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

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.

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.

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.