Authors:L. Rajendran, R. Akila, G. Karthikeyan, T. Raguchander and R. Samiyappan
Endophytic bacteria Bacillus subtilis (EPC 5) was isolated and tested in vitro along with Pseudomonas fluorescens (Pf1) and the fungus Trichoderma viride (Tv1) against Ganoderma lucidum (Leys) Karst, the causal agent of basal stem rot on coconut palm. The endophytic bacterial strains namely EPC 5 and EPC 8 showed higher vigor index (germination percentage, root and shoot length) and more inhibition against G. lucidum over un-inoculated control. These strains were confirmed as Bacillus subtilis by biochemical tests, cloning and sequencing of internal transcribed spacer (ITS) region. The Bacillus subtilis (EPC 5) along with Pseudomonas fluorescens (Pf1) and Trichoderma viride (Tv1) has been tried as bioconsortia against basal stem rot disease under greenhouse conditions. The soil application of bioconsortia enriched with farm yard manure (FYM) enhanced the coconut saplings growth under greenhouse conditions and showed higher induction of defense related enzymes like peroxidase, polyphenol oxidase, phenylalanine ammonia lyase and phenols when challenged with pathogen.
quantified following the assay of A ssis and co-workers (2001) . Both parameters were expressed as milligrams pergram of FW (fresh weight). 1.5 Gene expression of defense-relatedenzymes and PR genes The total RNA extraction from frozen tissue samples was
Authors:A. Kamalakannan, L. Mohan, K. Kavitha, S. Harish, R. Radjacommare, S. Nakkeeran, V. K. Parthiban, R. Karuppiah and T. Angayarkanni
Five isolates of Trichoderma viride, Pseudomonas fluorescens and four isolates of Bacillus subtilis were evaluated for their ability to control Rhizoctonia solani, the causal agent of stem and stolon rot of peppermint (Mentha piperita Lin.). Of the various isolates of T. viride, P. fluorescens and B. subtilis tested, TVUV10, PFMMP and BSG3 showed the maximum inhibition of mycelial growth of R. solani. Among these isolates, P. fluorescens, PFMMP recorded the highest inhibition zone against R. solani in vitro and was very effective in reducing disease incidence in greenhouse condition. The effective isolates were evaluated for their ability to induce defense related enzymes and chemicals in plants. Increased activity of phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenoloxidase (PPO) and total phenolics were recorded in the biocontrol agents pretreated peppermint plants challenged with R. solani. P. fluorescens isolate PFMMP recorded early and increased synthesis of all defense related enzymes and total phenol. Thus, the present study shows that application of biocontrol agents; induce defense related enzymes involved in phenyl propanoid pathway in addition to direct antagonism which collectively contribute for enhanced resistance against invasion of R. solani in M. piperita.
strain KPS46 has been previously reported to promote plant growth and protect soybean plants from multiple diseases including bacterial pustule caused by
. 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.
Authors:P. Zhang, M. Zhou, X. Zhang, Y. Huo and H. Ma
Crown rot caused by Fusarium pathogens is one of the most economically destructive diseases of wheat. The objective of this study was to investigate defense-related enzyme responses in wheat seedlings infected with Fusarium graminearum. Three wheat varieties were employed to the experiment. Physiological analysis of varieties indicated that defensive-related enzymes were induced by F. graminearum infection. The superoxide dismutase and peroxidase activities increased dramatically and the phenylalanine ammonia-lyase activity was stimulated to a higher level in resistant variety Hongyouzi than in susceptible variety Wo0102. However, the chitinase activity was higher in susceptible variety Wo0102 than in Hongyouzi after infection. These results suggest that the defense enzymes could be stimulated in wheat seedlings by Fusarium infection.
Authors:Waheed Akram, Asrar Mahboob and Asmat Ali Javed
The research work was performed to investigate the potential of Bacillus thuringiensis strain 199 to induce systemic resistance in tomato against Fusarium wilt. Roots of two-week-old seedlings of tomato plants were primed with bacterial strain. After 10 days of transplantation, some pots of tomato seedlings were provided with inoculum of Fusarium oxysporum lycopersici according to experimental design to induce disease. After 15 days of incubation period, plants challenged with F. oxysporum lycopersici alone were having obvious symptoms of Fusarium wilt. Plants that were treated with B. thuringiensis 199 + F. oxysporum lycopersici were having significant reduction of disease severity. Quantity of total phenolics increased 1.7-fold in bacterial-treated plants as compared to nontreated. Likewise, in case of defense-related enzymes, a significant increase of 1.3-, 1.8-, and 1.4-fold in polyphenol oxidase (PPO), phenyl ammonia lyase (PAL), and peroxidase (PO) was observed in comparison with untreated control. These results, hence, prove the potential of this bacterial strain for use as plant protection agent.
. Physiol. and Biochem. , 79 , 176 – 179 .
Haller , H. , Jadesha , G. and Prakasa , V. ( 2012 ): Impact of fungicides and botanicals on the induction of defenserelatedenzymes in sugar beet plant against C. beticola . Green Farm. , 3 , 720
Yamunarani , K. , Jaganathan , R. , Bhaskaran , R. , Govindaraju , P. and Velazhahan R. ( 2004 ): Induction of early blight resistance in tomato by Quercus infectoria gall extract in association with accumulation of phenolics and defense-related