Evidence for Host Genome Involvement in Cytokinin Metabolism by Male and Female Cells of Mercurialis annua Transformed by Strain 15,955 of Agrobacterium tumefaciens

When male and female individuals of a dioecious species Mercurialis annua L. were inoculated with the same strain of Agrobacterium tumefaciens (15,955), the corresponding tumor tissues of each sex clearly differed in their endogenous cytokinin content; only the male tumors had a morphogenetic feminizing effect on male flowers.

In male tumor tissues, zeatin (Z) in higher quantity than ribosyl-zeatin (RZ) became the major metabolite in contrast with the general situation for crown-galls; the female tumor tissues were characterized by an increase of total endogenous cytokinins and by the appearance of some specific metabolites such as a methyl-thio-Z and several glycosylated Z derivatives that had not been detected in healthy apices.

In both male and female tumor tissues, the cis form of RZ, present in healthy apices as 30% of trans-RZ form, was no longer detectable.

Quantitative and qualitative differences characterize male and female tumor tissues (host genes expression) but since differences also appeared between healthy male and female apices and their corresponding tumor tissues (TDNA gene expression), it can be tentatively concluded that a complex interaction between host cytokinin genes and those of TDNA control the endogenous metabolism of tumor tissues.