Key message

Two BjuGα proteins exhibit conserved GTP-binding and GTP-hydrolysis activities, and function in maintaining overall plant architecture and controlling multiple yield-related traits in the oilseed Brassica juncea.

Abstract

Heterotrimeric G-protein (Gα, Gβ and Gγ) are key signal transducers, well characterized in model plants Arabidopsis and rice. However, our knowledge about the roles played by G-proteins in regulating various growth and developmental traits in polyploid crops, having a complex G-protein signalling network, is quite sparse. In the present study, two Gα encoding genes (BjuA.Gα1 and BjuB.Gα1) were isolated from the allotetraploid Brassica juncea, a globally cultivated oilseed crop of the Brassicaceae family. BjuGα1 genes share a close evolutionary relationship, and the encoded proteins exhibit highly conserved G-protein activities while showing expression differentiation, wherein BjuA.Gα1 was the highly abundant transcript during plant growth and developmental stages. RNAi based suppression of BjuGα1 displayed compromised effects on most of the tested vegetative and reproductive parameters, particularly plant height (32–58%), flower and siliques dimensions, and seed weight (11–13%). Further, over-expression of a constitutively active Gα, lacking the GTPase activity, produced plants with increased height, organ size and seed weight (7–25%), without altering seed quality traits like fatty acid composition, glucosinolates, oil and protein contents. Our study demonstrates that BjuGα1 proteins control overall plant architecture and multiple yield-related traits in the oilseed B. juncea, suggesting that BjuGα1 could be a promising target for crop improvement.

中文翻译：

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杂三聚体 Gα 亚基调节油籽芥菜中的植物结构、器官大小和种子重量。

关键信息

两种 BjuGα 蛋白表现出保守的 GTP 结合和 GTP 水解活性，并在油菜芥菜中维持整体植物结构和控制多种产量相关性状。

抽象的

异三聚体 G 蛋白（Gα、Gβ 和 Gγ）是关键的信号转导子，在模式植物拟南芥和水稻中得到了很好的表征。然而，我们对 G 蛋白在调节具有复杂 G 蛋白信号网络的多倍体作物的各种生长和发育性状中所起的作用的了解非常少。在本研究中，两个 Gα 编码基因（BjuA.Gα1和BjuB.Gα1 ）从十字花科全球栽培的油料作物异源四倍体芥菜中分离得到。BjuGα1基因具有密切的进化关系，编码的蛋白质在表达分化的同时表现出高度保守的 G 蛋白活性，其中BjuA.Gα1是植物生长发育阶段高度丰富的转录物。基于 RNAi 的BjuGα1抑制对大多数测试的营养和生殖参数显示出影响，特别是植物高度 (32-58%)、花和长角果尺寸以及种子重量 (11-13%)。此外，缺乏 GTPase 活性的组成型活性 Gα 的过度表达，产生的植物具有增加的高度、器官大小和种子重量（7-25%），而不会改变种子质量性状，如脂肪酸组成、硫代葡萄糖苷、油和蛋白质含量. 我们的研究表明，BjuGα1 蛋白控制油籽芥菜中的整体植物结构和多种产量相关性状，表明BjuGα1可能是作物改良的一个有希望的目标。