Abstract
Cuscuta japonica differentiates haustoria, the absorptive organs necessary for parasitizing host plants. We previously accomplished efficient induction of haustorium formation on Cuscuta seedlings with two different treatments: either with cytokinin or with far-red light plus contact stimuli. The fact that exogenous cytokinin is effective to induce Cuscuta haustoria suggests the possibility of the increase in the endogenous cytokinin level in Cuscuta treated with far-red light and contact stimuli. To inquire such possibility, we examined expression patterns of response regulator genes that respond quickly to cytokinin in Cuscuta following the treatment of far-red light and contact stimuli. Expression of Cuscuta response regulator genes was induced within 2 hours and maintained up to 24 hours following the induction treatment, suggesting the increase in the level of endogenous cytokinin prior to the haustorium formation. The involvement of the endogenous cytokinin level in the haustorium differentiation in Cuscuta will be discussed.
