博文
New Phytologist：SWEET蛋白作用于水稻种子鼓粒
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SWEET11 and 15 as key players in seed filling in rice
First author: Jungil Yang; Affiliations: Heinrich-Heine University Duesseldorf (杜塞尔多夫海因里希·海涅大学): Duesseldorf, Germany
Corresponding author: Joon-Seob Eom
Despite the relevance of seed-filling mechanisms for crop yield, we still have only a rudimentary (初步的) understanding of the transport processes that supply the caryopsis (颖果) with sugars. We hypothesized that SWEET sucrose transporters (蔗糖转运蛋白) may play important roles in nutrient import pathways in the rice caryopsis. We used a combination of mRNA quantification, histochemical analyses (组织化学分析), translational promoter–reporter fusions and analysis of knockout mutants created by genomic editing to evaluate the contribution of SWEET transporters to seed filling. In rice caryopses, SWEET11 and 15 had the highest mRNA levels and proteins localized to four key sites: all regions of the nucellus (珠心) at early stages; the nucellar projection (珠心突起) close to the dorsal vein (背面的叶脉); the nucellar epidermis (珠心表皮) that surrounds the endosperm (胚乳); and the aleurone (糊粉层). ossweet11;15 double knockout lines accumulated starch (淀粉) in the pericarp (果皮), whereas caryopses did not contain a functional endosperm. Jointly, SWEET11 and 15 show all the hallmarks (特征) of being necessary for seed filling with sucrose efflux (蔗糖流) functions at the nucellar projection and a role in transfer across the nucellar epidermis/aleurone interface (交界面), delineating (描述) two major steps for apoplasmic seed filling, observations that are discussed in relation to observations made in rice and barley regarding the relative prevalence of these two potential import routes (渠道).
除了知道鼓粒机制与作物产量之间存在关联之外，我们对于颖果的糖供应转运进程还只是个初步的了解。作者推测蔗糖转运蛋白SWEET可能在水稻颖果的营养供给路径中扮演重要的作用。作者通过综合利用mRNA定量、组织化学分析和转启动子-报道基因融合蛋白及利用基因组编辑敲除目标基因获得突变体等方法评估SWEET转运蛋白对于鼓粒的贡献。在水稻的颖果中，SWEET11和SWEET15基因具有最高的mRNA水平，其蛋白定位于4个关键位置，分别是：早期遍布珠心；靠近背面叶脉的珠心突起部分；环绕胚乳的珠心表皮；以及糊粉层。ossweet11;15双突变体株系会在果皮中积累淀粉，而颖果中未形成具有功能的胚乳。另外，SWEET11和SWEET15蛋白对于鼓粒期中在珠心突起的蔗糖流功能是必需的，这两个蛋白还在珠心表皮和糊粉层的交界处祈祷转运作用，这两步恰是质外体种子填充的主要步骤。作者还讨论了关于水稻和大麦关于这两个潜在的运输渠道的相对优势。
通讯：Joon-Seob Eom (http://www.mpipz.mpg.de/4452305/members)
研究方向：叶肉到种子贮藏细胞的蔗糖途径；糖转运蛋白在病原体易感性中所起的作用。
doi: 10.1111/nph.15004
Journal: New Phytologist
First Published date: 02 February, 2018
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https://blog.sciencenet.cn/blog-3158122-1098481.html
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