Analysis of γ-Tocopherol methyl transferase3 promoter activity and study of methylation patterns of the promoter and its gene body.
Soybeans are known for its good source of protein (40%), oil (20%) and also serve as a source of nutraceutical compounds including tocopherols (toc). To know the molecular basis of differential α-toc accumulation in two contrasting soybean genotypes: DS74 (low α-toc - 1.36 μg/g and total-toc -29.72 μg/g) and Bragg (high α-toc - 10.48 μg/g and total-toc 178.91 μg/g), the analysis of γ-TMT3 promoter activity and its methylation patterns were carried out. The sequencing results revealed nucleotide variation between Bragg:γ-TMT3-P and DS74:γ-TMT3-P, however none of the variations were found in core-promoter region or in cis-elements. The histochemical GUS assay revealed higher promoter activity of Bragg:γ-TMT3-P than that of DS74:γ-TMT3-P and correlated with significantly higher and lower (P < 0.05) expression of γ-TMT3 gene respectively. To know the molecular basis of differential accumulation of α-toc in these contrasting soybean genotypes, the DNA methylation pattern of γ-TMT3 gene body and its promoter was studied in both varieties. The results showed higher percentage (62.5%) of methylation in DS74:γ-TMT3-P than in Bragg:γ-TMT3-P (50%). Out of all the methylation sites in the promoter region, one of methylation site was found at CAAT box (-190 bp) of DS74:γ-TMT3-P. Further gene body methylation patterns revealed lowest % (40%) of CG methylation in DS74:γ-TMT3 gene as compared to Bragg:γ-TMT3 (64.2%). Thus our study revealed that, expression of γ-TMT3 gene was influenced by its promoter activity and methylation patterns in cis-elements of γ-TMT3 promoter and gene body. This study will help us to understand the possible role of methylation and promoter activity in determining the α-toc content in soybean seeds.
['Kumari|Khushboo|K|', 'Rai|Monika Prakash|MP|', 'Bansal|Navita|N|', 'Rama Prashat|G|G|', 'Kumari|Sweta|S|', 'Krishnan|Veda|V|', 'Srivathsa|Rohini|R|', 'Dahuja|Anil|A|', 'Sachdev|Archana|A|', 'Praveen|Shelly|S|', 'Vinutha|T|T|']
D018506:Gene Expression Regulation, Plant D011401:Promoter Regions, Genetic D013025:Soybeans D024505:Tocopherols D024502:alpha-Tocopherol D024504:gamma-Tocopherol
Methylation Promoter Gene body methylation Gene expression Tocopherol biosynthesis cis-regulatory elements α-tocopherol