The Function Analysis Of CYP78A9 Of Capsella Bursa-pastoris And Its Influence In Morphogenesis

The Arabidopsis thaliana and Capsella bursa-pastoris are both Cruciferae plant that have high similar genetic background and physical characters.But they are significantly different in morphology: the Capsella bursa-pastoris show higher height and shorter internode than that of Arabidopsis thaliana,with more fruit pods as well.The Capsella bursa-pastoris' s carpels develop to a heart shape silicle and the Arabidopsis thaliana's carpel is a cylindrical silique.Morphological differences are observed in the early stages of carpel development.It will be a good method to investigate the morphologic development by comparation of their homologous genes.The cytochrome P450 is involved in a variety of compounds synthesis and metabolic pathways in plants.CYP78 A gene is a member in the larger P450 subfamily,and some of its members play an important role in regulating the growth and development in Angiosperms.In this study we cloned the homologous CYP78A9 gene of Capsella bursa-pastoris CbCYP and constructed an overexpression p35S::CbCYP and specific expression pCYP::CbCYP vector and transformed into Arabidopsis thaliana.The transgenic plants were screened out and identified.The morphological development showes that the CbCYP overexpression transgenic with significant enlarged carpel and increased height.They are also with increased pods number and shorter internodes.The carpel morphology of CbCYP specific expression transgenics with only minor difference in plant height and number of pods.But it leads to comprehensive development influence if it is overexpressed.These results suggest that CbCYP involves in the morphology of the carpels and stem segments during morphological development.To investigate the expression difference of the two homologous genes that the GUS reporter vector of Capsella bursa-pastoris and Arabidopsis thaliana CYP78A9 promoter were constructed and transformed into Arabidopsis thaliana in comparison.The GUS staining showed that the expression pattern of Capsella bursa-pastoris was much similar to that of Arabidopsis thaliana but with higher levels in the vegetative growth organs.The level of expression was slowly increased after reproductive growth.During the process of ovule development,it shows a highest level of expression.The Arabidopsis thaliana AtCYP78A9 is not expressed in the stem,but Capsella bursa-pastoris CbCYP was observed at low levels expression in the stem.The GUS activity in the other organs also showes a degree of expression differences.The expression differences between the two genes are due to the different promoter elements.By comparision of the two homologous genes there are difference elements such as gibberellin response elements and photoresponse elements in the promoter region.It is speculated that the differences in the gibberellin regulation system lead to the difference in the expression of the CYP78A9 gene and affect the auxin regulation loop through its metabolic pathway.Thus the CYP78A9 is involved into morphologe development and lead to the difference of the two weeds plant.