Gain‐of‐function and loss‐of‐function phenotypes of the protein phosphatase 2C HAB1 reveal its role as a negative regulator of abscisic acid signalling

• DOI: 10.1046/j.1365-313x.2003.01966.x
• Publication Date: 2004-01-20T11:52:45Z
• Authors: Angela Saez; Nadezda Apostolova; Miguel Gonzalez‐G...; Mary Paz Gonzalez...; Carlos Nicolas; Oscar Lorenzo; Pedro L. Rodriguez
• Keywords: Wild type; Cauliflower mosaic virus

Summary HAB1 was originally cloned on the basis of sequence homology to ABI1 and ABI2 , indeed, a multiple alignment 32 Arabidopsis protein phosphatases type‐2C (PP2Cs) reveals cluster composed by four closely related proteins, ABI1, ABI2, At1g17550 (here named HAB2). Characterisation transgenic plants harbouring transcriptional fusion Pro : green fluorescent ( GFP ) indicates that is broadly expressed within plant, including key target sites abscisic acid (ABA) action as guard cells or seeds. The expression mRNA in vegetative tissues strongly upregulated response exogenous ABA. In this work, we show constitutive under cauliflower mosaic virus (CaMV) 35S promoter led reduced ABA sensitivity both seeds tissues, compared wild‐type plants. Thus, field signalling, work represents an example stable phenotype planta after sustained overexpression PP2C genes. Additionally, recessive T‐DNA insertion mutant analysed whereas previous studies alleles genes were carried out with intragenic revertants abi1‐1 abi2‐1 mutants carry missense mutations conserved regions domain. presence ABA, hab1‐1 shows ABA‐hypersensitive inhibition seed germination; however, its transpiration rate similar together 35S:HAB1 are consistent role negative regulator signalling. Finally, these results provide new genetic evidence function