Agro-morphological variability and genetic diversity in linseed (Linum usitatissimum L.) germplasm accessions with emphasis on flowering and maturity time

Assessment of genetic diversity and extent of trait variation among germplasm accessions facilitate the effective use of genetic resources for varietal development. In linseed (Linum usitatissimum L.), early maturity is desirable as it helps avoid several biotic and abiotic stress. In present study, genetic variability of 220 accessions of linseed was studied using 25 agro-morphological traits for 2 years, 2017-2018 and 2018-2019. Remarkable variability was observed for flowering, maturity and other economically important traits such as thousand seed weight, capsule number, seed, and capsule area. Based on 2-year evaluation data for flowering and maturity traits, a panel of 34 accessions was constructed to study genetic diversity using SSR markers. Total 89 alleles were amplified with a mean of 3.069 alleles per locus. Polymorphism information content value ranged from 0.20 to 0.66 with mean of 0.42. Clustering based on SSR data followed the flowering-maturity trait pattern to a large extent. Genetic population structure analysis showed two populations in similarity with the trait groups. Analysis of molecular variance revealed 16% variance among the populations. Shannon's diversity information index within population I and II were 0.67 and 0.78, respectively. Additionally, allelic variation in a putative floral homeotic gene encoding APETALA2 transcription factor was studied in two early and two late accessions by PCR amplification and sequencing. Total 12 SNPs were identified, of which six could distinguish early and late accessions. The genetic and genomic resources identified here are expected to aid in linseed genetic improvement programme targeted to specific traits, especially, early flowering and maturity.