Sucrose Efflux Mediated by SWEET Proteins as a Key Step for Phloem Transport

That Sweet Sensation Photosynthesis in the leaf generates sucrose that must be transported via the phloem to other parts of the plant in order, for example, to be incorporated into harvestable produce. Studying Arabidopsis and rice, Chen et al. (p. 207, published online 8 December; see the Perspective by Braun ) identified the SWEET family of sucrose efflux transporters that are responsible for carrying sucrose out of the leaf cells. When the transporters were disabled, sucrose accumulated in the leaves. Functioning properly, the SWEET transporters carry sucrose across the plasma membrane and other transporters move it further into the phloem.