The oomycete Phytophthora infestans is a notorious plant pathogen with potato and tomato as its primary hosts. Previous research showed that the heterotrimeric G-protein subunits Gα and Gβ have a role in zoospore motility and virulence, and sporangial development, respectively. Here, we present analyses of the gene encoding a Gγ subunit in P. infestans, Pigpg1. The overall similarity of PiGPG1 with non-oomycete Gγ subunits is low, with only the most conserved amino acids maintained, but similarity with its homologs in other oomycetes is high. Pigpg1 is expressed in all life stages and shows a similar expression profile as the gene encoding the Gβ subunit, Pigpb1. To elucidate its function, transformants were generated in which Pigpg1 is silenced or overexpressed and their phenotypes were analyzed. Pigpg1-silenced lines produce less sporangia, which are malformed. Altogether, the results show that PiGPG1 is crucial for proper sporangia development and zoosporogenesis. PiGPG1 is a functional Gγ, and likely forms a dimer with PiGPB1 that mediates signaling.

中文翻译：

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疫霉疫霉的G蛋白γ亚基参与孢子囊发育。

卵菌疫霉菌是臭名昭著的植物病原体，主要以马铃薯和番茄为宿主。先前的研究表明，异源三聚体G蛋白亚基Gα和Gβ分别在游动孢子的活力和毒力以及孢子囊的形成中起作用。在这里，我们提出了在P. infestans，Pigpg1中编码Gγ亚基的基因的分析。PiGPG1与非卵菌Gγ亚基的总体相似性很低，仅保留了最保守的氨基酸，但与其他卵菌同源物的相似性很高。Pigpg1在所有生命阶段均表达，并显示与编码Gβ亚基Pigpb1的基因相似的表达谱。为了阐明其功能，产生了其中Pigpg1沉默或过表达的转化子，并对其表型进行了分析。Pigpg1沉默的品系产生的孢子囊减少，格式错误。总之，结果表明PiGPG1对于适当的孢子囊发育和游动孢子发生至关重要。PiGPG1是功能性Gγ，可能与PiGPB1形成二聚体，介导信号传导。