Identification Of Tomato DR8 Transgenic Lines

DR8 gene was isolated from tomato fruit by differential screening of gene expression during tomato fruit development and ripening and it is a member of Aux/IAA family. Importantly, its mRNA accumulation is regulated by auxin and ethylene during fruit development and ripening, indicating that it participate to the ethylene-dependent regulation of gene expression in fruit. This research aimed to study the function of DR8 in whole plant growth and fruit development by construction of DR8 transgenic lines.The main contents and results of the experiments are the following:(1) Identification of DR8 transgenic tomato lines by PCR and RT-PCR experiments. The results is that S58, S60, S62, S106 and S115 are all antisense lines. And DR8 can downregulate or upregulate the expression of DR4, so it is proved to be a member of Aux/IAA family, and the encoded protein is a downregulation factor in auxin response;(2) Observation on phenotypes of AS-DR8 tomato lines and functional analysis of DR8 gene. The results is that DR8 regulate fruit development by downregulation or upregulation of DR4: when it is downregulated, the fruiting rate is higher than WT(Wild-type)and the fruit can develop to ripening phase. On the contrary, the lower fruiting rate and inhabited development, so the fruit fall in early period. Moreover, DR8 is a key regulation factor in the process of apical dominance and root morphogenesis, and its encoded protein is a inhabitor on shoot branching and root branching. At last, it can regulate leaf morphogenesis by influencing the process of cell growth, division and differentiation, this result in vascular network patterning and leaf ontogeny.In a word, tomato DR8 gene belongs to Aux/IAA family and its encoded protein is a downregulation factor in auxin response and it can regulate expression of auxin-induced genes. Moreover, it is a key regulation factor in the process of fruit development, apical dominance, root morphogenesis and leaf ontogeny.On the basis of functional analysis of DR8 , some advice is put forward for further study.