抗、感大豆品种对尖镰孢根腐病菌侵染及毒素的反应

Response of resistant and susceptible soybean varieties to toxins and invasion of Fusarium oxysporum causing soybean root rot

为了进一步明确大豆抗感品种对根腐尖镰孢的抗病机制,通过透射电镜和形态观察分析了尖镰孢(M38)侵染及产生的毒素对抗感大豆品种的影响。研究表明大豆幼苗胚根经粗毒素处理后,抗病品种‘东农56’幼苗胚根生长没有显著差别,但显著抑制了感病品种‘黑农53’胚根的伸长和侧根的生长;尖镰孢毒素高浓度和低浓度(V粗毒素∶V无菌水=1∶0和1∶15)对抗感品种的致萎能力无显著差异,高浓度处理平均萎蔫指数为100,低浓度处理为17.9~18.1左右;但中等浓度(V粗毒素∶V无菌水=1∶1,1∶5,1∶10)对于感病品种的致萎作用更大;同时,发现尖镰孢侵染感病大豆品种根内侵染量要明显多于抗病品种,且感病品种组织中菌丝的直径明显大于抗病品种,都出现很明显的质壁分离和细胞壁加厚的现象。

In order to further clarify the resistance mechanisms of resistant and susceptible soybean varieties against Fusarium oxysporum causing soybean root rot,the toxic and invasive effects of F.oxysporum were analyzed by using TEM and toxins of F.oxysporum.The results showed that there were no significant differences between treatment and control of the resistant soybean variety ‘Dongnong 56＇with the soybean seedling roots immersed in the toxin solution of F.oxysporum.It was obvious that radicle elongation and lateral root growth of the susceptible variety‘Heinong 53＇were inhibited.At the same time,the wilting ability of high（original fluid of crude toxin）and low（Vcrude toxin∶Vsterile water=1∶15）concentrations of toxins on resistant and susceptible varieties was no obvious differences,with an average wilting index of 100 and 18,respectively.However,it could cause more serious wilt in susceptible varieties than resistant varieties at the moderate concentration of toxins from F.oxysporum（Vcrude toxin∶Vsterile water=1∶1,1∶5 and1∶10）.Observing the soybean roots after inoculation by TEM,we found that the amount and diameter of fungal mycelia of the susceptible variety ‘Heinong 53＇was thicker than those of the resistant variety ‘Dongnong 56＇,and the two varieties both had obvious plasmolysis and cell wall thickening.