Heat-inducible C3HC4 type RING zinc finger protein gene from Capsicum annuum enhances growth of transgenic tobacco

Capsicum annuum RING Zinc Finger Protein 1 (CaRZFP1) gene is a novel C3HC4-type RING zinc finger protein gene which was previously isolated from a cDNA library for hot pepper plants treated of heat-shock. The CaRZFP1 was inducible to diverse environmental stresses in hot pepper plants. We introduced the CaRZFP1 into the Wisconsin 38 cultivar of tobacco (Nicotiana tabacum) by Agrobacterium mediated transformation under the control of the CaMV 35S promoter. Expression of the transgene in the transformed tobacco plants was demonstrated by RNA blot analyses. There appeared no adverse effect of over-expression of the transgene on overall growth and development of transformants. The genetic analysis of tested T-1 lines showed that the transgene segregated in a Mendelian fashion. Transgenic tobacco lines that expressed the CaRZFP1 gene were compared with several different empty vector lines and they exhibited enhanced growth; they have larger primary root, more lateral root, larger hypocotyls and bigger leaf size, resulting in heavier fresh weight. Enhanced growth of transgenic lines accompanied with longer vegetative growth that resulted in bigger plants with higher number of leaves. Microarray analysis revealed the up-regulation of some growth related genes in the transgenic plants which were verified by specific oligomer RNA blot analyses. These results indicate that CaRZFP1 activates and up-regulates some growth related proteins and thereby effectively promoting plant growth.