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ARS Home » Research » Publications at this Location » Publication #165565
Title: DECREASED INCIDENCE OF DISEASE CAUSED BY SCLEROTINIA SCLEROTIORUM AND IMPROVED PLANT VIGOR OF OILSEED RAPE WITH BACILLUS SUBTILIS TU-100

Author
item HU, X. - OIL CROPS RES. INST., CHI
item Roberts, Daniel
item JIANG, M. - OIL CROPS RES. INST.
item ZHANG, Y. - OIL CROPS RES. INST.

Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2005
Publication Date: 3/3/2005
Citation: Hu, X., Roberts, D.P., Jiang, M., Zhang, Y. 2005. Decreased incidence of disease caused by Sclerotinia sclerotiorum and improved plant vigor of oilseed rape with Bacillus subtilis Tu-100. Applied Microbiology and Biotechnology. 68:802-807.

Interpretive Summary: Sclerotinia sclerotiorum can cause serious yield losses in oilseed crops in the United States and worldwide. Chemical control measures for diseases caused by this pathogen are often ineffective and can be hazardous to man and the environment. Other control measures such as plant breeding have met with limited success. Biological control measures for these diseases need to be developed due to environmental problems associated with existing chemical controls and the limited effectiveness of other control measures. In this study we show that the beneficial bacterium Bacillus subtilis Tu-100 significantly suppressed incidence of disease caused by S. sclerotiorum on oilseed rape in two of two field trials. Yield was significantly increased in treatments containing this bacterium in one of two field trials. Experiments reported here also identify this bacterium as an endophyte. This information will be useful to scientists devising strategies for biological control of diseases on oilseed crops through enhancement of growth on seeds or of disease suppression.

Technical Abstract: Sclerotinia sclerotiorum can cause serious yield losses in oilseed crops worldwide. Bacillus subtilis Tu-100, isolated from the rhizosphere of oilseed rape, inhibited mycelial growth of S. sclerotiorum Ss-1 on Potato Dextrose Agar and on detached oilseed rape leaves. Isolate Tu-100 also promoted growth of hydroponically-grown oilseed rape. Oilseed rape plants were approximately 15 % greater in dry weight (P < 0.0001) and 6 % greater in length (P < 0.0025) after 90 days when grown in the presence of isolate Tu-100 in Hoagland's solution than with the noninoculated control. B. subtilis Tu-100 significantly reduced (P < 0.05) incidence of disease caused by S. sclerotiorum at harvest in two consecutive trials conducted in fields artificially infested with S. sclerotiorum isolate Ss-1. Mean plant dry weight was significantly greater (P < 0.05) and mean plant length was significantly greater (P < 0.07) in both field trials at the seven true leaf stage with the treatment containing isolate Tu-100 than with the control. In addition, mean seed yield per 120 plants at harvest was significantly greater (P < 0.05) in the second field trial with treatments containing isolate Tu-100. In gnotobiotic studies, the lacZ-tagged-strain B. subtilis Tu-100(pUC18) was detected within all roots of oilseed rape in the region of lateral root formation. Isolate Tu-100 did not persist in the ectorhizosphere of oilseed rape. Populations of this isolate decreased from 8.5 X 108 CFU per seed to approximately 102 CFU per plant ectorhizosphere within 30 days of sowing in autoclaved soil. Isolate Tu-100 was very stable at 25 oC for 6 months in an alginate formulation in a shelf life study. Experiments detailed in this report demonstrate the B. subtilis Tu-100 is an excellent candidate for development as a biological control agent for suppression of S. sclerotiorum on oilseed rape.