Defence responses of cucurbitaceous rootstocks and bitter gourd scions against root knot nematode Meloidogyne incognita kofoid and white
*Corresponding author: Tamilselvi N.A, Department of Vegetable Crops, Department of Nematology, Tamil Nadu Agricultural University, Coimbatore-641 003, Tamil Nadu, India, Tel: 91 75 98 608233; E-mail: email@example.com
Pot culture experiments were conducted under in vitro to understand the biochemical changes takes place during nematode attack and to identify resistant rootstocks for grafting with bitter gourd scions. Results revealed that, three genotypes viz., Kumatikai (Citrulus colocynthis), African horned cucumber (Cucumis metuliferus) and pumpkin (Cucurbita moschata) encompass the lowest value for number of galls per gram root, egg masses per gram root and numbers of females per gram of root and showed resistant reaction followed by two rootstocks viz., Sponge gourd (Luffa cylindrica) and mithipakal (Momordica charantia var. muricata) bare minimum values and are moderately resistant. These resistant reaction yet again confirmed by assessment of defence enzymes viz.,phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenoloxidase (PPO), Acid phosphatase and biochemical components viz., total phenol and ortho dihydroxy phenol (OD phenol). The present study indicates that rapid augmentation of PAL, PO, PPO, acid phosphatase, total phenol and OD phenols activities were noticed in resistant rootstocks viz., C. colocynthis, C. metuliferus and C. moschata and started to increase at 24 hours after inoculation, reached maximum at 96 hours after inoculation and thereafter declined. Similarly, native poly acralamide gel electrophoresis (PAGE) analysis revealed that one to six isoforms of defence enzymes were observed in aforementioned resistant rootstocks whereas fewer isoforms with less intensity were noticed in susceptible rootstocks and bitter gourd scions. These results suggest that the aforementioned resistant rootstocks are potential source for managing root knot nematode menace in bitter gourd by grafting.
Meloidogyne incognita, Resistance, Rootstocks, Bitter gourd, Defence enzymes, Grafting.