Natural variations in Os gamma TMT contribute to diversity of the alpha-tocopherol content in rice

Abstract

Tocopherols and tocotrienols, collectively known as tocochromanols, are lipid-soluble molecules that belong to the group of vitamin E compounds. Among them, alpha-tocopherol (alpha Icurrency sign) is one of the antioxidants with diverse functions and benefits for humans and animals. Thus, understanding the genetic basis of these traits would be valuable to improve nutritional quality by breeding in rice. Genome-wide association study (GWAS) has emerged as a powerful strategy for identifying genes or quantitative trait loci (QTL) underlying complex traits in plants. To discover the genes or QTLs underlying the naturally occurring variations of alpha Icurrency sign content in rice, we performed GWAS using 1.44 million high-quality single-nucleotide polymorphisms acquired from re-sequencing of 137 accessions from a diverse rice core collection. Thirteen candidate genes were found across 2-year phenotypic data, among which gamma-tocopherol methyltransferase (Os gamma TMT) was identified as the major factor responsible for the alpha Icurrency sign content among rice accessions. Nucleotide variations in the coding region of Os gamma TMT were significantly associated with the alpha Icurrency sign content variations, while nucleotide polymorphisms in the promoter region of Os gamma TMT also could partly demonstrate the correlation with alpha Icurrency sign content variations, according to our RNA expression analyses. This study provides useful information for genetic factors underlying alpha Icurrency sign content variations in rice, which will significantly contribute the research on alpha Icurrency sign biosynthesis mechanisms and alpha Icurrency sign improvement of rice.