Functional Analysis Of AtCDPK1 In Arabidopsis Response To Pseudomonas Syringae And Abiotic Stresses

In plants, intracellular Ca2+ levels are modulated in response to various signals including abiotic and biotic stresses, and specific calcium signatures can be transduced into downstream effects by different calcium sensors. Calcium-dependent protein kinase (CDPKs) are unique calcium sensors in higher plants and are likely to be crucial mediators of diverse calcium signaling cascades induced by development cues, abiotic and biotic stress signals. However, the precise biological function of most CDPKs remains elusive. In this dissertation, the role of Arabidopsis AtCDPK1 in response to Pseudomonas syringe and abiotic stresses were investigated, and the following results were obtained:1. The transcript of AtCDPK1 was induced by both virulent and avirulent P.S. Its expression also was altered by saline, drought, cold, and heat stress and was induced by SA, MeJA and ABA treatment.2. Partial loss-of-function T-DNA insertion mutant of AtCDPK1 leads to slightly decreased expression of PR1, PR2 and AIG1 after inoculation with avirulent Pst avrRpt2. However, mutant plants did not show significant difference compared to wild- type plants in phenotypes after inoculation with virulent Pst DC3000. The stomata of the mutant were kept open at 1hr after Pst DC3000 infection, while closed in the wild-type.3. Ectopic expression of constitutively active AtCDPK1 resulted in more resistance to high salinity stress in terms of their seed germination and seedling growth compared with the wild type.In conclusion, the transcriptional expression of AtCDPK1 was induced by both pathogenic bacteria and abiotic stresses, and was most likely as a positive regulator in defense response and salt stress signaling pathways.