RESPONSE OF PEA (PISUM-SATIVUM L) GENOTYPES TO AGROBACTERIUM AS A MEANS OF PROBING THEIR ENDOGENOUS HORMONE LEVELS

We have transformed different pea genotypes, some which exhibit nodula tion-defective or supernodulation phenotypes, with two distinct Agroba cterium strains to examine their endogenous hormone balance. Varying r esponses to A. tumefaciens or A. rhizogenes revealed pea genotypes tha t had unusual hormone levels or sensitivity to phytohormones. This was confirmed by HPLC and ELISA analysis as well as by investigating the effects of exogenous auxin and cytokinin on the transformation respons es of the different genotypes. The differences among the genotypes in forming either roots or tumors upon infection with Agrobacterium enabl ed us to carry out a genetic analysis of these traits. We found that t he capacity for root formation was inherited as a monogenic, dominant trait whereas the ability to form tumors was polygenic. These results suggest that these genes may be important for the regulation of endoge nous phytohormone levels. (C) 1998 Elsevier Science Ireland Ltd. All r ights reserved.