Potential of Bacillus subtilis for controlling bacterial leaf blight pathogen in rice

K.S Ku Asmah,Z Sapak

doi:10.26656/fr.2017.4(s5).011

Abstract

Bacterial leaf blight (BLB) of rice is an economically important disease caused by Xanthomonas oryzae pv. oryzae (Xoo) throughout the world. To control this disease, bacterial isolate of Bacillus subtilis UiTMB1 was screened for the antagonistic activity against the pathogen in vitro and in vivo studies. A bacterial assay and detached leaf technique were used to evaluate the potential of the bacterium against BLB pathogen in the laboratory. Meanwhile, the glasshouse study was conducted to further examine the aptitudes of the isolate on the disease control and growth-promoting of rice plants. The findings revealed that B. subtilis UiTMB1 is able to control the disease and enhance the growth of rice plants. Rice plants treated with B. subtilis UiTMB1 before being inoculated with BLB pathogen showed less severe disease symptoms with low disease severity index of 3.43 compared to rice plants without B. subtilis UiTMB1 with high disease severity index of 8.4. Besides controlling the disease, B. subtilis UiTMB1 was also promoting plant height, chlorophyll content, number of tillers and biomass of rice plants.

Highlights

Rice is considered a major crop and the main source of diet in Malaysia
The findings showed that the rice plants treated with B. subtilis UiTMB1 prior to inoculation with the Bacterial leaf blight (BLB) pathogen (T2P- preventive) recorded only 3.43% disease severity index (DSI) at six weeks of observation as compared to the rice plants treated with the BLB first, B. subtilis UiTMB1 (4.50% DSI) (T1C- curative)
These results suggested that B. subtilis UiTMB1 has potential to protect rice plants from a severe infection of the BLB pathogen (Figure 2)

Summary

Introduction

Rice is considered a major crop and the main source of diet in Malaysia. The rice consumption pattern of the adult population in this country shows that Malaysians consume an average of two and a half plates of rice per day (Norimah, 2008). In 2014, approximately 679,239 ha were cultivated with rice and were planted twice a year (Department of Agriculture of Malaysia, 2015). According to Man and Sadiya (2009), there were approximately 116, 000 out of 296,000 rice growers in Malaysia which are full-time growers who depend on rice cultivation for their livelihood. Bacterial leaf blight (BLB) of rice caused by Xanthomonas oryzae pv. A previous study by Saad (2000) stated that cultivation of susceptible rice variety MR84 attacked by BLB in 1988 to 1994 had caused a huge loss estimated about RM 50 million during those years. Gangwar and Sinha (2010) and Dipankar et al (2017) reported that Trichoderma harzianum and Pseudomonas fluorescens have potential as bio-control agents for BLB disease in India.

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Conclusion