Heterotrimeric G proteins are important transducers of receptor signaling, functioning in plants with CLAVATA receptors in controlling shoot meristem size and with pathogen-associated molecular pattern receptors in basal immunity. However, whether specific members of the heterotrimeric complex potentiate cross-talk between development and defense, and the extent to which these functions are conserved across species, have not yet been addressed. Here we used CRISPR/Cas9 to knock out the maize G protein β subunit gene (Gβ) and found that the mutants are lethal, differing from those in Arabidopsis, in which homologous mutants have normal growth and fertility. We show that lethality is caused not by a specific developmental arrest, but by autoimmunity. We used a genetic diversity screen to suppress the lethal Gβ phenotype and also identified a maize Gβ allele with weak autoimmune responses but strong development phenotypes. Using these tools, we show that Gβ controls meristem size in maize, acting epistatically with G protein α subunit gene (Gα), suggesting that Gβ and Gα function in a common signaling complex. Furthermore, we used an association study to show that natural variation in Gβ influences maize kernel row number, an important agronomic trait. Our results demonstrate the dual role of Gβ in immunity and development in a cereal crop and suggest that it functions in cross-talk between these competing signaling networks. Therefore, modification of Gβ has the potential to optimize the trade-off between growth and defense signaling to improve agronomic production.

中文翻译：

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玉米异源三聚体G蛋白β亚基控制芽分生组织的发育和免疫反应。

异三聚体G蛋白是受体信号转导的重要转导物，在具有CLAVATA受体的植物中控制分生组织的大小，以及与病原体相关的分子模式受体的基础免疫中的植物起作用。然而，尚未解决异三聚体复合物的特定成员是否增强发育与防御之间的串扰，以及这些功能在物种间的保守程度。在这里，我们使用CRISPR / Cas9敲除了玉米G蛋白β亚基基因（Gβ），发现该突变体具有致命性，与拟南芥中的那些不同，后者的同源突变体具有正常的生长和繁殖力。我们表明，致死性不是由特定的发育停滞引起的，而是由自身免疫引起的。我们使用了遗传多样性筛选来抑制致命的Gβ表型，还鉴定了具有弱自身免疫反应但具有强发育表型的玉米Gβ等位基因。使用这些工具，我们证明Gβ控制玉米的分生组织大小，并与G蛋白α亚基基因（Gα）发生上位性相互作用，表明Gβ和Gα在共同的信号复合物中起作用。此外，我们使用关联研究表明，Gβ的自然变异会影响玉米籽粒行数，这是重要的农艺性状。我们的结果证明了Gβ在谷类作物的免疫和发育中的双重作用，并暗示了它在这些竞争性信号网络之间的串扰中发挥作用。因此，Gβ的修饰具有优化生长和防御信号之间的折衷以改善农艺产量的潜力。