Effect Of Marco-nutrition On Development Of Giant Cell By Root-knot Nematode

Root-knot nematodes developed original and complex mechanisms of parasitism leading to the re-differentiation of root cells into permanent feeding sites called"giant cells". Growth and reproduction of nematode depend on the establishment of these giant cells. The development of giant cells induced by root-knot nematode Meloidogyne spp. in tomato roots has been followed under different growth conditions, and measurement for tomato's height, fresh weight of root system, root-knot number, size of giant cell, the number of J2 penetrated into the tomato within 24h after inoculation have been taken. Observations on paraffine section of the root knot were conducted. The results demonstrated that different cultivate conditions have different roles on the development of giant cells. The tomato's height, fresh weight of root system, root-knot number, size of giant cell, the number of J2 penetrated into the tomato within 24h did not have difference among treatments of normal nutrition, potassium-starved stress and inhibitor of potassium channels. The duration of root-knot nematode was not changed on potassium-starved stress and inhibitor of potassium channels. Compared with normal nutrition, the giant cells formed under potassium-starved stress and inhibitor of potassium channels have thicker cell wall, denser cytoplasm and have granule of carbohydrate. The tomato's height, fresh weight of root system, root knot number, size of giant cells, the J2 penetrated into the tomato within 24h after inoculate do have difference between normal nutrition, nitrogen-starved stress and phosphorus-starved stress. Also, the duration of root-knot nematodes are longer on nitrogen-starved stress and phosphorus-starved stress. We didn't observe full-grown female nematodes and the formation of ovum in their bodies. The giant cells formed under these two nutritions have thinner cell wall, less nucleolus and more cell-wall ingrowths. The reason maybe that nitrogen and phosphorus play an important role in synthesize of protein and nucleic acid. These nutrition stresses made tomato growth worse, so root-knot nematode can not absorb enough nutrition.Different concentration of Methyl jasmonate (MeJA) were applied as foliar spray to tomato, we discovered that when sprayed 0.5 mmol /L MeJA, the giant cells were the same with the control. As spraying 5 mmol /L MeJA, the galls were difficult to form, and the development of giant cell was slower than that of the control.