Poster: Seed Biology

Abs # 554: Endosperm-specific expression of a microbial sucrose phosphorylase transgene in maize altered carbohydrate metabolism in kernels.

Presenter:	Deikman, Jill , jill.deikman@monsanto.com
Authors	Deikman, Jill  (A)   Weldon, Marcia L. (A)   Jones, Don  (A)   Heredia, Oscar  (A)   Thompson, Rebecca  (A)   Miller, Philip W. (A)
Affiliations:	(A): Monsanto Company

The first step of starch biosynthesis in maize kernels is hydrolysis of sucrose by sucrose synthase to UDP-glucose and fructose, followed by conversion of UDP-glucose to glucose-1-phosphate by UDPglucose pyrophosphorylase. The microbial sucrose phosphorylase enzyme catalyzes breakdown of sucrose to form fructose and glucose 1-phosphate directly. A construct to express a transgene encoding a microbial sucrose phosphorylase in endosperm tissue was introduced into maize to examine the effect of the transgene on carbohydrate metabolism. Transformed lines expressing a single copy of the transgene were selected, along with negative segregants. Transgenic plants were crossed to a tester, and hybrid kernels were harvested at several time points during the fill period. Sucrose, glucose, fructose and starch concentrations in the kernels were measured. Significant differences in levels of these metabolites were observed compared to the isogenic negative controls. Most notably, an increase in starch was seen in mature kernels.