Enhancing the expression of starch synthase class IV results in increased levels of both transitory and long-term storage starch

Starch is an important renewable raw material with an increasing number of applications. Several attempts have been made to obtain plants that produce modified versions of starch or higher starch yield. Most of the approaches designed to increase the levels of starch have focused on the increment of the amount of ADP-glucose or ATP available for starch biosynthesis. In this work, we show that the overexpression of starch synthase class IV (SSIV) increases the levels of starch accumulated in the leaves of Arabidopsis by 30%-40%. In addition, SSIV-overexpressing lines display a higher rate of growth. The increase in starch content as a consequence of enhanced SSIV expression is also observed in long-term storage starch organs such as potato tubers. Overexpression of SSIV in potato leads to increased tuber starch content on a dry weight basis and to increased yield of starch production in terms of tons of starch/hectare. These results identify SSIV as one of the regulatory steps involved in the control of the amount of starch accumulated in plastids. © 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

This research was partially supported by grants BIO2009-07040, BIO2007-63915 and PET2008-0106 from the Comisio´n Interministerial de Ciencia y Tecnología and Fondo Europeo de Desarrollo Regional (Spain), Iden Biotechnology S.L., and by grant P09-CVI-4704 from Junta de Andalucı´a. P.R. was supported by FPU grant from Spanish Ministry of Education. M.O. was partly supported by grant No. 2 ⁄ 0200 ⁄ 10 from the Grant Academy VEGA.

Peer Reviewed