Characterization of LEA genes in Dendrobium officinale and one Gene in induction of callus.

Abstract Late embryogenesis abundant (LEA) proteins are widely involved in plant stress responsive, while their involvement in callus formation is largest unknown. In this study, we identified and conducted expression analysis of the LEA genes from Phalaenopsis equestris and Dendrobium officinale, and characterized a LEA gene from D. officinale. A total 57 and 59 LEA genes were identified in P. equestris and D. officinale, respectively. A phylogenetic analysis showed that AtM, LEA_5 and Dehydrin groups were absent in both orchids. LEA_1 group genes were strongly expressed in seeds, significantly down-regulated in flowers, and absent in vegetative organs (leaves, stems and roots) in both orchids. Moreover, LEA_1 and LEA_4 group genes from D. officinale were abundant in the protocorm-like body stage and were dramatically up-regulated in response to abscisic acid and salinity stress. A LEA_1 gene (DoLEA43) was selected for further functional analysis. DoLEA43 protein was localized in the cytoplasm and nucleus, and its promoter contained a WUN-motif that was modulated by wounding. Overexpression of DoLEA43 in Arabidopsis enhanced callus induction, causing changes to callus formation-related genes such as WIND1. Our results indicate the involvement of LEA genes in the induction of callus, which provide insights into plant regeneration.