• Journal of Microbiology and Biotechnology
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• v.28 no.9
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• pp.1527-1535
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• 2018

Bacterial strain BAS23 was isolated from rice field soil and identified as Bacillus amyloliquefaciens. Based on dual culture method results, the bacterium BAS23 exhibited potent in vitro inhibitory activity on mycelial growth against a broad range of dirty panicle fungal pathogens of rice (Curvularia lunata, Fusarium semitectum and Helminthosporium oryzae). Cell-free culture of BAS23 displayed a significant effect on germ tube elongation and mycelial growth. The highest dry weight reduction (%) values of C. lunata, H. oryzae and F. semitectum were 92.7%, 75.7%, and 68.9%, respectively. Analysis of electrospray ionization-mass spectrometry (ESI-MS) and $^1H$ nuclear magnetic resonance (NMR) spectroscopy revealed that the lipopeptides were iturin A with a C14 side chain (C14 iturinic acid), and a C15 side chain (C15 iturinic acid), which were produced by BAS23 when it was cultured in nutrient broth (NB) for 72 h at $30^{\circ}C$. BAS23, the efficient antagonistic bacterium, also possessed in vitro multiple traits for plant growth promotion and improved rice seedling growth. The results indicated that BAS23 represents a useful option either for biocontrol or as a plant growth-promoting agent.

• Korean journal of applied entomology
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• v.25 no.2 s.67
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• pp.107-112
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• 1986

Species of pathogens and insects associated with grain discoloration in the Philippines were indentified. Leptocorisa oratorios was the most dominant insect species causing discoloration. Pathogenicity tests of fungal organisms isolated from discolored grains showed that Drechslera oryzae, Curvularia lunata, Trichoconiella padwickii, Sarocladium oryzae, Alternaria tenuis, and Fusarium solani were the common pathogens responsible for 'dirty panicle' disease of rice. Discoloration incidence was higher on treatment when both pests were present than when they occurred singly. The discoloration severity was attributed to the pathogens whereas rice bug caused a high decrease in grain weight and unfilled grains. Rice bug feeding on grains enhances the infection caused by the pathogen. Due to this, the quantity and quality of grains produced were affected, resulting in yield reduction.