Sucrose Transport in Higher Plants: From Source to Sink

Abstract

Sucrose transport in plants has been as area of intense interest for many years, particularly following the cloning of the first sucrose/proton symporter, or sucrose transporter, from spinach more than 15 years ago. Much debate and research has focused on phloem loading, particularly the issue of apoplasmic versus symplasmic pathways of loading and in the apoplasmic loaders, on the location of the sucrose transporter protein and mRNA. This chapter focuses on pointing out the remaining unanswered questions in phloem loading and sucrose transport in general rather than extensively reviewing the literature. We discuss in more detail the long-distance transport pathway from source to sink and post-phloem unloading in sink tissue such as dicot seed, cereal grain, sink leaves, roots and tubers.