The sucrose transporter <i>TaSWEET11</i> is critical for grain filling and yield potential in wheat (<i>Triticum aestivum</i> L.)

Abstract

Grain filling, a crucial process that determines grain weight, is regulated by the efficiency of sugar transport to the caryopsis. However, the regulation of sugar transport during this process in wheat remains largely unknown. In this study, we conducted genetic and transcriptomic analyses to investigate the role of TaSWEET11 in grain filling and its contribution to grain weight. TaSWEET11 encodes a membrane-localized protein and is primarily expressed in developing grains, specifically in the vascular bundle and nucellar projection. Knocking out TaSWEET11 disrupted starch synthesis in developing grains, resulting in shrunken and empty-pericarp grains. Further investigation revealed that TaSWEET11 is involved in sucrose transport, as knockout lines exhibited significantly reduced sucrose content. Transcriptomic analysis showed significant downregulation of genes related to starch synthesis and sucrose metabolism in knockout lines, shedding light on the mechanism behind grain shrinkage. Notably, overexpressing TaSWEET11 had a positive impact on effective tiller number, spike length, grain number per spike, and ultimately grain yield in CB037. In addition, TaSWEET11, as a key factor for grain filling, underwent strong selection during wheat domestication and breeding programs. Overall, these findings highlight the crucial role of TaSWEET11 in sucrose transport during grain filling and suggest its potential as a target for increasing wheat yield.