Crop wild relatives conserve favorable genetic variation that is rare or absent in cultivated crops， including alleles related to disease and insect resistance， abiotic stress tolerance， quality traits and environmental adaptation. Under climate change and increasing food security pressure， their utilization has shifted from germplasm conservation and phenotypic screening to targeted introgression， alien-segment optimization， precise evaluation of complex traits and efficient germplasm development. This review focuses on four major constraints in the use of crop wild relatives， namely difficulties in gene introgression， linkage drag， inaccurate evaluation of complex traits and slow translation from resources to breeding materials. We summarize recent progress in wide hybridization， embryo rescue， ploidy manipulation， chromosome engineering， genetic transformation， genome editing， marker-assisted selection， pangenomics， multi-omics and de novo domestication， and discuss representative cases in rice， wheat， tomato， soybean and potato. The review aims to provide references for efficient utilization of crop wild relatives and modern germplasm innovation.

Wheat wild relatives harbour rich genetic variations accumulated through natural evolution and serve as reservoirs of resistance genes against environmental stressors and vital genetic resources for breeding high-yield， high-quality wheat varieties. However， long-term breeding practices prioritizing yield-related traits and technical barriers in distant hybridization make modern wheat cultivars exhibit a narrow genetic base and leave numerous valuable genetic resources in wild relatives underutilized. Meanwhile， threats such as anthropogenic disturbances， habitat degradation and climate change have led to severe population decline or even extinction of some wild relatives， risking permanent loss of their unique genetic resources. Strengthened conservation efforts （especially in situ） are therefore urgently needed. This review systematically examines the taxonomy， geographic distribution of wheat wild relatives， the origin and domestication history of wheat and current genetic diversity； summarizes utilization of wild relatives in genetic improvement； critically analyses conservation status （in situ/ex situ）， challenges in preserving these resources and proposes science-based strategies for effective conservation and sustainable utilization. These insights aim to provide theoretical support for driving innovative development in the wheat seed industry and ensuring food security.

Maize has the closest genetic relationship with other subspecies of teosintes that belong to the same species as maize （i.e.， Zea mays）， among which two subspecies are associated with the origin of modern maize. Slightly more distantly related to maize are other teosinte species within the same genus as Zea mays. Even more distantly related are species of the genus Tripsacum. All of these serve as important sources of gene resources for maize breeding. Based on an overview of the classification and geographical distribution of maize wild relatives， this article describes the status of in situ and ex situ conservation of global germplasm resources of maize wild relatives， evaluates their utilization value in maize breeding， and reviews the history and current status of germplasm enhancement and breeding use based on these wild relatives. Finally， key directions and technical approaches are proposed for future utilization in maize breeding.

Foxtail millet （Setaria italica） is an important C₄ minor cereal crop in northern China， characterized by strong adaptability such as tolerance to drought and infertile soils. Its wild relatives harbor abundant genetic diversity and constitute an important gene pool for broadening the genetic base of cultivated foxtail millet and for breeding new cultivars with improved stress tolerance， high yield， and superior quality. Focusing on the domestication and utilization of foxtail millet and its wild relatives， we integrate archaeological and genetic evidence to summarize the origin and domestication trajectory of foxtail millet in northern China， highlighting the evolution of key domestication-related traits.Integrating recent progress in both traditional morphology and molecular phylogenetics，we elaborate on the classification of genome types within the genus Setaria and its value for resolving phylogenetic relationships among related taxa. Furthermore，we summarize the current conservation and utilization status of germplasm resources for foxtail millet and its wild relatives， noting that China has a distinct advantage in the overall number of conserved accessions，the international coverage of the resources， as well as the representativeness and depth of characterization for wild relatives， still need to be strengthened. Finally， in light of advances in genetic linkage mapping/QTL and GWAS， studies on stress tolerance and quality traits， as well as developments in transformation systems， genome editing， and molecular breeding， we discuss the potential applications of wild relatives of foxtail millet in germplasm innovation and breeding. This review provides a reference for the systematic mining of favorable genes from wild relatives of foxtail millet and their efficient utilization in breeding programs.

The development and rational use of disease-resistant varieties has been the most effective strategy for achieving high yielding and good quality in rice production. Wild rice， a valuable genetic resource due to its prolonged adaptation to survive and thrive in natural environments， retains numerous original traits that have been lost or attenuated in cultivated rice during the long-term domestication. Wild rice harbors abundant genetic diversity and offers far greater potential for mining disease-resistance genes than cultivated rice， thus serving as a crucial gene pool for rice breeding with higher disease-resistance. This review focuses on disease resistance in wild rice. We systematically describe the fundamental characteristics of disease resistance and review the identification of disease-resistant germplasm resources in three wild rice species native to China， namely Oryza rufipogon， Oryza officinalis， and Oryza granulata， against rice blast， bacterial blight， sheath blight and other diseases. We also summarize the disease-resistance genes identified for rice blast and bacterial blight， highlighting on representative genes such as Pi-gx（t） and Xa23 discovered by Chinese researchers. Notably， Xa23 has been widely deployed in rice breeding programs and industrial production， achieving remarkable economic and social benefits. Finally， we comprehensively review the application of key technologies—distant hybridization， molecular marker-assisted selection， genetic transformation， and gene editing—in developing wild rice germplasm with disease-resistance and transferring elite resistance genes into cultivated rice. Based on the current research status and technical bottlenecks， we further propose potential strategies in germplasm screening， gene mining and technological integration， aiming to provide theoretical support and tools for enhancing disease resistance in rice molecular breeding programs and for the green prevention and control of diseases in rice production.

The genus Elytrigia （Thinopyrum） exhibit outstanding disease resistance and serve as an important member of the tertiary gene pool of wheat. The exploration and application of disease-resistant genes from Elytrigia have provided critical support for the wheat improvement in disease resistance. As early as the 1920s， reports on distant hybridization between wheat and Elytrigia emerged. Over the past century， numerous disease-resistant genes have been identified in Elytrigia species and multiple disease-resistant germplasm have been developed by distant hybridization and molecular chromosome engineering and breeding of high-yielding and disease-resistant cultivars such as Xiaoyan 6， which have made significant contributions to wheat breeding and food security. This article systematically reviews the general of Elytrigia genus species， the research progress on genes resistant to common fungal diseases such as stripe rust， leaf rust， stem rust， powdery mildew， fusarium head blight， and crown rot， and summarizes advances in creating novel germplasm and breeding applications of disease-resistant genes through distant hybridization and molecular chromosome engineering. Furthermore， it discusses challenges in the exploration and application of disease-resistant genes from Elytrigia， and prospects future research directions. This review is structured into the aforementioned four sections， aiming to provide a scientific basis for in-depth analysis of the mechanisms of exogenous disease-resistant genes and enhance their utilization efficiency in wheat breeding programs.

Wild rice （Oryza rufipogon Griff.） harbors extensive genetic diversity and superior environmental adaptability， serving as an invaluable genetic materials for the genetic improvement of cultivated rice. Rice blast， caused by Magnaporthe oryzae， is categorized as a Class I agricultural pest by the Ministry of Agriculture and Rural Affairs of the People′s Republic of China. Exploiting elite resistance resources to develop broad-spectrum resistant cultivars is considered the most cost-effective and sustainable management strategy. In this study， 1018 O. rufipogon accessions collected from Guangdong， Hainan， and Guangxi of China were evaluated for resistance to rice blast using 42 predominant physiological races of M. oryzae from Sichuan， Chongqing， Guizhou， Jiangxi， Yunnan， Hubei， and Jiangsu. When challenged with the Southwest mixed isolates （from Sichuan， Guizhou， and Chongqing）， 88 accessions were resistant （R）， 34 moderately resistant （MR）， 124 moderately susceptible （MS）， and 772 susceptible （S）. Among the 122 accessions showing resistance （R and MR） to the southwest mixture， 69 （56.6%） were resistant to isolate B27 from Hubei， 81 （66.4%） to the Jiangxi mixed isolate， 111 （91.0%） to isolate Q12 from Yunnan， and 113 （92.6%） to isolate C62 from Jiangsu. Sequential screening identified 59 accessions with broad-spectrum resistance （R and MR） to all 42 predominant isolates， including 45 from Guangdong， five from Guangxi， and nine from Hainan. Notably， the frequency of broad-spectrum resistance in Hainan （22.0%） was significantly higher than in that Guangdong （5.1%） and Guangxi （5.4%）. These broad-spectrum-resistant wild rice germplasm resources represent a pivotal germplasm reservoir that underpins future investigations into rice blast resistance and accelerates the breeding of resilient cultivars.

Species of the genus Agropyron Gaertn. are not only recognized as premium perennial forages worldwide but also serve as critical exogenous donors for broadening the genetic base and improving the comprehensive traits of wheat through wide hybridization. To promote the efficient utilization of Agropyron germplasm resources， this study investigated 206 accessions of diverse origins （excluding A. mongolicum）. Ploidy levels were first identified using flow cytometry in combination with cytological observations. Subsequently， a comprehensive evaluation of tetraploid Agropyron germplasm was performed based on 16 phenotypic traits through diversity， correlation， cluster， and membership function analyses. Finally， the optimal strategy for constructing a tetraploid Agropyron core collection was screened from 384 combinations involving two genetic distances， three sampling methods， eight sampling proportions， and eight clustering methods， followed by a representativeness validation. The results indicated that the tested germplasm consisted of 187 tetraploids， 8 diploids， and 11 hexaploids. The coefficient of variation for the 16 phenotypic traits in the tetraploid accessions ranged from 15.78% to 38.26%， with an average of 24.42%. The genetic diversity index ranged from 1.58 to 1.99， with an average of 1.83， indicating high phenotypic diversity. Through systematic comparison， the strategy of “Euclidean distance + multiple cluster priority sampling +15% sampling proportion+single distance method” was identified as the optimal strategy， leading to the construction of a core collection containing 28 accessions. Multi-dimensional validation confirmed that the core collection effectively represents the genetic characteristics and population structure of the initial collection. Five elite germplasm accessions with high comprehensive scores， namely Z559， Z1511， LF112， Z1780 and LF1782， were screened out via subordinate function comprehensive evaluation. All of them were included in the core germplasm collection， which further verified the superiority of the core germplasm. In summary， the tetraploid Agropyron core collection developed in this study provides a reliable representation of the original population， offering a theoretical basis and material foundation for the preservation， evaluation， and genetic improvement of Agropyron germplasm.

Wheat powdery mildew， caused by the obligate biotrophic fungus Blumeria graminis f. sp. tritici， is a globally prevalent disease that poses a severe threat to wheat yield and quality. Breeding resistant varieties through the deployment of resistance genes is widely recognized as the most economical and effective strategy for disease management. The Pm13 gene， a broad-spectrum powdery mildew resistance gene located on chromosome 3S^l of Aegilops longissima， a wild relative of common wheat， was introduced into common wheat through wheat-Ae. longissima 3S^lchromosome translocation in the 1990s. However， the large size of the alien chromosomal segment carrying Pm13 resulted in linkage drag， which has constrained its utility in wheat breeding programs. In this study， the ph1b gene was employed to promote homoeologous recombination between Ae. longissima 3S^l#2 chromosome and wheat homoeologous group 3 chromosomes. Consequently， three powdery mildew-resistant translocation lines with minimal introgressed segments carrying Pm13 （W12-3A， W12-3G， and W12-3H） were successfully developed. Marker enrichment analysis revealed that the size of the introgressed 3S^l chromosomal segments in these translocation lines were 1.886 Mb， 699 kb， and 196 kb， accounting for only 0.24%， 0.087%， and 0.024% of the entire 3S^l chromosome， respectively. Genetic analysis of self-pollinated F₂ populations derived from these translocation lines showed that the segregation ratio of resistant to susceptible plants fitted the expected 3∶1， indicating stable inheritance of Pm13. Furthermore， agronomic evaluation of the translocation line W12-3H with the smallest introgressed 3S^l chromosome segment revealed no adverse effects on key agronomic performance traits. Resistance assessment across different genetic backgrounds demonstrated that Pm13 confers effective powdery mildew resistance in diverse wheat lines. Collectively， this study successfully developed disease-resistant Pm13 tiny-segment translocation lines with no linkage drag， providing valuable genetic resources to facilitate the efficient utilization of the Pm13 gene in wheat powdery mildew resistance breeding.

Rice blast， caused by Magnaporthe oryzae， is one of the most destructive diseases threatening rice production. Breeding and deploying resistant cultivars is a cost-effective and environmentally sustainable strategy for disease control. However， the frequent breakdown of resistance and the narrow genetic base of resistance genes remain major constraints， highlighting the need to identify new resistant germplasm. Wild rice， as a close relative of cultivated rice， harbors abundant genetic diversity shaped by natural selection and represents an important reservoir for novel blast resistance genes. Nevertheless， large-scale evaluation of blast resistance in international wild rice resources， especially those from Myanmar and Sri Lanka， remains limited. In this study， 155 wild rice accessions from China and abroad were evaluated using a detached-leaf puncture inoculation assay against a mixed inoculum comprising 16 M. oryzae physiological races from Sichuan. The tested accessions showed substantial variation in blast resistance. In total， 103 accessions were classified as resistant （R） or moderately resistant （MR）， accounting for 66.4% of all accessions， including 76 R （49.0%） and 27 MR （17.4%）. Among accessions from different origins， the proportion of R accessions from Myanmar and Sri Lanka was 57.7% and 55.6%， respectively， slightly higher than that from China （40.0% from Hainan and 50.0% from Guangxi）， and they exhibited relatively lower disease indices. Notably， the resistance frequency （R+MR） of O. nivara from Sri Lanka reached 90.0%， while most accessions from Myanmar were classified as resistant. These results indicate that wild rice accessions from Myanmar and Sri Lanka exhibited higher proportions of resistant and lower proportions of susceptible accessions. In particular. O. nivara from Sri Lanka holds great promise for mining broad-spectrum blast resistance genes and selecting resistant donors. This study provides valuable germplasm resources for broadening the genetic basis of blast resistance in rice breeding.

In order to clarify the taxonomic status of two special coix germplasm discovered in Xizang of China， their agronomic and taxonomic identification were conducted and the botanical characteristics of the new species were described and illustrated. These twogermplasms were similar to Coix aquatica， but Coix gigantea had plants erect shape； long lanceolate leaves broaden in middle part that looking like hearts， meanwhile the upper and lower layers were coarse and grows glandular hairs in leaf upper surface. Staminate inflorescences is long and thin that generating fertile pollen， enamel involucre or fruit case is pyriform or fusiform in shape， and these typical characteristics were distinguished from those of Coix aquatica. It was estimated by flow cytometry that the genome size of two Coix gigantea were 1578.85 Mb and 1807.92 Mb， whose genomes were diploid type of 2n=2x=20. Phylogenetic analysis indicated that Coix gigantea and Coix aquatica were divided into independent branches in the phylogenetic tree， exhibiting independent genetic lineages. Therefore， Coix gigantea in tegrated evidence from plant morphology， chromosome ploidy and molecular phylogeny all supports that is a newly recorded independent species of the genus in China.

To fully understand the distribution and variation patterns of wild Fagopyrum dibotrys （D. Don） Hara resources， this study conducted field investigations on seven wild populations collected from central and northeastern Yunnan， and performed a systematic diversity analysis based on phenotypic characteristics， secondary metabolites （flavonoids）， and SSR molecular markers. The results showed that the distribution density and population size of Fagopyrum dibotrys were relatively high in northeastern Yunnan， while those in central Yunnan were low and scattered， which may be related to the high degree of industrialization in central Yunnan. Wild Fagopyrum dibotrys in central and northeastern Yunnan exhibited abundant population variation and high plasticity in both phenotypic traits and secondary metabolite profiles， the coefficient of variation ranged from 2.30% to 63.86%. Genetic diversity analysis revealed that different populations possessed varied levels of genetic diversity. The expected heterozygosity of these populations ranged from 0.1435 to 0.2735， and the Shannon's information index varied from 0.2060 to 0.3985. The Ludian population showed the largest distribution density， largest population scale and optimal genetic diversity level（the expected heterozygosity was 0.2735， and Shannon's information index was 0.3985）， suggesting that it may represent a genetic diversity center of Fagopyrum dibotrys in central and northeastern Yunnan. The genetic differentiation coefficient among populations ranged from 0.0203 to 0.2006. The Zhaoyang population exhibited relatively strong genetic differentiation from other populations， which may be associated with the unique climate and geographical location of its distribution area.This study clarified the background diversity and population differentiation characteristics of wild Fagopyrum dibotrys in central and northeastern Yunnan， providing a scientific basis for the precise conservation and innovative utilization of this species.

Ratoon rice possesses multiple production advantages including higher multiple cropping index， superior grain quality， seed and labor savings， reduced water consumption and pesticide application， as well as remarkable economic benefits. Therefore， identifying and evaluating the ratooning ability of germplasm resources is particularly important for developing cultivars with strong ratooning ability. In this study， 241 chromosome segment substitution lines（CSSLs）derived from wild rice and 438 cultivated rice accessions were used as materials. Fourteen phenotypic traits were evaluated in replicated trials over two years to comprehensively assess the ratooning ability of the germplasm. The results showed that the phenotypic coefficient of variation ranged from 2.54% to 49.46% in the wild rice population， and from 4.17% to 33.06% in the cultivated rice population. Among all traits， grain yield per plant in the ratoon season exhibited the highest coefficient of variation in both populations. Correlation analysis revealed that ratooning ability was significantly or extremely significantly positively correlated with plant height， panicle length， number of productive panicles in the ratoon season and ratooning yield per plant， but significantly or extremely significantly negatively correlated with number of productive panicles and seed setting rate. This suggests that developing germplasm with strong ratooning ability requires balanced consideration of traits in both the main and ratoon crops. Five principal components with eigenvalues greater than 1 were extracted by principal component analysis， explaining a cumulative contribution rate of 75.15%. The comprehensive evaluation value for ratooning ability （D values） was obtained by integrating membership function analysis and weight assignment. The D values ranged from 0.24 to 0.74， with a mean of 0.47. Introduced accessions exhibited the best overall ratooning ability， improved cultivars and landraces were at an intermediate level， and the wild rice population showed the poorest ratooning ability but had rich genetic variation， making it suitable for QTL mapping， dissection of single-segment effects， and mining of candidate regions. Representative resources including the introduced accessions IR 83142-60 and IRRI 186， improved cultivars Shuanghuixuan 26 and Xianjinghui 6， the landrace Baike No. 5， and the wild rice line A0792 were identified and can be directly used as core parents with strong ratooning ability in breeding programs. This study clarified the genetic differences in ratooning ability among different types of rice， established a quantitative and applicable comprehensive evaluation index for ratooning ability， and provides material basis and theoretical reference for screening elite ratoon rice germplasm， parent selection， and gene mining for ratooning ability.

Oryza rufipogon Griff.， the direct ancestor of cultivated rice， is a core germplasm resource for rice genetic improvement. At present， the natural habitats of wild rice have suffered severe degradation. Moreover， the in vivo-conserved germplasm in wild rice nurseries is threatened by rice viral diseases， which severely compromised the safe preservation of wild rice resources. In this study， a tissue culture system was constructed， and axillary buds of virus-infected O. rufipogon were used as explants to achieve virus elimination. The results showed that the combination of 5 mg/L 2，4-D and 1 nmol/L OsREF1 could induce callus formation and proliferation from axillary buds， and the combination of 2 mg/L 6-BA and 0.2 mg/L NAA could induce shoot differentiation. The two-step rooting method facilitated root induction and the growth of intact and robust plantlets. RT-PCR showed that the virus-specific bands were absent in the regenerated plantlets. In conclusion， this established system could achieve virus elimination and regeneration of virus-infected O. rufipogon， and provide technical support for the safe preservation of wild rice germplasm resources.

There are three wild rice germplasm resources in China. Compared with Oryza rufipogon and Oryza officinalis， Oryza granulata exhibits more distinct scarcity and endangerment status and utmost importance in protection. At present， the research on the theory of wild rice conservation and the development of conservation technology are relatively lagging behind， and there is a lack of standardized technical guidelines， which results in insufficient support for both ex-situ and in-situ conservation. Based on the results of many years of investigation and experiments， the standard technical regulation for ex-situ conservation of Oryza granulata resources was summarized and normalized. It mainly includes the saving procedures， acquisition of germplasm samples， trial planting and observation， cataloging and organization， ex-situ conservation， planting in the field， field management， monitoring， harvesting， rejuvenation and propagation， distribution， germplasm information. Our study provides technical reference for ex-situ conservation of Oryzagranulata resources. The technical regulations are applicable to ex-situ conservation of Oryza granulata resources.