Influence of nodulation by the cytokinin producing Rhizobium strain IC3342 on growth and endogenous cytokinin contents in the compatible host cowpea (Vigna unguiculata)

摘要

The Rhizobium strain IC3342 is known to induce leaf curl syndrome in the legume pigeonpea by causing hormonal imbalance or overproducing cytokinins. The effect of this enhanced endogenous cytokinin on morphology, growth and development of cowpea (Vigna unguiculata) was studicd. Three predominant cytokinins, viz. t-ZR (trans-zeatin riboside), DHZR (dihydro zeatin riboside) and iPA (isopentenyl adenine) were estimated in IC3342 culture supernatant by indirect ELISA. The cytokinin levels increased up to 20-fold and DHZR was found to be the predominant cytokinin in xylem sap and leaves of cowpea treated with this Rhizobium strain. These plants also showed a significant increase in chlorophyll content and branch number, both classical formative effects of cytokinin. The overall effect of the high cytokinin-producing strain was more favourable than the native strain.