Li Chengxiang, Zhang Bin, Chen Bin, Ji Lianghui, Yu Hao
Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 117543, Singapore.
Temasek Life Sciences Laboratory, National University of Singapore, Singapore, 117604, Singapore.
Nat Commun. 2018 Feb 8;9(1):571. doi: 10.1038/s41467-018-03013-5.
Seed development is dependent on nutrients, such as a source of carbon, supplied by the parent plant. It remains largely unknown how these nutrients are distributed to zygotic and maternal tissues to coordinate storage of reserve compounds and development of protective tissues like seed coat. Here we show that phosphorylation of TRANSPARENT TESTA GLABRA1 (TTG1) is regulated by SHAGGY-like kinases 11/12 (SK11/12) and that this mediates carbon flow to fatty acid synthesis and seed coat traits in Arabidopsis seeds. SK11/12 phosphorylate TTG1 at serine 215, thus preventing TTG1 interaction with TRANSPARENT TESTA2. This compromises recruitment of TTG1 to the GLABRA2 locus and downregulates GLABRA2 expression, which enhances biosynthesis of fatty acids in the embryo, but reduces production of mucilage and flavonoid pigments in the seed coat. Therefore, site-specific phosphorylation of TTG1 by SK11/SK12 regulates carbon partitioning between zygotic and maternal sinks in seeds.
种子发育依赖于母本植物提供的营养物质，如碳源。目前尚不清楚这些营养物质如何分配到合子组织和母体组织，以协调储备化合物的储存以及种皮等保护组织的发育。在此我们表明，类SHAGGY激酶11/12（SK11/12）调节透明种皮1（TTG1）的磷酸化，这介导了碳流向脂肪酸合成以及拟南芥种子的种皮性状。SK11/12在丝氨酸215处使TTG1磷酸化，从而阻止TTG1与透明种皮2相互作用。这损害了TTG1在GLABRA2位点的募集并下调GLABRA2表达，这增强了胚胎中脂肪酸的生物合成，但减少了种皮中黏液和类黄酮色素的产生。因此，SK11/SK12对TTG1的位点特异性磷酸化调节了种子中合子和母体库之间的碳分配。
