An Arabidopsis homolog of importin 1 is required for ABA response and drought tolerance

作者：Luo, Yanjie; Wang, Zhijuan; Ji, Hongtao; Fang, Hui; Wang, Shuangfeng; Tian, Lining^*; Li, Xia

来源：Plant Journal, 2013, 75(3): 377-389.

DOI：10.1111/tpj.12207

• Arabidopsis thaliana
• Importin 1
• ABA response
• nuclear importin
• nuclear proteins
• drought resistance

The import of proteins into the nucleus in response to drought is critical for mediating the reprogramming of gene expression that leads to drought tolerance. However, regulatory mechanisms involved in nuclear protein import remain largely unknown. Here, we have identified an Arabidopsis gene (AtKPNB1) as a homolog of human KPNB1 (importin 1). AtKPNB1 was expressed in multiple organs, and the protein was localized in the cytoplasm and nucleus. AtKPNB1 was able to facilitate nuclear import of a model protein. Null mutation of AtKPNB1 delayed development under normal growth conditions and increased sensitivity to abscisic acid (ABA) during seed germination and cotyledon development. Inactivation of AtKPNB1 increased stomatal closure in response to ABA, reduced the rate of water loss, and substantially enhanced drought tolerance. AtKPNB1 interacted with several importin proteins, nucleoporin AtNUP62, and the Arabidopsis Ran proteins. Inactivation of AtKPNB1 did not affect the ABA responsiveness or the expression level or subcellular localization of ABI1, ABI2 or ABI5, key regulators of the ABA signaling pathway. Moreover, phenotypic analysis of epistasis revealed that AtKPNB1 modulates the ABA response and drought tolerance through a pathway that is independent of ABI1 and ABI5. Collectively, our results show that AtKPNB1 is an Arabidopsis importin that functions in ABA signaling.

• 出版日期2013-8
• 单位中国科学院遗传与发育生物学研究所; 植物细胞与染色体工程国家重点实验室