Structure and expression of kin2, one of two cold- and ABA-induced genes of Arabidopsis thaliana.

We report the isolation of the second member, kin2, of a family of two cold-inducible genes of Arabidopsis thaliana. The proteins corresponding to the two genes have similarities to the small antifreeze proteins from Winter flounder. Kin1 and kin2 are organized in a close tandem array in the genome of A. thaliana. Both have three exons separated by introns with approximately the same length and location. The coding regions are highly conserved while the introns and especially the 3' flanking sequences of the mRNAs have diverged. The kin1 and kin2 genes are coordinately regulated in the cold. Unlike kin1, the kin2 mRNA has a detectable basal level, and accumulates to a higher level during acclimation. Both mRNAs are induced by 10 microM ABA but only kin2 responds strongly to drought and salinity stresses.