Characterization of a putative tomato transcription factor, cLEX4I22

Plants are known to respond well and adapt to various environmental stresses. To identify the plant stress-responsive genes, we have obtained a large number of tomato cDNA clones that responsed to various environmental stresses, by using our homemade cDNA microarray systems. It was interesting to observe that some genes were highly expressed as a response to water deficit, salinity and low temperature stresses. One putative transcription factor, cLEX4I22, apparently belongs to a C2H2 zinc finger protein group, was chosen for this study. In animal systems, the C2H2 zinc finger protein gene family is known as the largest group of regulatory proteins and plays similar roles an important role in growth and development of a number of tested systems. It is thus hypothesized that cLEX4I22 and its homologues transcription factors may also play similar roles in plants. My study goal is to characterize this novel putative transcription factor of tomato, cLEX4I22, for functional analysis and potential application to crop plant development. Southern blot analysis showed that the endogenous cLEX4I22 apparently exist as a single copy gene in the tomato genome; Northern blot analysis of different organs revealed that the cLEX4I22 gene was expressed higher in tomato flowers then other tested organs. In addition, transgenic approach was used for functional study. We have obtained a full length cLEX4I22 cDNA, and cloned the open reading frame of cLEX4I22 into a pCAMBIA1390 binary vector, driven by a constitutive promoter CaMV35S or an Arabidopsis stress-inducible promoter cor15a. Using Agrobacterium-mediated transformation, we have obtained several putative Arabidopsis transgenic lines overexpressing cLEX4I22, which exhibited abnormal phenotypes. These results suggest that cLEX4I22 might play a role in plant growth and development.