Phylogenetic and expression analysis of ZnF-AN1 genes in plants.

In plants, ZnF-AN1 genes are part of a multigene family with 13 members in Arabidopsis thaliana, 19 members in Populus trichocarpa, 17 members in Oryza sativa, at least 11 members in Zea mays, and 2 members in Chlamydomonas reinhardtii. All ZnF-AN1 genes contain the ZnF-AN1 domain. According to the phylogenetic analysis of the ZnF-AN1 domain, we divided plant ZnF-AN1 genes into two types. The coding sequences of most type I members do not possess any introns, while most type II members do possess intron(s). Through Northern blot analysis of maize members and digital Northern analysis of Arabidopsis members, we found that most ZnF-AN1 genes are involved in responses to abiotic stresses. The evolutionary analysis indicated that the expansion rate of type I was higher than that of type II. After expansion, some ZnF-AN1 genes may have gained new functions, some may have lost their functions, and some were specialized to perform their functions in stress-specific or tissue-specific modes. In addition, we propose an evolutionary model of type II ZnF-AN1 genes in plants.