The Hypersensitivity Reaction of Tomatoes Resistant to Meloidogyne incognita: Reversal by Cytokinins.
The Hypersensitivity Reaction of Tomatoes Resistant to Meloidogyne incognita: Reversal by Cytokinins.
复制标题
番茄对南方根结线虫具有抗性的超敏反应：细胞分裂素的逆转。
作者：
V. Dropkin;J. Helgeson;C. Upper
以番茄幼苗对南方根结线虫的抗性或敏感性为指标，测定了番茄幼苗对根结线虫的抗性或感受性。在没有外源植物生长调节物质的情况下，约73%的幼虫进入感病植株的根部后生长，没有引起死亡，几乎所有的幼虫都诱导形成了根瘤。在抗性品种的根部，只有4%的幼虫生长，88%的幼虫引起寄主细胞的坏死，只有29%的幼虫产生虫害。外源供应的细胞分裂素使抗性植物的反应转向敏感反应。0.4和0.8微摩尔的外源激动素使55%和57%的线虫生长，使坏死率分别降至32%和31%，并使虫卵形成率分别增加到73%和65%。另外三种细胞分裂素，玉米素，6-(伽马，伽马-二甲基烯丙氨基)嘌呤和6-苄氨基嘌呤产生类似激动素的效果。外源吲哚乙酸、赤霉酸、腺嘌呤、鸟嘌呤、尿嘧啶、胸腺嘧啶、胞苷和6-甲氨基嘌呤均不能增加幼虫的生长率，也不能减少寄主细胞的坏死程度。
Initiation of larval growth, induction of cell necrosis, and gall formation in the host were measured as criteria of resistance or susceptibility of tomato seedlings to the root-knot nematode, Meloidogyne incognita (Kofoid &White) Chitwood. Seedlings grown at 27 C on water agar containing additions were scored 3 or 4 days after infection.In the absence of exogenous plant growth regulatory substances, approximately 73% of larvae that entered roots of susceptible plants showed growth, none induced necrosis and nearly all induced gall formation. In roots of a resistant variety, only 4% of the larvae grew, 88% induced necrosis of host cells, and only 29% induced galls. Exogenously supplied cytokinins shifted the response of the resistant plants toward the susceptible reaction. Exogenous kinetin at 0.4 and 0.8 micromolar allowed 55 and 57% of the nematodes to grow, reduced the incidence of necrosis to 32 and 31%, and increased gall formation to 73 and 65%. Three additional cytokinins, Zeatin, 6-(gamma,gamma-dimethylallylamino)purine, and 6-benzylaminopurine produced effects similar to kinetin. Exogenous indoleacetic acid, gibberellic acid, adenine, guanine, uracil, thymine, cytidine, and 6-methylaminopurine neither increased the percentage of larvae which grew nor decreased the extent of host cell necrosis.