Exploration of biochemical basis of resistance against root knot nematode in wild bitter gourd, Momordica balsamina

Abstract

In the present work, biochemical indicators of host resistance in Momordica spp. against M. incognita were studied. A set of six lines comprising of two resistant Momordica balsamina lines, two moderately susceptible M. charantia lines and two susceptible M. charantia lines were taken. Post nematode inoculation changes in terms of change in levels of total phenols, flavonols, orthodihydroxy phenols and activity of four defence related enzymes, viz. phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), peroxidase (PO) and tyrosine ammonia lyase (TAL) were analysed in these genotypes representing different levels of resistance. The lignin content of resistant and susceptible genotypes was also estimated and its effect on root knot nematode larval penetration was studied. A trend of elevated levels of phenolic compounds and activity of enzymes was recorded in all the three sets of genotypes. Resistant lines showed significantly higher rate of increase in all the biochemical parameters followed by the moderately resistant and susceptible genotypes. The lignin content was higher in the roots of resistant genotyes and there was a decrease in nematode penetration in roots with increase in lignin content of the genotypes. The present study demonstrate the active role of the phenolic compounds, defence enzymes and lignins for impating resistance and hence their role as potenial biochemical markers for screening against M. incognita.