Construction And Genetic Transformation In Tomato Of Maize BK2L3 Overexpression Vector

Cell wall is an important ingredient of plant cell structure which is essential for cellular morphology stability and mechanical damage reduction. Meanwhile, cellulose plays an important role in cell wall biosynthesis. It is of great significance to determine the role of COBRA gene family in fruit development and ripening for the reason that COBRA takes part in cell wall biosynthesis. Research has shown that SICOBRA-Like gene is highly expressed in early fruit development and its expression declines dramatically during ripening stages.What’s more, its expreesion in tomato results in endogenous co-suppression. Thus, we attempt to make a study on maize BK2L3 on purpose of prolong the fruit shelf-life and eliminate co-suppression according to genetic engineering method.Maize BK2L3 is the member of COBRA gene family. The full-length cDNA sequence of maize BK2L3 gene was amplified by RT-PCR and pBI121-BK2L3 overexpression vector driven by a fruit-specific promoter TFM7 was made to generate Agrobacerium mediated tomato transformants. Tansgenic plants were obtained after identification by PCR assay.Studies have been made to investigate BK2L3 expression level, content of cellulose, firmness and thickness of pericarp and fruit shelf-life of transgenic and wild-type tomatoes. RT-PCR showed overexpression level of BK2L3 in the transgenic fruits, where there is no expression in the wild-type fruits. Molecular analysis demonstrated that positive transgenic tomatoes display enhanced pericarp thickness. The firmness, cellulose content and shelf life of the transgenic red ripe fruits were higher than those of the wild-type species. Further study indicated that co-suppresion has efficiently eliminated. These results demonstrated that fruit-specific overexpression of maize BK2L3 in tomato could improve fruit quality in terms of cell wall metabolism and shelf life.