Mutations at two new Arabidopsis ABA response loci are similar to the abi3 mutations

Summary Two new Arabidopsis loci involved in ABA response, ABA‐ i nsensitive ( ABI ) 4 and ABI5 , have been identified by mutation. The abi4 and abi5 mutants were characterized in terms of ABA sensitivity of seed germination, dormancy, seed‐specific gene expression and stomatal regulation. Their phenotypes are similar to mutations in ABI3 , which is thought to encode a seed‐specific transcriptional activator. Analysis of double mutants combining abi4 and abi5 mutations with abi1, abi2 or a bi3 mutations also suggests that ABI4 and ABI5 act in the same transduction pathway as ABI3 .