胡萝卜素 z-bo 2020-10-30 368

　　Recently, Wu Yongrui's research group, a researcher at the Center for Excellence in Molecular Plant Sciences of the Chinese Academy of Sciences, published a research paper entitled Carotenoids modulate kernel texture in maize by infuencing amyloplast envelope integrity on Nature Communications. This study was the first to clone from a natural population the main QTL that controls the formation of corn hard/mey endosperm-Ven1 (Vitreous endosperm 1), and found that the allelic variation of this gene can regulate the polarity and non-polarity of carotenoids in corn endosperm. The content of sexual components. The increase of non-polar carotene delays the degradation of amyloid membranes, hinders the interaction of protein bodies and starch granules, thereby affecting the formation of hard endosperm.

　　Corn kernel hard/mey endosperm is a pair of important agronomic traits that affect the harvest, storage, transportation and food processing of corn. The formation of hard endosperm depends on the close interaction between protein bodies (storing gliadin) and amyloid bodies. During the development of corn endosperm, the outer endosperm region has dense protein bodies and small starch grains; the central region has sparse protein bodies and large starch grains. When the grain is mature and dehydrated, the protein bodies in the peripheral area of the endosperm and other contents in the cell (cytoplasm, organelle, cytoskeleton, etc.) are intertwined to form a proteinaceous matrix, which tightly wraps the starch grains to form a dense hard Endosperm; due to the lack of protein bodies in the central region of the endosperm, the starch grains are completely exposed, forming a loose powdery endosperm. Maize endosperm durum phenotype has abundant variation in natural populations, from almost completely dull to completely dull materials. However, the academic community lacks the understanding of QTLs and molecular mechanisms that control its formation. Carotenoids are mainly concentrated in hard endosperm, and their composition and content determine the color of most corn varieties (variation from white to orange-red; purple corn is caused by the accumulation of anthocyanins in the aleurone layer). Although the carotenoid content has more variation in natural populations, the excellent allelic variation that can be used for vitamin A biofortification is less. Grain color and hard powder quality are obviously subject to artificial selection in the breeding process, but the internal connection between the two is not yet clear in the academic circles.

　　Researchers used ordinary hard corn inbred line W64A and silty corn inbred line A619 to construct hard and silty near-isogenic lines NILW64A and NILA619 under the background of A619 through 8 consecutive backcrossing. Through BSA sequencing, fine mapping and RNAi genetic verification, the main QTL that affects the formation of hard endosperm was cloned-Ven1. The gene encoding β-carotene hydroxylase 3 (HYD3) is highly expressed in endosperm starch cells, and the protein is located inside the amyloid membrane. Ven1 has fragment deletion and low expression in NILA619, which causes β-carotene to not be hydroxylated into downstream polar carotene, which increases the content of other non-polar carotene upstream. Thereby changing the physicochemical properties of the starch body membrane. The amyloid membrane (containing starch granules) of NILA619 has enhanced stability and irregular expansion, and its degradation is delayed during the dehydration of endosperm cells, which hinders the interaction between protein bodies and starch granules and the formation of protein matrix grids. When the grain matures, a powdery endosperm is formed. On the contrary, the hard near-isogenic line NILW64A has high expression of Ven1, reduced non-polar carotenoid content, regular amyloid membrane morphology and easy degradation, which is conducive to the concentration of protein bodies and cytoplasm on the surface of starch grains to form a dense protein matrix The grid surrounds the structure, which is an important basis for the formation of hard endosperm. In order to prove that excessive accumulation of non-polar carotene is the cause of A619's silty phenotype, the researchers performed large-scale EMS mutagenesis on A619 and obtained multiple mutant materials with inhibited upstream carotenoid synthesis pathways. The common features are From the powdery endosperm to the hard endosperm, it was named the suppressors of Ven1 (Ven1A619, Ves). Through GWAS analysis, it was found that there are multiple Ven1 modifiers in the natural population, that is, hard endosperm is formed without changing the carotene composition. The study revealed a new molecular genetic mechanism that carotenoids affect the formation of hard endosperm by affecting the stability of amyloid membranes, which is conducive to the cultivation of high-carotene hard corn varieties.

　　Molecular Plant Excellence Center associate researcher Wang Haihai and postdoctoral fellow Huang Yongcai are the co-first authors of the paper, and Wu Yongrui is the corresponding author of the paper. Doctoral students Xiao Qiao and Huang Xing, postdoctoral fellows Li Changsheng and Xiang Xiaoli, assistant researcher Wang Qiong, master student Zhu Yidong, associate researcher Wang Jiechen, public technology service center teacher Gao Xiaoyan, associate professor Wang Wenqin of Shanghai Jiaotong University, and Fellow of the University of Arizona Brian A. Larkins participated in the research. The research work is supported by the Ministry of Science and Technology, the National Natural Science Foundation of China, and the Strategic Leading Science and Technology Project of the Chinese Academy of Sciences.