Identification and Characterization of Bacillus SPP with Antagonistic Potential against Phytophthora Palmivora of Durian and Other Perennial Crops

Tan, Shin Ning (2021) Identification and Characterization of Bacillus SPP with Antagonistic Potential against Phytophthora Palmivora of Durian and Other Perennial Crops. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Durian has substantial economic value in Malaysia. Recently, the production volume of durian in Malaysia has been boosting up to a new level due to the rapidly increasing overseas demand for durian. Nonetheless, canker disease has been a hindrance to their production. Phytophthora palmivora is the oomycete responsible for this disease and also the causal agents of fruit rot and stem canker of cocoa, rubber, citrus and jackfruit. With the excessive usage of chemical fungicides. P. palmivora might develop resistance to fungicide and a biocontrol agent can be the alternative way to control it. Hence, the main aims of this study have included isolation, identification of P. palmivora and Bacillus spp as well as identifying the potential Bacillus spp which had the effective suppression against P. palmivora. Throughout this study, the information of Phytophthora palmivora and Bacillus spp are integrated from various electronic databases such as Google scholar, Springer, Science Direct, PubMed, Web of science or others published papers by Ph.D. and M.Sc. dissertations using various keywords. Based on the literature, P. palmivora oomycete could be easily isolated from soil and infected plant parts. The distinctive characteristics of this oomycete have shown papillated and caducous sporangia with a wide range of shapes (ovoid, limoniform, obpyriform, ellipsoid), length, breadth, pedicle length and a consistent length-to-breath ratio (1.6 or 1.62). The chlamydospores were globose with different sizes. Reviews of literature have yielded that six different Bacillus spp have shown promising antagonistic potential against P. palmivora with dual culture tests ranging from 57.77± 2.4 – 100 %. Although the Bacillus spp had been isolated from different sources and crops, they were all targeted to inhibit the P. palmivora. These Bacillus spp have been identified morphologically, biochemically and molecularly as Bacillus amyloliquefaciens, B. velezensis, B. subtilis, B. pumilus, B. altitudinis and B. thuringiensis. The antagonistic mechanisms for these Bacillus spp were further discussed throughout this study.