Department of Applied Plant Science, College of Agriculture and Life Science, Chonnam National University, Gwangju 61186, Republic of Korea.
Biosciences and Biotechnologies Institute of Aix-Marseille, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Centre National de la Recherche Scientifique and Aix-Marseille University, Commissariat à l'Énergie Atomique et aux Énergies Alternatives Cadarache, 13108 Saint-Paul-lez-Durance, France.
Plant Physiol. 2020 Nov;184(3):1482-1498. doi: 10.1104/pp.20.00630. Epub 2020 Aug 28.
Patatin-related phospholipase As (pPLAs) are major hydrolases acting on acyl-lipids and play important roles in various plant developmental processes. pPLAIII group members, which lack a canonical catalytic Ser motif, have been less studied than other pPLAs. We report here the characterization of in Arabidopsis () based on the biochemical and physiological characterization of knockouts, complementants, and overexpressors, as well as heterologous expression of the protein. In vitro activity assays on the purified recombinant protein showed that despite lack of canonical phospholipase motifs, pPLAIIIα had a phospholipase A activity on a wide variety of phospholipids. Overexpression of in Arabidopsis resulted in a decrease in many lipid molecular species, but the composition in major lipid classes was not affected. Fluorescence tagging indicated that pPLAIIIα localizes to the plasma membrane. Although Arabidopsis knockout mutants showed some phenotypes comparable to other , such as reduced trichome length and increased hypocotyl length, control of seed size and germination were identified as distinctive -mediated functions. Expression of some genes was strongly reduced in the mutants. Overexpression of caused increased resistance to turnip crinkle virus, which associated with a 2-fold higher salicylic acid/jasmonic acid ratio and an increased expression of the defense gene pathogenesis-related protein1. These results therefore show that has functions that overlap with those of other but also distinctive functions, such as the control of seed germination. This study also provides new insights into the pathways downstream of .
类脂酶 PLAIII （pPLAs）是作用于酰基脂的主要水解酶，在各种植物发育过程中发挥重要作用。与其他 pPLAs 相比，缺乏典型催化 Ser 基序的 pPLAIII 组成员研究较少。我们根据 敲除、互补和过表达突变体的生化和生理学特性，以及蛋白的异源表达，对拟南芥中的 pPLAIIIα 进行了鉴定。对纯化的重组蛋白进行的体外活性测定表明，尽管缺乏典型的磷脂酶基序，但 pPLAIIIα 对各种磷脂具有磷脂酶 A 活性。拟南芥 pPLAIIIα 的过表达导致许多脂质分子种类减少，但主要脂质类别的组成不受影响。荧光标记表明 pPLAIIIα 定位于质膜。尽管 pPLAIIIα 敲除突变体表现出一些与其他 pPLAs 相似的表型，如毛状体长度减少和下胚轴长度增加，但种子大小和萌发的控制被鉴定为 pPLAIIIα 介导的特有功能。一些 基因的表达在 突变体中强烈降低。pPLAIIIα 的过表达导致对芜菁花叶病毒的抗性增加，这与水杨酸/茉莉酸比值增加 2 倍和防御基因病程相关蛋白 1 的表达增加有关。因此，这些结果表明 pPLAIIIα 具有与其他 pPLAs 重叠的功能，但也具有独特的功能，如控制种子萌发。本研究还为 下游途径提供了新的见解。
