Production of high-amylose maize lines using RNA interference in sbe2a

Abstract

To regulate the biosynthetic process of maize starch and produce high-amylose transgenic maize, RNA interference was used to inhibit the starch branching enzyme gene Sbe2. A construct with a 562 bp segment of Sbe2 (pRSBE2a) was cloned as inverted repeats. Highly efficient RNAi vector pRSBE2a was transferred to inbred maize line H99 by Agrobacterium tumefaciens mediated transformation. Two transgenic plants of the T₁ generation were obtained with a single or double T-DNA copy number, and the interference segments were observed in transgenic T₂ plants. The transcription of sbe2a and the activity of starch branching enzyme (SBE) were severely inhibited in transgenic plants, and SBE activity was decreased by up to 67.8%. The total starch content had no significant difference between the transgenic and control (wild type) plants, but the percentage of amylose was increased to approximately 66.8% versus the control. In conclusion, RNAi to silence endogenous gene sbe2a could produce high-amylose maize lines with a low T-DNA copy number, demonstrating that RNAi is an efficient method for the production of high-amylose maize lines.

Key words: Maize, high-amylose, RNA interference, starch branching enzyme gene sbe2a.