Catalase inhibitors, such as salicylic acid (SA), isonicotinic acid (INA) and 3-amino-triazole (3-AT) act in plants as defense elicitors. Overnight incubation with these chemicals of susceptible tomato seedling before inoculation actually lowered the reproduction index of Meloidogyne incognita, calculated as number of eggs per gram root fresh weight. Surprisingly, only SA did not have any apparent effect on RKN reproduction. When catalase was assayed in extracts of roots treated with SA, its activity even enhanced with respect to controls, comparably with roots 24 h after inoculation with RKN. The failure to inhibit nematode development by SA may be associated with a putative insensitivity of root catalase to this chemical. Chemicals such as the herbicide paraquat (PQ) or diethyldithiocarbamic acid (DIECA) raise the cellular level of superoxides radicals (O2-) the first favoring a one-electron reduction of molecular oxygen, the second by inhibiting superoxide dismutase (SOD), which neutralizes such radicals. Treatment with these two chemicals at very low concentrations decreased RKN reproduction on tomato without affecting plant growth and health. Surely, calcium uptake by plant cells is one of the first signals determining biochemical reactions against invading organisms or abiotic stresses. Jasmonic acid (JA) is the mediator of wound-response and acts as a calcium ion ionophore in plant cell membranes. Treatment of tomato seedlings with either jasmonic acid or a synthetic calcium ionophore (calcimycin, A23187) did not affect RKN reproduction, thus confirming that wound-response may occur in compatible Meloidogyne-tomato interaction but it is not sufficient to inhibit nematode feeding site formation. Interestingly, lanthanium ions, which compete with calcium ions for transport into the cells, highly increase root infestation. Furthermore, the key role of calcium intake as mediator of defense responses by the plant is indicated by the complete susceptibility of normally resistant tomato seedlings treated with lanthanium ions before inoculation with M. incognita.
Effect of plant defence elicitors and cations on reproduction of RKN on tomato.
Molinari S
2002
Abstract
Catalase inhibitors, such as salicylic acid (SA), isonicotinic acid (INA) and 3-amino-triazole (3-AT) act in plants as defense elicitors. Overnight incubation with these chemicals of susceptible tomato seedling before inoculation actually lowered the reproduction index of Meloidogyne incognita, calculated as number of eggs per gram root fresh weight. Surprisingly, only SA did not have any apparent effect on RKN reproduction. When catalase was assayed in extracts of roots treated with SA, its activity even enhanced with respect to controls, comparably with roots 24 h after inoculation with RKN. The failure to inhibit nematode development by SA may be associated with a putative insensitivity of root catalase to this chemical. Chemicals such as the herbicide paraquat (PQ) or diethyldithiocarbamic acid (DIECA) raise the cellular level of superoxides radicals (O2-) the first favoring a one-electron reduction of molecular oxygen, the second by inhibiting superoxide dismutase (SOD), which neutralizes such radicals. Treatment with these two chemicals at very low concentrations decreased RKN reproduction on tomato without affecting plant growth and health. Surely, calcium uptake by plant cells is one of the first signals determining biochemical reactions against invading organisms or abiotic stresses. Jasmonic acid (JA) is the mediator of wound-response and acts as a calcium ion ionophore in plant cell membranes. Treatment of tomato seedlings with either jasmonic acid or a synthetic calcium ionophore (calcimycin, A23187) did not affect RKN reproduction, thus confirming that wound-response may occur in compatible Meloidogyne-tomato interaction but it is not sufficient to inhibit nematode feeding site formation. Interestingly, lanthanium ions, which compete with calcium ions for transport into the cells, highly increase root infestation. Furthermore, the key role of calcium intake as mediator of defense responses by the plant is indicated by the complete susceptibility of normally resistant tomato seedlings treated with lanthanium ions before inoculation with M. incognita.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
