The Development Of Grafts Of Arabidopsis And Macromolecule Transportation Between The Graft Partners

Using semithin sections techniques the histological development of the autograft Arabidopsis thaliana( Columbia24 ecotype) were examined. In autograft of Arabidopsis thaliana( Columbia24 ecotype) grafted in the position of hypocotyls, wound xylem and sieve elements were differentiated in the tissues both of scion and stock 4 days after grafting. Continuous wound vascular bridges connecting both partners across the graft union were found 7 days after grafting. In autograft from inflorescence stems callus tissue was found 4 days after grafting. No xylem and sieve elements were differentiated in both scion and stock in this period. 8 days after grafting, most part of the necrosis layer in the graft union disappeared and Continuous wound vascular bundle connecting both graft partners could be recognized. The number of vascular connections across graft interface was increased with the days after grafting.6(5)CF, a kind of phloem transport tracer, was used to test the functioning of the wound phloem across the graft union. 6(5)CF was introduced from the leaves of the scion into autograft of C24 inflorescence stem 8 days after grafting. After 12h-long transport, 6(5)CF could be detected in the stock by using fluorescence microscopy. The result of transport was accord with the histological observation.Different hetrograft combinations were created between wild type Arabidopsis(C24), MP17:GFP-transgenic Arabidopsis named At9, and the lew2-1 mutant with a phenorype of collapsed xylems, for studying the macromolecule transportation. In the graft combination of At9 on lew2-1, the phenotype of collapsed xylems in the lew2-1 stock could be improved greatly. Using the RT-PCR technique and treatment with endonuclease, the transport of IRXI mRNA from scion into stock were detected. In the hetrograft combinations, C24 on lew2-1 and lew2-1 on At9, no evidence was found that IRX1 mRNA could be transported between the graft partners. The direction of IRX1 mRNA transport was from shoot into rootsystem.