RNA-Seq analysis of transgenic tobacco overexpressing Brassica 3-hydroxy-3- methylglutaryl-CoA synthase

Abstract

3-Hydroxy-3-methylglutaryl-CoA synthase (HMGS) is the second enzyme in the mevalonate pathway. It catalyses the condensation of acetoacetyl-CoA and acetyl-CoA to form HMG-CoA. Brassica juncea HMGS1 was shown to be important in the MVA pathway. When mutants of recombinant B. juncea HMGS1 (BjHMGS1) were generated for in vitro enzyme assays, the S359A mutant had 10-fold higher activity. Transgenic tobacco overexpressing wild-type and mutant HMGS (S359A) showed induction of several downstream genes in seedlings, increasing sterol content, plant growth, pod size and seed production over the vector-transformed control. More interestingly, tobacco OE-S359A showed a better effect in improving growth and seed yield than OE-wtBjHMGS1. Despite the moderate sterol increases in tobacco HMGS-OEs, surprisingly this was accompanied by significant increases in growth and seed yield. To address this question more in detail, transcriptome analysis was carried out and results derived will be presented.