Xi Min, Li Zhong, Liang Shuang, Xu Youzun, Zhou Yongjin, Tu Debao, Sun Xueyuan, Yang Linsheng
Rice Research Institute, Anhui Academy of Agricultural Sciences, Anhui, Hefei, 230031, China.
BMC Plant Biol. 2025 Mar 19;25(1):356. doi: 10.1186/s12870-025-06368-2.
Grain protein is a critical quality attribute of rice that influences consumer preferences. However, the spatial variation in protein accumulation within a rice panicle remains poorly understood. This study investigated the dynamics of protein accumulation, including protein components and protein synthesis-related enzymes and genes, among grains located at the top, middle, and bottom primary rachises of a rice panicle during the grain filling. The results revealed significant variations in protein compositions across different rachis positions. The contents of albumin, globulin, prolamin, glutelin, and total protein contents exhibited fluctuations during grain filling. Notably, the grain position had a significant effect on glutelin content, with grains at the bottom primary rachis consistently having higher glutelin level than those at the top and middle rachises, except 17 days after flowering (DAF). A similar trend was observed for total protein content. Grains at the bottom rachis demonstrated dominance in the rate of protein accumulation, initiating rapid accumulation 2.0 d later and 2.2 d earlier than grains at the top and middle rachises, respectively. Furthermore, the duration of active protein accumulation was 1.9 d and 3.4 d shorter for grains at the bottom rachis compared to those at the top and middle rachises, respectively. This phenomenon was attributed to alterations in enzymatic activities. Specifically, the activities of glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate pyruvate transaminase (GPT), and glutamic oxalo-acetic transaminase (GOT) in grains located at the basal rachis exhibited a marked increase from 8 DAF to 17 DAF. These activities were significantly elevated compared to those observed in grains at the top and middle rachis, although they experienced a subsequent sharp decline. The glutelin content and enzymatic activities demonstrated a strong correlation, either positive or negative, at 11 DAF and 20 DAF. These findings suggest that the positional changes of grain protein were closely associated with nitrogen assimilation and glutelin accumulation during the rice grain filling process.
谷蛋白是影响消费者偏好的水稻关键品质属性。然而，水稻穗内蛋白质积累的空间变异仍知之甚少。本研究调查了水稻灌浆期穗部顶部、中部和底部一次枝梗上籽粒的蛋白质积累动态，包括蛋白质组分以及与蛋白质合成相关的酶和基因。结果显示，不同枝梗位置的蛋白质组成存在显著差异。在灌浆过程中，清蛋白、球蛋白、醇溶蛋白、谷蛋白含量及总蛋白含量均有波动。值得注意的是，籽粒位置对谷蛋白含量有显著影响，除开花后17天外，底部一次枝梗上的籽粒谷蛋白水平始终高于顶部和中部枝梗上的籽粒。总蛋白含量也呈现类似趋势。底部枝梗上的籽粒在蛋白质积累速率上占优势，分别比顶部和中部枝梗上的籽粒早2.0天和2.2天开始快速积累。此外，底部枝梗上籽粒的活跃蛋白质积累持续时间分别比顶部和中部枝梗上的籽粒短1.9天和3.4天。这种现象归因于酶活性的变化。具体而言，基部枝梗上籽粒中的谷氨酰胺合成酶（GS）、谷氨酸合酶（GOGAT）、谷丙转氨酶（GPT）和谷草转氨酶（GOT）的活性在开花后8天至17天显著增加。与顶部和中部枝梗上的籽粒相比，这些活性显著升高，尽管随后急剧下降。在开花后11天和20天，谷蛋白含量与酶活性呈显著正相关或负相关。这些发现表明，水稻灌浆过程中籽粒蛋白质的位置变化与氮素同化和谷蛋白积累密切相关。
