Identification and phylogenetic analysis of a novel starch synthase in maize

Abstract

Starch is an important reserve of carbon and energy inplants, providing the majority of calories in the human diet and animal feed. Its synthesis is orchestrated byseveral key enzymes, and the amount and structure of starch, affecting crop yield and quality, are determined mainly by starch synthase(SS) activity. Todate, five SSisoforms,includingSSI-IV and Granule Bound Starch Synthase(GBSS) have been identified and the irphysiological functions have been well characterized. Here, we report the identification of a new SSisoforminmaize, designated SSV. By searching sequenced genomes, SSV has been found in all green plants with conserved sequences and gene structures. Our phylogenetic analysis based on 780 base pairs has suggested that SSIV and SSV resulted fromagene duplicationevent, which may have occurred before the algae formation. Anexpression profile analysis of SSV inmaizehas indicated that Zm SSVis mainly transcri bedin the kernelandear leaf during the grainfilling stage,which is partly similar too ther SSi so forms. Therefore, itislikely that SSV may play an importan troleinstarchbio synthesis. Subsequent analysis of SSV functionmay facilitate under standing theme chanismofstarchgranules formation,number and structure.