Time course expression studies during Musa - Pratylenchus coffeae interaction

Abstract

Understanding of molecular mechanisms underlying host-nematode interactions is of primary importance in devising strategies to control nematode. Cultivars with differential reactions to nematode and the optimum time of sampling are the important criteria to study the host-nematode interactions. Based on the investigation on rate of P. coffeae population buildup in the roots, root lesion index, root weight and percentage of healthy root, Karthobiumtham and Nendran were identified as the most resistant and susceptible cultivars respectively among the ten cultivars used in this study. The phenol-metabolizing enzymes, viz., peroxidase and polyphenol oxidase as well as total phenols content and pathogenesis related protein, viz., β-1,3-glucanse were assessed in the roots of P. coffeae inoculated resistant and susceptible banana cultivars. The activities of peroxidase, β-1, 3-glucanase and content of total phenol were higher in the roots of uninoculated resistant cultivar than susceptible one. In post-inoculation stage, a steady increase in enzymes activities was noticed from 2 Days After Inoculation (DAI) onwards with maximum activity on 6 DAI for peroxidase and polyphenol oxidase, 4 DAI for total phenols content and 8 DAI for β-1,3 glucanase. Except total phenols content, the level of enzyme activities was higher even up to 12 DAI than the uninoculated control plants of both cultivars. The PPO activity was again reconfirmed by estimating the time course expression of PPO transcript level. Based on the time course studies on enzyme assays and mRNA level the present study suggested that the samples should be collected within 8 DAI of nematode for understanding the molecular mechanism of Musa-nematode interaction.