Bacillus amyloliquefaciens induced systemic resistance against bacterial pustule pathogen with increased phenols, phenylalanine ammonia lyase, peroxidases and 1,3-β-glucanases in soybean plants

Bacillus amyloliquefaciens strain KPS46 has been previously reported to promote plant growth and protect soybean plants from multiple diseases including bacterial pustule caused by Xanthomonas axonopodis pv. glycines . Greenhouse assays were evaluated for its efficient induction of defense-related enzymes in tested plants. Soybean seeds treated with strain KPS46 at sowing and 14 days later challenged the seedlings with bacterial pustule pathogen had few necrotic lesions and reduced disease severity as compared with soybean plants not bacterized with KPS46. The increase in production of total phenol, phenylalanine ammonia lyase, peroxidases and 1,3-β-glucanases were expressed at higher levels in treatment with KPS46 challenge inoculated with the pathogen as compared with the diseased and control plants. Almost defense-related enzymes detected were found to accumulate in soybean leaf tissues of the co-inoculation at one day and reached maximum at 4th day after pathogen challenge, respectively. The pathogen inoculation alone however, started the accumulation at the 3rd day and drastically decreased at 4th day. These produces appear to be one mechanism of biological control by strain KPS46 and may play a role in plant defense against pathogen infection

In vitro inhibition of pathogenic Verticillium dahliae, causal agent of potato wilt disease in China by Trichoderma isolates

Twenty (20) of Verticillium dahliae were isolated from wilted potato specimens collected from six districts in Guizhou, China. All the isolates were evaluated for pathogenicity on two potato cultivars, Favorita (susceptible) and Hui-2 (resistant) using the root dip inoculation (RDI) and microsclerotia inoculation (MI). All of the V. dahliae isolates appeared to be pathogenic on both cultivars but VGZ-HZ-4 isolate gave the highest wilt incidence comparing to the others, seconded by VGZ-SC-1 and VGZ-XW-1. Combined analysis of wilt incidence resulting from using two inoculation methods for VGZ-HZ-4 and VGZ-XW-1 isolates on the two potato cultivars showed that the MI gave a higher wilt incidence than that of the RDI and cultivar Favorita had a higher wilt incidence than that of Hui-2. These two V. dahliae isolates were further used as representative isolates for mycelial inhibition (MyI) test with 33 Trichoderma isolates under a dual culture condition on potato dextrose agar plate. The 33 Trichoderma isolates consisting of 21 isolates isolated from potato soils from seven districts of Guizhou, 11 isolates from single spore isolates of the TGZ-150 isolate preserved at Guizhou Institute of Plant Protection (GZIPP) and one isolate TGZ-OLD-81 also preserved at the GZIPP. Most of the single spore isolates and TGZ-SC-4 were found to have higher MyI efficiency than that of the rest. The results indicate that the Trichoderma isolates in this study have initial modes of action of biological control to protect potato crop against V. dahlia.Keywords: Trichoderma, potato wilt disease, growth inhibition, Verticillium dahliae, antagonistic fungi.African Journal of Biotechnology, Vol 13(31) 3402-341

Drought response of rice in Northeastern Thailand assessed via fourier transform infrared spectroscopy

Drought is a major constraint in many rainfed areas and affects rice yield. We aimed to characterize the physiological changes in rice in response to drought using Fourier transform infrared (FTIR) spectroscopy. Eighty rice landrace seedlings were subjected to drought in the greenhouse using a PEG 6000. Physiological parameters, including total chlorophyll content, relative water content, electrolyte leakage, and biochemical changes were evaluated. Based on the FTIR results, the landraces were divided into three main groups: tolerant, moderately tolerant, and susceptible. Principal component analysis revealed spectral differences between the control and drought stress treatment groups. Lipid, pectin, and lignin content increased after drought stress. The biochemical components of plants at different drought tolerance levels were also compared. The lipid (CH2 and CH3), lignin (C=C), pectin (C=O), and protein (C=O, N–H) contents were the highest in the drought-tolerant cultivars, followed by the moderately tolerant and susceptible cultivars, respectively. Cultivar 17 and 49 were the most tolerant, and the functional groups were identified and characterized using FTIR. Overall, these results will be useful in selecting parental cultivars for rice breeding programs