大豆疫霉根腐病菌毒素对抗感不同大豆品种叶片超微结构的影响

Effect of Pathotoxin Produced from Phytophthora sojae on the Ultrastructure of Leaves of Soybean Varieties with Different Resistance

毒素是大豆疫霉根腐病的主要致病因子之一,而毒素对大豆细胞超微结构的影响还未见报道,用不同浓度的毒素处理抗感不同大豆品种的叶片,为揭示毒素在细胞水平的致病机理及寄主抗毒素的机理奠定一定的理论基础。结果表明,较高浓度大豆疫霉根腐病菌毒素(稀释50倍,浓度为0.1794mg·mL-1)处理抗感不同大豆品种的离体叶片后,不论是抗病品种还是感病品种叶片细胞内部结构都遭到了明显的破坏。适宜浓度的毒素(稀释100倍,浓度为0.0897mg·mL-1)处理抗感品种离体叶片后,抗病品种细胞内部结构基本上比较完整,而感病品种叶片细胞内部结构已经发生了较大的变化,叶绿体嵴变形,基粒片层已经基本消失,叶绿体膜已经解体,线粒体空泡化严重。说明只有在适宜浓度毒素处理下,才能在细胞超微结构上区分出抗感品种在抗性上的差异。

Pathotoxin is one of the main pathogenic factors of Phytophthora sojae, which could destroy the cell structure of soybean. To investigate the effect of pathotoxin on cell ultrastructure of soybean, two soybean varieties of Suinong 10 （ resistant to Phytophthora sojae） and Hefeng 25 （ susceptible to Phytophthora sojae） were used in this experiment. The excised leaves of the two soybean varieties were dipped into the pathotoxin solution with different concentration（ one is the pathotoxin solution of relatively high concentration,0. 1794 mg · mL^-1 ;the other is pathotoxin solution of optimal concentration ,0. 0897 mg · mL ^-1 ） ,and fixed in the fixation solution after 48 h and 72 h. The ultrastructures of leaves of Suinong 10 and Hefeng 25 were all seriously destroyed after treated with relatively high concentration of pathotoxin solution. The ultrastructure of leaves of resistant soybean Suinong 10 was almost intact after treated with optimal concentration of pathotoxin, but the cell structure of susceptible variety Hefeng 25 changed a lot. The chloroplast grana nearly disappeared, chondriosome appeared vacuolus, and chondriosome envelope disaggregated. The results showed that only optimal concentration of pathotoxin solution could distinguish the difference in cell structure between soybean varieties resistant or susceptible to Phytophthora sojae.