Polyamines induced nematode stress tolerance in Solanum lycopersicum through altered physico-chemical attributes

Root-knot nematodes are one of the important phytoparasites that adversely affect the growth and development in plants, thus affecting its productivity. Various chemical nematicides are available commercially, having adverse effect on the environment and non-target organisms. So, it becomes necessary to explore some eco-friendly strategies to manage these parasites. Polyamines recognised as potential phytohormone, enhance the plant survival during stressful conditions. Thus, present study was undertaken to evaluate the stress protective properties of two polyamines in tomato seedlings under nematode stress. Uniform sized tomato (cv. Pusa Ruby) seeds were sterilized and treated with different concentrations (0.5, 0.7 and 0.9 mM) of two polyamines i.e. putrescine and spermine. Seeds are allowed to germinate in in-vitro conditions and subjected to nematode inoculation with second stage juveniles of Meloidogyne incognita @5J₂s per seedlings after germination. Various morphological and biochemical parameters were analysed after one day of nematode inoculation. Nematode invasion alters the morphological and biochemical parameters whereas polyamines treatment restores them to control level. Significant decrease in specific activities of antioxidative enzymes viz: superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase, glutathione peroxidase, polyphenol peroxidase, and pyrogallol peroxidase was observed in polyamines treated seedlings except guaiacol peroxidase and phenylalanine lyase with maximum activity change by spermine application comparing with nematode inoculated seedlings. Chlorophyll content also increases significantly with spermine treatment. Non-enzymatic antioxidants analysis also revealed the anti-stress properties of polyamines as the total phenolic, ascorbic acid content significantly increases whereas decreased glutathione content was observed with polyamine application. Results obtained from confocal microscopy also revealed the inhibition of reduced glutathione and H₂O₂ content in polyamine treated seedlings indicated by weak intensity of fluorescence when compared with nematode inoculated seedlings with lower intensity in spermine applied seedlings.