The authors read and approved the final manuscript.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author. The data are not publicly available due to privacy or ethical restrictions.