Orchardgrass (Dactylis glomerata L.), is a well-known perennial forage species; however, rust diseases have caused a noticeable reduction in the quality and production of orchardgrass. In this study, genetic diversity was assessed and the marker-trait associations for rust were examined using 18 EST-SSR and 21 SCoT markers in 75 orchardgrass accessions. A high level of genetic diversity was detected in orchardgrass with an average genetic diversity index of 0.369. For the EST-SSR and SCoT markers, 164 and 289 total bands were obtained, of which 148 (90.24%) and 272 (94.12%) were polymorphic, respectively. Results from an AMOVA analysis showed that more genetic variance existed within populations (87.57%) than among populations (12.43%). Using a parameter marker index, the efficiencies of the EST-SSR and SCoT markers were compared to show that SCoTs have higher marker efficiency (8.07) than EST-SSRs (4.82). The results of a UPGMA cluster analysis and a STRUCTURE analysis were both correlated with the geographic distribution of the orchardgrass accessions. Linkage disequilibrium analysis revealed an average r² of 0.1627 across all band pairs, indicating a high extent of linkage disequilibrium in the material. An association analysis between the rust trait and 410 bands from the EST-SSR and SCoT markers using TASSEL software revealed 20 band panels were associated with the rust trait in both 2011 and 2012. The 20 bands obtained from association analysis could be used in breeding programs for lineage selection to prevent great losses of orchardgrass caused by rust, and provide valuable information for further association mapping using this collection of orchardgrass.

While orchardgrass (Dactylis glomerata L.) is a well-known perennial forage species, rust diseases cause serious reductions in the yield and quality of orchardgrass; however, genetic mechanisms of rust resistance are not well understood in orchardgrass. In this study, a genome-wide association study (GWAS) was performed using specific-locus amplified fragment sequencing (SLAF-seq) technology in orchardgrass. A total of 2,334,889 SLAF tags were generated to produce 2,309,777 SNPs. ADMIXTURE analysis revealed unstructured subpopulations for 33 accessions, indicating that this orchardgrass population could be used for association analysis. Linkage disequilibrium (LD) analysis revealed an average r2 of 0.4 across all SNP pairs, indicating a high extent of LD in these samples. Through GWAS, a total of 4,604 SNPs were found to be significantly (P < 0.01) associated with the rust trait. The bulk analysis discovered a number of 5,211 SNPs related to rust trait. Two candidate genes, including cytochrome P450, and prolamin were implicated in disease resistance through prediction of functional genes surrounding each high-quality SNP (P < 0.01) associated with rust traits based on GWAS analysis and bulk analysis The large number of SNPs associated with rust traits and these two candidate genes may provide the basis for further research on rust resistance mechanisms and marker-assisted selection (MAS) for rust-resistant lineages.

Black barley seeds are a health-beneficial diet resource because of their special chemical composition and antioxidant properties. The black lemma and pericarp (BLP) locus was mapped in a genetic interval of 0.807 Mb on chromosome 1H, but its genetic basis remains unknown. In this study, targeted metabolomics and conjunctive analyses of BSA-seq and BSR-seq were used to identify candidate genes of BLP and the precursors of black pigments. The results revealed that five candidate genes, purple acid phosphatase, 3-ketoacyl-CoA synthase 11, coiled-coil domain-containing protein 167, subtilisin-like protease, and caffeic acid-O-methyltransferase, of the BLP locus were identified in the 10.12 Mb location region on the 1H chromosome after differential expression analysis, and 17 differential metabolites, including the precursor and repeating unit of allomelanin, were accumulated in the late mike stage of black barley. Phenol nitrogen-free precursors such as catechol (protocatechuic aldehyde) or catecholic acids (caffeic, protocatechuic, and gallic acids) may promote black pigmentation. BLP can manipulate the accumulation of benzoic acid derivatives (salicylic acid, 2,4-dihydroxybenzoic acid, gallic acid, gentisic acid, protocatechuic acid, syringic acid, vanillic acid, protocatechuic aldehyde, and syringaldehyde) through the shikimate/chorismite pathway other than the phenylalanine pathway and alter the metabolism of the phenylpropanoid-monolignol branch. Collectively, it is reasonable to infer that black pigmentation in barley is due to allomelanin biosynthesis in the lemma and pericarp, and BLP regulates melanogenesis by manipulating the biosynthesis of its precursors.

Cultivated barley (Hordeum vulgare L.) has been proven to be an economically important model plant and having large genetic diversity among the species. The effective exploitation of qualitative characters in barley can be measured by its genetic diversity and interrelationship. This study aims to determine the assessment of genetic diversity in Chinese hulless barley accessions for qualitative traits. Presently, in this study, the genetic diversity of 208 Chinese hulless barley from different Provinces of China, 111 genotypes were from the Tibet plateau, 30 Sichuan, 2 USA, 1 Canada, 12 Gansu, 51 Qinghai, 1 Yunnan was investigated; collected. Almost all the qualitative traits including crude protein, fiber, starch, neutral detergent fiber, and acid detergent fiber exhibited significantly high variability (p≤0.0001) among the cultivars. The data were analyzed using Statistics 8.1. In this study, significantly high variation was observed between starch content and neutral detergent fiber (23.64% and 11.54%). However, the highest diversity is based on the magnitude of the coefficient of variation exhibited in crude protein (13.82%), starch (12.87%), and fiber (12.17%). There was a significantly positive correlation between fiber, acid detergent fiber, and neutral detergent fiber except for starch content with crude protein and fiber that exhibited a significant negative correlation (r= -0.38*** and r= -0.92***). A large genetic diversity was observed through cluster analysis among all the 208 barley accessions, distance coefficient ranging between 0.28 and 75.86. The histogram revealed that frequency distributions of 208 different genotypes of hulless barley crop with all five different characters, crude protein, fiber, starch, neutral detergent fiber, and acid detergent fiber, showed normal distribution. It is concluded that this hulless barley study showed genetic diversity among the accessions and confirmed genetic diversity in various traits used.

Soybean is an important global crop used for oil, food, and feed production. To increase yield and land-use efficiency, growers often plant soybean at a high density or use intercropping systems. Under these systems, soybeans frequently experience shade stress, which directly affects agronomic traits such as plant height. Although researchers have well documented the genetic basis of plant height under normal conditions, the loci responsible for height variation under shade stress remain largely unexplored. Therefore, we performed a restricted two-stage multi-locus multi-allele genome-wide association study (RTM-GWAS) using SNP linkage disequilibrium block (SNPLDB) markers to identify QTLs associated with soybean plant height under shade stress. We evaluated a natural population of 181 soybean accessions for plant height traits under both normal and shaded conditions across four environments for three years. Using the Soybean40K chip, we derived 11,463 SNPLDB markers and identified 42, 33, and 28 significant SNPLDBs associated with plant height, average internode length, and number of main-stem nodes, respectively. For each SNPLDB, we estimated haplotype (allele) effects and assembled QTL–allele matrices to summarize the population’s genetic composition. Four SNPLDB loci proved stable across multiple environments, exhibiting high −lg(p) values and explaining substantial phenotypic variation. Finally, we projected that 80 candidate genes resided within 180 kb of these stable loci, and we identified four strong candidate genes linked to plant height traits based on combined positional and functional evidence. These results clarify genetic factors that influence soybean height under shading and could aid development of high-yielding soybean varieties.

Quinoa (Chenopodium quinoa Willd.) stands out as a versatile cereal crop, celebrated for its exceptional nutritional content and medicinal properties, as well as a wide range of morphological and genomic variations. Despite numerous studies on the genetic diversity of quinoa germplasm, a comprehensive assessment remains insufficient. In contrast, research focusing on the DUS traits and molecular variation in the germplasm used in China is relatively limited. We thoroughly examined 170 quinoa accessions, focusing on 30 morphological characterizations based on DUS descriptors (referred to as DUS testing traits) and 23 simple sequence repeat (SSR) markers. The results indicated that all 30 DUS testing traits were polymorphic. In total, we detected 136 allelic variations across the 170 varieties, averaging 4.53 per trait. The average Shannon index (I) was 0.97, with values ranging from 0.09 to 1.67. Diversity was highest at T30 (Time of maturity) and lowest at T6 (Stem: color). Using the UPGMA (unweighted pair-group method with arithmetic means) method, the cultivars were classified into three distinct groups, a categorization further supported by principal component analysis. To streamline field identification and screening, 18 key traits were identified based on principal component scores. Furthermore, the genetic diversity of all materials was analyzed using 23 SSR markers. The analysis revealed an average of 11.185 observed alleles, 3.874 effective alleles, a Nei’s gene diversity index of 0.680, and a Shannon’s information index(I) of 1.547, highlighting the substantial genetic diversity within the population. Subsequent genetic structure and DAPC (Discriminant analysis of principal components) analysis divided the population into four subgroups, reflecting the cluster analysis results. Notably, a significant portion of total genetic variation (58.033%) existed among individuals, with 26.289% among subgroups. The analysis also showed a notable degree of gene flow variation, with an estimated Nm value of 0.701, underscoring the genetic diversity among the quinoa cultivars studied. The use of a comprehensive set of 23 SSR markers, alongside DUS traits, proved highly effective in accurately distinguishing the tested quinoa cultivars. This robust method provided valuable insights that could significantly contribute to conserving quinoa genetic resources and enhancing their use.