SULTR3s Function in Chloroplast Sulfate Uptake and Affect ABA Biosynthesis and the Stress Response
SULTR3s Function in Chloroplast Sulfate Uptake and Affect ABA Biosynthesis and the Stress Response
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SULTR3s 在叶绿体硫酸盐吸收中发挥作用并影响 ABA 生物合成和应激反应
DOI：
10.1104/pp.18.01439
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发表时间：
2019-05-01
期刊：
影响因子：
7.4
通讯作者：
Xiang, Cheng-Bin
中科院分区：
文献类型：
--
作者：
Chen, Zhen;Zhao, Ping-Xia;Xiang, Cheng-Bin
植物是全球硫磺循环中的主要减硫剂。硫酸盐是土壤中主要的天然硫源，被植物根吸收并运输到质体中，在那里被还原并同化为半胱氨酸，进行进一步的代谢过程。尽管硫酸盐很重要，但人们对硫酸盐是如何运输到质体中的知之甚少。我们以前利用单个拟南芥(Arabiopsis Thaliana)基因突变体证明了硫酸盐转运蛋白(SULTR)亚家族3的每个成员都能够通过叶绿体被膜运输硫酸盐。为了解决SULTR3的功能，我们构建了一个SULTR3五元组突变体，完全敲除了该亚家族的所有五个成员。在这里，我们报告了SULTR3亚家族的所有成员都显示出叶绿体膜的定位。与野生型相比，五重突变体的叶绿体对硫酸盐的吸收减少了50%以上。因此，半胱氨酸和脱落酸(ABA)含量分别降至接近野生型水平的67%和20%，且硫酸盐、半胱氨酸和ABA含量之间存在很强的正相关关系。苏特罗3五重突变体表现出明显的生长迟缓，玫瑰花序较小，根较短。该突变株的种子萌发对外源ABA和盐胁迫敏感，但硫化物补充剂能挽救种子萌发。此外，硫酸盐诱导的气孔关闭在五重突变体中被取消，强烈表明叶绿体硫酸盐是气孔关闭所必需的。我们的遗传分析明确表明，硫酸盐转运体亚家族3负责超过一半的叶绿体硫酸盐吸收，并影响下游硫酸盐的同化和ABA的生物合成。
Plants are major sulfur reducers in the global sulfur cycle. Sulfate, the major natural sulfur source in soil, is absorbed by plant roots and transported into plastids, where it is reduced and assimilated into Cys for further metabolic processes. Despite its importance, how sulfate is transported into plastids is poorly understood. We previously demonstrated using single Arabidopsis (Arabidopsis thaliana) genetic mutants that each member of the sulfate transporter (SULTR) subfamily 3 was able to transport sulfate across the chloroplast envelope membrane. To resolve the function of SULTR3s, we constructed a sultr3 quintuple mutant completely knocking out all five members of the subfamily. Here we report that all members of the SULTR3 subfamily show chloroplast membrane localization. Sulfate uptake by chloroplasts of the quintuple mutant is reduced by more than 50% compared with the wild type. Consequently, Cys and abscisic acid (ABA) content are reduced to similar to 67 and similar to 20% of the wild-type level, respectively, and strong positive correlations are found among sulfate, Cys, and ABA content. The sultr3 quintuple mutant shows obvious growth retardation with smaller rosettes and shorter roots. Seed germination of the sultr3 quintuple mutant is hypersensitive to exogenous ABA and salt stress, but is rescued by sulfide supplementation. Furthermore, sulfate-induced stomatal closure is abolished in the quintuple mutant, strongly suggesting that chloroplast sulfate is required for stomatal closure. Our genetic analyses unequivocally demonstrate that sulfate transporter subfamily 3 is responsible for more than half of the chloroplast sulfate uptake and influences downstream sulfate assimilation and ABA biosynthesis.