Virus-induced Silencing SBEIIa and SSIIa, Alone or Together, Increased the Amylose and Resistant Starch Contents in Spring Wheat

Foods rich in amylose and resistant starch (RS) have great potential to improve human health and lower the risk of noninfectious diseases. Common wheat (Triticum aestivumL.) is a major staple food crop with low RS content in the grains. The content of RS, preferentially derived from amylose, may be increased by suppressing amylopectin synthesis viasilencing the starch branching enzyme (SBE) II a or/and starch synthase (SS)IIa. In this study, SBEIIaand SSIIawere silenced separately and simultaneously using a barley stripe mosaic virus-virus-induced gene silencing (BSMV-VIGS) system. Compared with grains from control BSMV:00-inoculated spikes, grains from BSMV:SBEIIa-and BSMV:SSIIa-infected spikeshad fewer SBEIIa and SSIIa transcripts,together with increased amylose contents (18.62 and 24.48%, respectively) and RS contents (11.61 and 16.67%, respectively). Infection with BSMV:SBEIIa-SSIIa reduced SBEIIa and SSIIatranscript levels and increased the amylose and RS contents (32.02 and 22.33%, respectively). Thus, BSMV-VIGS is a useful tool for the rapid silencing of single or multiple starch synthase-related genes and BSMV shows great potential to study the functions of genes involved in starch biosynthesis or other processes/traits in developing grains.We showed that the SSIIagene plays an important role in the synthesis of amylose and RS and that the effects of simultaneously silencing SBEIIaand SSIIaon starch synthesis aregreater than those of single gene silencing. Our study lays the foundation for the molecular design-based breeding of high-amylose and high-RS wheat.© 2021 Friends Science Publishers