The Study On Expression Of The Root Tissue-specific Promoter RRB7 In Cotton And Arabidopsis Thaliana

Promoters play an important role in gene expression regulations which decide the time point, tissue location and level of gene expression. Constitutive promoters, which are widely used as commercial plant gene engineering products, facilitate foreign gene expressing in all plant tissues and throughout the plant developmental period. That may squander the plant nutrient and energy, results in increased metabolism burden of plants, often followed by morphology change and even affects growth and development of transgenic plants. Therefore, rRB7 promoter of TobRB7 which specially expressed in root tissue has been cloned, fused with gfp and vgb separately, transfered Arabidopsis and Cotton. The result can be summarized as following:1,Construction of 3 plant expression vector: pGBI121GFP, CaMV35S promoter and gfp form the final cassette; pGBIrRB7GFP, rRB7 promoter and gfp construct the final cassette; pGBIrRB7VHB, rRB7 and vgb construct the final cassette.2,Transfer pGBI121GFP, pGBIrRB7GFP into Arabidopsis by Floral Dipping. 15 and 16 regeneration of T1 plants were obtained independently. Fluorescence scanning different tissues of Arabidopsis by confocal laser scanning microscope. The result indicate rRB7 promoter could drive GFP expressed well in elongate area , mature area of root tip and crown, but the fluorescence intensity is 23.6% lower than CaMV35S promoter control and there is no expression detected in stems and leaves. The result demonstrated that this promoter is a root tissues-specific promoter, however, it is not an efficient promoter, compared with CaMV35S promoter.3,Transferred pGBIrRB7VHB into Gossypium hirsutum variety Y18 by pollen tube pathway transformation method. 15 regeneration cotton plants was obtained by kanamycin screen and PCR analysis. Detecting expression level of vgb driven by rRB7 promoter in root by real-time PCR. The result proved rRB7 promoter can drive vgb especially expressed in root tissues, but the fluorescence intensity is lower than CaMV35S promoter control. The result is similar with that of Arabidopsis. The result of chlorophyll analyze indicates the expression of vgb has little effection on amount of chlorophyll.In this study, the expression specificity of rRB7 promoter in Arabidopsis and cotton were analyzed. Results demonstrated this promoter expressed well especially in root tissue, and fusion with the vgb, which increased the tolerance to flood. That makes one step forward for using the promoter rRB7 to make some progress in plant root tissue gene engineering. And it looks forward to be used in increasing the absorption of water, fertilization, microelement, the resistance to diseases and insects infected through soil as well as living ability in special environment.