Chrysanthemum cultivar Agrobacterium interactions revealed by GUS expression time course experiments

Nine 24-day GUS expression time course experiments involving 2760 leaf explants revealed complex host-bacterium interactions between four cultivars of florists' chrysanthemum from two sources (in vitro and glasshouse) and four disarmed strains of Agrobacterium tumefaciens (EHA105, LBA4404, MOG101, MOG301) containing the binary vectors pMOG410 or pKIWI110. Cultivars Peach Margaret and Yellow Lucondra [Dendranthema Grandiflorum] were more easily transformed than cv. Korean [Dendranthema zawadskii x D. grandiflorum] and cv. Nightingale [Dendranthema Grandiflorum]. Agrobacterium strains EHA105 and MOG101, containing pMOG410, gave greater numbers of blue-stained units per explant on average, over 24 days, for all four cultivars and explant sources compared with strain MOG301 containing pMOG410 or strain LBA4404 containing pKIWI110. However, comparison of expression of the gusA gene from the T-DNAs of pMOG410 or pKIWI110 of strain LBA4404, in explants from the glasshouse source of cultivars Peach Margaret and Yellow Lucondra, revealed that the binary vector pKIWI110 was failing rather than strain LBA4404. The source of explant affected gene transfer frequencies most noticeably for cultivars Peach Margaret and Yellow Lucondra. Explants from in vitro sources gave higher levels of stable gusA expression after inoculation with Agrobacterium and selection on regeneration medium containing kanamycin than those from glasshouse sources. (C) 1998 Elsevier Science B.V. All rights reserved.