Molecular cloning and functional characterization of a new Sucrose Transporter in hexaploid wheat (Triticum aestivum L.)

Abstract

Current bioethanol production is predominantly based on starch from cereal crops such as corn and wheat which leads to increased competition for such crops between the food, feed and bioethanol industries. Thus, enhancing the sustainability of the bioethanol industry, at least in the short term, requires increased starch yield per seed or per unit area. Starch content of wheat grains is partly determined by sucrose transport efficiency from the source (the leaf) to the sink organ (the grain) which is partly mediated by sucrose transporter (SUT) proteins. Only one functional SUT (TaSUT1) gene of wheat is known to date. Using molecular gene cloning approaches, this thesis project identified the three homeologues of a new SUT (TaSUT2) gene from hexaploid wheat and demonstrated their functionality as sucrose transporters through heterologous expression in mutant yeast. Characterization of the spatio-temporal expression of TaSUT2 suggested its role in phloem loading, unloading and sucrose retrieval.