Zimmerman Jayde A, Verboonen Benjamin, Harrison Hanson Andrew P, Arballo Luis R, Brusslan Judy A
Southern California Coastal Water Research Project Costa Mesa California USA.
University of California, Riverside Riverside California USA.
Plant Direct. 2024 Sep 24;8(9):e70006. doi: 10.1002/pld3.70006. eCollection 2024 Sep.
Extracellular vesicles (EVs) are membrane-bound exosomes secreted into the apoplast. Two distinct populations of EVs have been described in Arabidopsis: PEN1-associated and TET8-associated. We previously noted early leaf senescence in the single and double mutant. Both PEN1 and PEN3 are abundant in EV proteomes suggesting that EVs might regulate leaf senescence in soil-grown plants. We observed that TET8 is more abundant in the apoplast of early senescing and mutant rosettes and in older wild-type (WT) rosettes. The increase in apoplast TET8 in the mutant did not correspond to increased mRNA levels. In addition, apoplast TET8 was more abundant in the early leaf senescence mutant, meaning the increase in apoplast TET8 protein during leaf senescence is not dependent on or . Genetic analysis showed a significant delay in leaf senescence in double mutants after 6 weeks of growth suggesting that these two tetraspanin paralogs operate additively and are positive regulators of leaf senescence. This is opposite of the effect of and mutants that show early senescence and suggest PEN1 to be a negative regulator of leaf senescence. Our work provides initial support that apoplast-localized TET8 in combination with TET3 positively regulates age-related leaf senescence in soil-grown Arabidopsis plants.
细胞外囊泡（EVs）是分泌到质外体中的膜结合外泌体。拟南芥中已描述了两种不同类型的细胞外囊泡：与PEN1相关的和与TET8相关的。我们之前注意到单突变体和双突变体中叶片早衰。PEN1和PEN3在细胞外囊泡蛋白质组中都很丰富，这表明细胞外囊泡可能调节土壤生长植物中的叶片衰老。我们观察到，TET8在早衰和突变莲座叶的质外体以及较老的野生型（WT）莲座叶中更为丰富。突变体中质外体TET8的增加与mRNA水平的增加不对应。此外，质外体TET8在叶片早衰突变体中更为丰富，这意味着叶片衰老过程中质外体TET8蛋白的增加不依赖于或。遗传分析表明，生长6周后，双突变体叶片衰老显著延迟，这表明这两个四跨膜蛋白旁系同源物具有累加作用，是叶片衰老的正调节因子。这与显示早衰的和突变体的作用相反，表明PEN1是叶片衰老的负调节因子。我们的工作提供了初步支持，即质外体定位的TET8与TET3结合可正向调节土壤生长的拟南芥植物中与年龄相关的叶片衰老。
