Impaired phloem loading in zmsweet13a,b,c sucrose transporter triple knock-out mutants in Zea mays
Impaired phloem loading in zmsweet13a,b,c sucrose transporter triple knock-out mutants in Zea mays
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DOI：
10.1111/nph.15021
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发表时间：
2018-04-01
期刊：
影响因子：
9.4
通讯作者：
Sosso, Davide
中科院分区：
文献类型：
--
作者：
Bezrutczyk, Margaret;Hartwig, Thomas;Sosso, Davide
作物产量取决于蔗糖从叶片到种子的有效分配。在拟南芥中，韧皮部负载由SWEET蔗糖流出物和随后的SUT 1/SUC 2蔗糖/H+共转运体的摄取的组合介导。ZmSUT 1对玉米中的碳分配是必不可少的，但对质外韧皮部装载和从易位路径泄漏的蔗糖的回收的相对贡献尚不清楚。在这里，我们分析了SWEET对玉米韧皮部负载的贡献。我们确定了三个叶片表达的SWEET蔗糖转运蛋白作为玉米质外质韧皮部装载的关键组分。ZmSWEET 13旁系同源物（a、B、c）是叶脉管系统中最高表达的基因之一。基因组编辑的三重敲除突变体严重发育不良。突变体的光合作用受损，叶片积累高水平的可溶性糖和淀粉。RNA-seq揭示了与光合作用和碳水化合物代谢相关的基因的转录失调。全基因组关联分析（GWAS）表明，ZmSWEET 13 s的变异与农艺性状相关，尤其是开花时间和叶角。本研究为3个ZmSWEET 13与ZmSUT 1在玉米韧皮部装载中的协同作用提供了支持。
Crop yield depends on efficient allocation of sucrose from leaves to seeds. In Arabidopsis, phloem loading is mediated by a combination of SWEET sucrose effluxers and subsequent uptake by SUT1/SUC2 sucrose/H+ symporters. ZmSUT1 is essential for carbon allocation in maize, but the relative contribution to apoplasmic phloem loading and retrieval of sucrose leaking from the translocation path is not known. Here we analysed the contribution of SWEETs to phloem loading in maize. We identified three leaf-expressed SWEET sucrose transporters as key components of apoplasmic phloem loading in Zea mays L. ZmSWEET13 paralogues (a, b, c) are among the most highly expressed genes in the leaf vasculature. Genome-edited triple knock-out mutants were severely stunted. Photosynthesis of mutants was impaired and leaves accumulated high levels of soluble sugars and starch. RNA-seq revealed profound transcriptional deregulation of genes associated with photosynthesis and carbohydrate metabolism. Genome-wide association study (GWAS) analyses may indicate that variability in ZmSWEET13s correlates with agronomical traits, especifically flowering time and leaf angle. This work provides support for cooperation of three ZmSWEET13s with ZmSUT1 in phloem loading in Z.mays.