Abstract
Starch is an important reserve of carbon and energy in plants, providing the majority of calories in the human diet and animal feed. Its synthesis is orchestrated by several key enzymes, and the amount and structure of starch, affecting crop yield and quality, are determined mainly by starch synthase (SS) activity. To date, five SS isoforms, including SSI-IV and Granule Bound Starch Synthase (GBSS) have been identified and their physiological functions have been well characterized. Here, we report the identification of a new SS isoform in maize, 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 from a gene duplication event, which may have occurred before the algae formation. An expression profile analysis of SSV in maize has indicated that ZmSSV is mainly transcribed in the kernel and ear leaf during the grain filling stage, which is partly similar to other SS isoforms. Therefore, it is likely that SSV may play an important role in starch biosynthesis. Subsequent analysis of SSV function may facilitate understanding the mechanism of starch granules formation, number and structure.
Highlights
Starch, a polymer of glucose, is an important reserve of carbon and energy in plants (Zeeman et al, 2010)
Starch biosynthesis occurs in chloroplasts and Abbreviations: DAP, days after pollination; DP, degree of polymerization; Granule Bound Starch Synthase (GBSS), Granule Bound starch synthase; GS, glycogen synthases; SBP, starch biosynthesis pathway; SS, starch synthase
The amino acid sequence deduced from the open reading frame (ORF) contains 701 residues with a predicted molecular mass of about 78.6 kDa
Summary
A polymer of glucose, is an important reserve of carbon and energy in plants (Zeeman et al, 2010) In photosynthetic tissues, it is stored as a transient form in chloroplasts during daylight hours and is mobilized at night to provide carbon skeletons and energy for metabolism. Starch in plant storage tissues is the major source of calories in the human diet and animal feed. It is an economical, biodegradable and renewable industrial raw material, widely used in papermaking and first-generation bioethanol production (Smith, 2008; Zeeman et al, 2010). Starch biosynthesis occurs in chloroplasts and Abbreviations: DAP, days after pollination; DP, degree of polymerization; GBSS, Granule Bound starch synthase; GS, glycogen synthases; SBP, starch biosynthesis pathway; SS, starch synthase
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
