玉米抵御玉蜀黍尾孢菌侵入的生理机制
The physiological mechanism of corn against Cercospora zeae-maydis infection

为深入探讨玉米抗灰斑病的机制,以抗/感玉米灰斑病自交系78599-1、OH43HtN和掖478、K12为材料,采用比色皿法和RT-PCR法相结合研究了接种玉蜀黍尾孢菌毒素后玉米叶片中防御酶活性、丙二醛(MDA)含量及防御酶合成相关基因SOD、CAT、APX和GR的表达量.结果显示,接种该病菌毒素后,抗、感材料叶片中防御酶活性均升高,多数在接种7 d时达到峰值,且抗病材料防御酶活性峰值高于感病材料;供试材料叶片中MDA含量均降低,且抗病材料低于感病材料;供试材料叶片中SOD、CAT和GR的表达量均上升,其中CAT的表达量在78599-1、掖478和K12接种5 d时达到峰值,灰度值分别为228.67、161.33和178.00,与其酶活性变化趋势一致;SOD和GR的变化规律与其酶活性变化不一致;APX的表达量仅在OH43HtN中上升,接种7 d后达到峰值.表明抗病材料调控防御酶活性的能力强,防御酶基因的表达与其酶活性变化存在关联性.
In order to investigate the resistant mechanism of corns against gray leaf spot, resistant inbred lines 78599-1, OH43HtN and susceptible inbred lines Ye 478, K12 were selected as experimental materials. The activities of defensive enzymes, the content of malonaldehyde (MAD) and the transcriptional level of resistance-related genes SOD, CAT, APX and GR were measured after the plants were inoculated with Cercospora zeae-maydis toxin by using cuvettes and reverse transcription PCR methods. The enzyme activity in leaves was increased and reached the maximum seven days after inoculation. In addition, the maximum enzyme activity in the resistant inbreds was higher than that in susceptible inbred lines. The content of MDA was also increased after the inoculation with C. zeae-maydis toxin and the MDA content in the resistant inbreds was lower than that in susceptible inbred lines. The SOD, CAT and GR expressions were increased and the APX expression was increased only in the inbred lines OH43HtN. The CAT expression in leaves of 78599-1, Ye 478 and K12 reached the maximum five days after inoculation, and their values were 228.67, 161.33 and 178.00, respectively. There were similar trends between the change in CAT expression and CAT activity in the above-mentioned varieties. There were no similar trends between changes in SOD and GR expression and activities of SOD and GR. These results indicated that the resistant inbred lines had a stranger ability to control enzyme activity and there was a correlation between the gene expression of defensive enzymes and enzyme activity.