Molecular Evolutionary Research Of The Plant LEA Gene Family And Preliminary Functional Analysis Of An Atypical LEA Gene In Arabidopsis

LEA(Late embryogenesis abundant) proteinfs, a kind of stress-related protein, are involved in plant responses to different abiotic stresses. Here, 332 potential LEA gene family members were identified in eleven plant species. Then, the evolution pattern of the LEA gene family in these species was studied by estimation of the maximum number of gained and lost LEA genes. Subsequently, a strong correlation between phylogeny, gene structure, and motif composition was found. The predicted LEA genes were non-randomly distributed within nine chromosomes of tomato, and segmental and tandem duplications were probably important for their expansion. Many cis-elements potentially mediating transcription in response to different abiotic stresses were also found in the promoter region of the LEA genes. An additional intragenic recombination played an important role in the evolution of the LEA genes. Selection analysis also identified some positively selected sites that located on the α-helix or β-turn regions in the protein. Expression analysis using both microarray data and quantitative real-time PCR indicated that LEA genes were widely expressed in various tissues, and that a few members responded to some abiotic stresses. A total of 45 unique genes were exhibited the interaction relationship with LEA genes. Functional categorical analysis showed that these co-expression genes were involved in cellular metabolism and stimulus responses, suggesting that the LEA genes may have similar molecule functions. In addition, the function of At LEA52, an atypical LEA protein in Arabidopsis was preliminary identified in our study. The tissue localization of the AtLEA52 transcription was determined by transgenic technique. We also found that the expression of the AtLEA52 gene was down-regulated in leaves of transgenic Arabidopsis under drought, salt or low temperature treatments. Finally, our study also showed that over-expression of the AtLEA52 gene improved transgenic Arabidopsis seedlings sensitivity to drought or salt stress. Our study provides useful information on the molecular evolution of the plant LEA gene family and the functional mechanism of the atypical LEA gene.