Genetic impairment in two type 2C proteinphosphatases (PP2C), AHG1 and AHG3, causedstrong ABA hypersensitivity in germination.Upper panel, expression pattern in seeds; lower,ABA sensitivity in germination. 

The PYR1-type ABA receptor binds to PP2Cs and inhibits their activity in the presence of ABA.It subsequently induces activation of SnRK2 protein kinases that activate a series of ABA responsive mechanisms, such as transcription factors and transporters.

 
ahg2-1 exhibits hypersensitivity to both ABA and salicylic acid (SA), which are believed to function in a mutually antagonistic fashion. Analyzing this mutant is expected to provide new clues to dissect the complex interaction between these two hormones. AHG2 encodes enzymes involved in RNA degradation indicating RNA metabolisms somehow take part in the hormone responses and interactions.