Temporal and spatial changes in phenolic compounds in response to Fusarium wilt in chickpea and pigeonpea.

Plant phenolic compounds are known to play an important role in innate plant defense and are reported to show temporal and spatial changes in response to abiotic and biotic stress including invading pathogens. In the present study, spatial and temporal variations in phenolic compounds in response to infection by wilt pathogen, Fusarium oxysporum f. sp. ciceri (Foc) and Fusarium udum (Fud) were studied in wilt resistant and wilt susceptible cultivars of chickpea (Cicer arietinum L.) and pigeonpea (Cajanus cajan L. Millspaugh) (i) before the onset of wilt infection (S1 stage; 7 Days after sowing (DAS)), (ii) after the onset of wilt infection (S2 stage; 15 DAS) and (iii) at severe disease stage (S3 stage; 30 DAS), respectively and analyzed for association of total phenol with disease reaction. Under un—inoculated condition, maximum phenol content (21.8 mg gdw—1) was found in wilt resistant cultivars and minimum (16.5 mg gdw—1) in susceptible lines of chickpea. Wilt resistant cultivars of chickpea showed two fold increase in total phenolic content at the onset of infection. In case of pigeonpea, roots of resistant cultivars showed 2.27 fold increase in phenolics, but the increase was marginal in susceptible cultivars. In the present study, interaction between Fusarium and host plants was found to enhance defense responses against wilt disease in resistant cultivars of chickpea and pigeonpea.