Comparative analysis of the variable 3' UTR and gene expression of the KIN and KIN-homologous LEA genes in Capsella bursa-pastoris.

As the crucial members of the cold-regulated (COR) gene family, KIN genes are involved in diverse abiotic stress responses in plants. In the present study, KIN genes from the widespread plant Capsella bursa-pastoris were identified and analyzed to better understand the powerful adaptation of this species. Two KIN genes were cloned and sequenced by 3' RACE. As some COR genes are homologous to LEA genes, three KIN-homologous LEA genes were also identified. We deduced the amino acid sequences of the five proteins to estimate their phylogenetic relationships, and grouped them into three subfamilies (CI, CII, and CIII). Variable 3' UTRs were found in CI, CII, and CIII genes. Using qPCR, we evaluated the transcriptional levels of the five genes in different organs and embryonic stages. Two CI genes were exclusively expressed in early embryos and flowers. The CII and CIII genes showed obvious up-regulation in young leaves after heat stress, cold stress, and ABA treatment. Two of the CI genes, however, rarely responded to those stresses in young leaves. In contrast, all five genes showed differential responses in flowers when C. bursa-pastoris plants were sprayed with ABA. Furthermore, the expression of these genes in C. bursa-pastoris was compared to that of the corresponding Arabidopsis genes, and similar gene expression profiles were found in both species. Our findings suggest that these five genes play different roles in development and the responses to abiotic stresses in C. bursa-pastoris. Key message We characterized two KIN and three KIN-homologous LEA genes, and analyzed their variable 3'UTR and organ-specific, embryo-developmental, stress-induced gene expression in Capsella bursa-pastoris.