Abstract
Brown rot or bacterial wilt of potato caused by Ralstonia solanacearum, is an economically important disease. Potato, cv. Nicola, was found to be relatively highly resistant to the infection with R. solanacearum and showed 15.12% wilt disease index, meantime, cv. Kara showed intermediate resistance with 37.40% disease index while, cv. Spunta was susceptible and showed 80.33% disease index. The role of defense-related enzymes in imparting resistance in potato against R. solanacearum was investigated by quantifying enzymes activity and gene expression of three defense- related enzymes, peroxidase, polyphenol oxidase and catalase. Peroxidase showed maximum activity 0.488 min-1·g-1 early at 12 h after pathogen inoculation in the cv. Nicola, whereas in susceptible cultivar Spunta showed lower activity of maximum 0.226 min-1·g-1 later at 48 h after inoculation. While, the moderately resistant cultivar Kara showed intermediate activity for the peak and its time. Meanwhile, polyphenol oxidase showed similar trends to that of peroxidase. On the contrary, catalase showed the highest activity values in the susceptible, cv. Spunta, while, in relatively highly resistant (cv. Nicola) and the moderately resistant (cv. Kara) showed lower values of activity and up to 96 h after inoculation. Meanwhile, gene expression of related enzymes the RT-PCR was used. At zero time, the relatively highly resistant potato cultivar, Nicola, showed the highest values of gene expression for both Peroxidase (POD) and Poly Phenol Oxidase (PPO). While, the susceptible potato cultivar, Spunta showed the lowest values. On the contrary, Catalase (CAT) gene expression was the highest in the susceptible, cv. Spunta, and was the lowest in the relatively highly resistant, cv. Nicola, while, was of intermediate values in the intermediate resistance, cv. Kara. Results show that peroxidase and polyphenol oxidase activities can be used as biochemical markers to reveal the resistance and susceptibility nature of potato cultivars against bacterial wilt disease of potato caused by R. solanacaerum.
Highlights
Potato (Solanum tuberosum L.) is one of the most consumed crops in the world with global production of approximately 367,753,014 tons, produced from approximately 19,454,997 hectares [1] around the world
Brown rot or bacterial wilt of potato caused by Ralstonia solanacearum constitutes a threat to potato cultivation in Egypt and in all tropical agriculture [2]
Real Time PCR (RT-PCR) has become an extensively applied technique in molecular plant pathology and it has been extensively used for quantification of different enzymes gene expression activities [8]
Summary
Potato (Solanum tuberosum L.) is one of the most consumed crops in the world with global production of approximately 367,753,014 tons, produced from approximately 19,454,997 hectares [1] around the world Meantime, it is considered one of the most important vegetable crops in Egypt. Disease resistance in plants is associated with activation of a wide array of defense responses that slow down or halt infection at certain stages of the host-pathogen interaction. These defense mechanisms include preexisting physical and chemical barriers that interfere with pathogen establishment. And elevated levels of expressions of various defense enzymes are an important feature including peroxidase (POD), polyphenol oxidase (PPO) and catalase (CAT) during host pathogen interactions. Aims of the present study were to: 1) Investigate the reaction of different potato cultivars to infection with R. solanacearum. 2) Investigate the potential of peroxidase (POD) and catalase (CAT) enzymes activity in relation to potato resistance to R. solanacearum. 3) Quantifying the gene expression levels of peroxidase, polyphenol oxidase and catalase enzymes using Real Time PCR
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