Enterobacter amnigenus W5: A potential causal agent for Rehmannia glutinosa replant problem

Authors Bu, Y. Q.; Xue, Y. R.; Gan, L. S.; Liu, C. H.; Shan, Z. J.

Journal ALLELOPATHY JOURNAL , JUL 2014,1:34

Abstract Rehmannia glutinosa Libosch is an important medicinal plant. However, its production is threatened by soil sickness in continuous cropping. In this study, we isolated a soil bacterium Enterobacter amnigenus W5 from an R. glutinosa replant field. It was identified based on physiological and biochemical characterization and 16S rRNA gene sequence analysis. The culture broth and filtrate of strain W5 showed strong phytotoxic effects on R. glutinosa leaves and roots. One phytotoxic compound, cyclo (Pro-Tyr) was extracted from the culture broth of strain W5. The compound proved toxic to Oxalis corniculata, Malachium aquaticum and R. glutinosa, at 0.05 mu g/mL, 5.00 mu g/mL and 0.50 mu g/mL concentrations, respectively. Moreover, the composition of the tuberous roots of R. glutinosa promoted the growth of strain W5 in a dose-dependent manner in in-vitro test. These results suggested that E. amnigenus W5 with a narrow phytotoxic spectrum, secreted phytotoxic chemical cyclo (Pro-Tyr), which probably is the cause problem in long-term continuous cultivation of R.glutinosa. The methods targeting this bacterium or theliliytotoxic compound could be used to control the long term replant problem of R. glutinosa.

Species covered 酢浆草 Oxalis corniculata 鹅肠菜 Myosoton aquaticum 地黄 Rehmannia glutinosa