Characterization of phenotypic and genetic diversity in sodium azide-induced mutant populations in oat (Avena sativa).

BACKGROUND: Chemical mutagenesis coupled with molecular marker analysis is an efficient strategy for accelerating crop improvement and creating crop genetic diversity, yet optimized protocols and comprehensive evaluations chemical mutagenesis-assisted forage oats traits improvement and breeding understudied. This study aimed to assess sodium azide (SA)-induced mutagenesis in two oat varieties (Everleaf and 709) by characterizing phenotypic and molecular variations, identifying tissue-specific mutation patterns, and establishing efficient treatment parameters for breeding. RESULTS: SA treatment at > 10 mmol·L⁻1 caused severe germination inhibition (lethality > 60%) but maximized phenotypic variation (CV up to 90.80% for panicle traits). By phenotypic screening, out of 767 (M2-M3) mutants, a total of six categories of mutant phenotypes were identified: leaf traits were most frequently altered (1.02%), followed by seeds (0.39%). M2 mutation frequencies reached 17.9-23.73%. SSR markers revealed high polymorphism (60-100% polymorphic sites, PIC 0.27-0.80), amplifying 3-9 alleles/locus. Multivariate analyses (PCA, UPGMA, and STRUCTURE) grouped 293 mutants into four genetically distinct clusters, confirming genome-wide diversity. CONCLUSIONS: SA induces extensive and diverse heritable phenotypic and molecular variations in oats, with mutation spectra showing tissue-specific trends. The mutant libraries and polymorphic SSR markers developed provide a valuable resource for oat breeding and functional genomics. This work establishes a protocol for SA mutagenesis in oats and delivers mutant germplasm with broad applicability in trait improvement and genetic research.