SWEET genes responsible for sugar transport in plant: A review

Abstract

Sugars will eventually be exported transporter (SWEET) is a novel class of sugars transporter families which mainly mediate either sucrose or hexose translocation bidirectional across the cellular membranesfollowinga concentrating gradient with a passive diffusion patten. In higher plants, SWEET proteins commonly have seven transmembrane domains that form a pore in the membrane to allow the passage of sugars, containing two MtN3/Saliva domains. Phylogenetically, plant SWEETs are divided into four clades. SWEET transporters play important roles in diverse physiological and biochemical processes including phloem loading, plant hormone transportand vegetative growth. In this review, based on the current advance of the plant SWEET transporters, we summarized their discovery, structure characteristicsand biological functions, and pointed out current research problems. Finally,put forward several better future research directions and potential solutions for SWEET sugar transporters in plant from the following three aspects: 1) exploring the molecular mechanism of substrate recognition and selectivity of SWEET proteins; 2) mining and utilizing of key SWEET genes increasing crop yield and improving quality; 3) using gene editing technology and phosphorylation of SWEET transporters to engineer high-yielding and high-quality crops.

Keywords

• genetic engineering; sugar transport; sweet; structure characteristics; biological functions