优质稻‘黄华占’籽粒发育过程中代谢物差异分析

Analysis of Metabolite Differences in the Process of Grain Development of High-Quality Rice ’Huanghuazhan’

为探究代谢物质、尤其是营养物质在优质稻籽粒发育过程中的数量、种类及丰度变化。本研究以中国南方稻区推广面积最大的优质常规籼稻品种‘黄华占’为材料,选取花后8 d (乳熟期),15 d (蜡熟期)和30 d(完熟期)的籽粒和精米,进行广泛靶向代谢组分析。在籽粒发育过程中,大分子代谢物质淀粉和直链淀粉的含量呈上升趋势,而可溶性蛋白变化则相反;在小分子代谢物方面,本研究鉴定获得23类622个代谢物,在花后8和15 d的籽粒中发现281个差异的代谢物,其中脂质是上升数量最多的物质。在花后15和30 d籽粒的差异物质最少,仅有61个,主要是黄酮物质且其丰度显著下降;在花后30 d籽粒和精米中,发现387个显著差异的代谢物,主要是氨基酸、有机酸和核苷酸及衍生物并发现135个代谢物完全流失。总之,在乳熟期和腊熟期代谢最为活跃,无论是淀粉和蛋白质,还是氨基酸、脂质、黄酮、维生素和萜类等小分子,均在此时期合成和积累。而在完熟期,仅黄酮的丰度显著下降。成熟籽粒至精米过程中,人为因素导致94%差异代谢物显著下降,甚至完全流失。本研究为在代谢物水平探究水稻营养品质形成机理提供理论依据,并为实际生产过程中,水稻收获后人为因素影响营养品质提供了重要参考。

To explore the changes in the quantity, type and abundance of metabolites, especially nutrient metabolites, in the developing grain and milled rice of high-quality rice in South China, the grains milky grains(8 d,8 days after flowering), dough grains(15 d), mature grains(30 d) and milled rice of ’Huanghuazhan’, the largest plantation in southern China, were analyzed by a widely targeted metabolomics approach. The content of macromolecular metabolites(starch and amylose) showed an upward trend, while the changes of soluble protein were opposite during the process from grain to milled rice. In terms of small molecule metabolites, 23 categories of 622 metabolites were identified in this study, and 281 metabolites with significant differences were found in grains at 8 and 15 days of grain filling, among which lipids were the substances with the largest increase. There were only 61 different substances between 15 and 30 DAF, mainly flavonoids, and their abundance decreased significantly. There were 22 categories of 387 metabolites, including amino acids and derivatives, organic acids and derivatives, nucleotides and derivatives, and 135 metabolites were completely lost during grain(30 d) to milled rice process. In conclusion, starch and protein, as well as amino acids, lipids, flavonoids, vitamins and terpenes were synthesized and accumulated during milky and dough grains. Only the abundance of flavonoids decreased significantly at the later stage of grain-filling. Human factors cause 94% of the differential metabolites to drop significantly or even completely lose during mature grain to milled rice process. This study provides a theoretical basis for exploring the formation mechanism of rice nutritional quality at the metabolite level, and provides an important reference for human factors affecting the nutritional quality of rice in the actual production process.