The Research On Drought Resistance Mechanism Of Arabidopsis PP6

Abiotic stresses, including drought, high salt, high temperature etc, seriously affect plant growth and development, and reduce the production of crops. Plants have evolved many mechanisms to adapt to these abiotic stresses, of which, the ABA signaling plays a very important role. Our previous work shows that PP6 plays a critical role in regulating auxin transport and ABA signaling, and further plays a key role in regulation of plant growth and development, but it is not clear whether PP6 is involved in regulation of plant abiotic stress response.In this study, we found that the double mutants of PP6 catalytic subunit encoding gene FyPP1 and FyPP3 (f1 f3) are less sensitive to drought stress as compared with Col (wild type control). We also verified the phenotype through measurement of the stomatal aperture and the leaf surface temperature. ABFs, including ABF2, ABF3 and ABF4, are bZIP transcription factors, which play key roles in ABA mediated drought stress response. We found that FyPPl and FyPP3 can interact with ABF2 and ABF4 through Split Luciferase Complementation assay, suggesting that PP6 may regulate the response of plant drought stress through regulate the function of the ABF transcription factors. We also tested the expression of ABF2/3/4 and some marker genes such as RD29A, RD29B, OST1 in fl, f3, f1 f3, Col before and after drought stress, and we found that the expression of ABF2/4, RD29A, RD29B and OST1 were significant upregulated in these materials, but in fl f3 double mutants, the expression ofABF2, ABF4, RD29A, RD29B and OST1 were much higher than Col, f1, f3. OST1 (also known as SnRK2E/SnRK2.6) is a protein kinaseand play roles in drought stress through regulating the phosphorylation of downstream transcription factors, In order to study the genetic interactions between OST1 and PP6, we constructed the ostlfl f3 triple mutant, and found that ostlfl f3 were less sensitive to drought stress thanot1, indicating that OST1 can genetically interact with PP6 to regulate plant response to droght stress.In this research, we deeply studied the function and molecular mechanism of phosphatase PP6 in regulating plant drought response, further expanded the understanding of PP6 biology function. Considering the extreme conservation of PP6 in different plant species, the findings of ourstudy will provide genetic resources and theoretical basis for crop breeding seeking to improve drought resistance.