背景回顾：The root:shoot ratio has long been known to be enhanced in plants under drought stress. 

主要发现：Here we discovered that osmotic stress enhances long-distance sucrose transport to increase the root:shoot ratio in an abscisic-acid-dependent manner. 

结果1-诱导表达：The Arabidopsis sucrose transporters SWEET11 and 12, key players in phloem loading, are rapidly phosphorylated upon drought and abscisic acid treatments. 

结果2-干旱/ABA-SnRK2-SWEET11/12磷酸化：The drought- and abscisic-acid-activated SnRK2 protein kinases phosphorylate the carboxy-terminal cytosolic regions of SWEET11 and 12. 

结果3-SWEET11/12磷酸化促进根生长：This phosphorylation enhances the oligomerization and sucrose transport activity of SWEETs, which results in elevated sucrose contents in roots and improved root growth under drought stress, leading to the enhanced root:shoot ratio of biomass and drought resistance. 

结果3-磷酸化SWEETs功能：Notably, the expression of phospho-mimic SWEETs led to improved root growth even under non-stressed conditions.

结论：The phosphorylation of sucrose transporters provides an explanation for the long-standing observation that drought stress enhances the root:shoot ratio in plants and suggests a strategy for engineering drought-resistant crops.

 摘 要 

长期以来，人们都知道植物在干旱条件下的根冠比是增强的。本文中，作者发现渗透胁迫增强了长距离的蔗糖转运，从而增加了植株的根冠比，并且该过程依赖于脱落酸ABA。拟南芥的蔗糖转运蛋白SWEET11和12是韧皮部装载的关键蛋白，这两个蛋白在干旱和ABA处理下会被快速磷酸化。干旱和ABA激活的SnRK2蛋白激酶磷酸化SWEET11和12的C端胞质区域。该磷酸化增强了SWEET蛋白的齐聚化和蔗糖转运活性，从而导致根中具有更高水平的蔗糖含量，增强了干旱胁迫条件下根的生长，从而增强了植物在生物量方面的根冠比和干旱胁迫抗性。有趣的是，磷酸化mimic SWEETs的表达甚至能够在非胁迫条件下，增强根的生长。蔗糖转运蛋白的磷酸化为长期观察到的干旱胁迫下植物根冠比的增强提供了一个合理的解释，并且为作物的干旱抗逆育种提供了一种可能。

 通讯作者 

** 赵 杨 **