Development of functional markers for high α-tocopherol content in Indian mustard [Brassica juncea (L.) Czern. and Coss] employing genetic and molecular analysis of VTE4 gene

Tocopherol (vitamin E) is considered an important vitamin carrying antioxidant properties. It plays a vital role in maintaining the quality and stability of oil in Brassica species. Molecular mechanisms of tocopherol content have been studied in Brassicas; however, it is untapped in Indian mustard (Brassica juncea). In the experiment, the expression profile and sequence variation of the candidate gene VTE4 controlling α-tocopherol content (ATC) were studied between two diverse parents (RLC-3 and NPJ-203) of B. juncea. The VTE4 gene expression in different tissues was almost double in NPJ-203 (high ATC genotype) as compared to RLC-3 (low ATC genotype). Moreover, sequence analysis of VTE4 in NPJ-203 and RLC-3 revealed the presence of two SNPs in the 6th exon, resulting in a shorter coding sequence (CDS) in RLC-3 (996 bp) as compared to NPJ-203 (1044 bp). Using these SNPs, an allele-specific marker was developed and validated in the F3 population. The single marker analysis revealed that the marker was significantly linked to the tocopherol content, contributing 16.46% to the total phenotypic variance. Thus, the study suggested that VTE4 is the major gene contributing to the tocopherol content, and the developed marker can be effectively used in marker-assisted breeding to improve tocopherol content in B. juncea.