Rhizobacterial-mediated induction of defense enzymes to enhance the resistance of turmeric (Curcuma longa L) to Pythium aphanidermatum causing rhizome rot |
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Authors: | K Kavitha S Nakkeeran G Chandrasekar |
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Institution: | 1. Oilseeds Research Station, Tamil Nadu Agricultural University , Tindivanam , Tamil Nadu , India kavithagobi@gmail.com;3. Department of Plant Pathology , Centre for Plant Protection Studies, Tamil Nadu Agricultural University Coimbatore , 641 003 , Tamil Nadu , India |
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Abstract: | Rhizobacteria isolated from the rhizosphere soil were evaluated for their ability to control rhizome rot in turmeric (Curcuma longa L). These isolates were characterised as Pseudomonas fluorescens and Bacillus subtilis. Under in vitro condition, two isolates, namely P. chlororaphis (PcPA23) and B. subtilis (BsCBE4), showed maximum inhibition of mycelial growth of Pythium aphanidermatum, were found effective in reducing rhizome rot of turmeric both under greenhouse and field conditions and increased the plant growth and rhizome yield. Both the isolates were further tested for its ability to induce production of defense-related enzymes and chemicals in plants. Increased activities of phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, chitinase and β-1,3-glucanase were observed in PcPA23 and BsCBE4 pre-treated turmeric plants challenged with P. aphanidermatum. Moreover, higher accumulation of phenolics was noticed in plants pre-treated with PcPA23 and BsCBE4 challenged with P. aphanidermatum. Thus, the present study shows that in addition to direct antagonism and plant growth promotion, induction of defense-related enzymes involved in the phenyl propanoid pathway collectively contributed to enhance resistance against invasion of Pythium in turmeric. |
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Keywords: | Pseudomonas chlororaphis Bacillus subtilis Pythium aphanidermatum induced resistance peroxidase polyphenol oxidase chitinase β-1 3-glucanase phenols |
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