摘要：

为了探讨玉米对灰斑病胁迫的生理生化响应,采用田间自然接种法,以2个自交系K365(抗)和K169(感)以及2个杂交种正红431(抗)和正红532(感)为试验材料,研究灰斑病对不同抗性玉米自交系及杂交种叶片光合作用、活性氧含量、抗氧化酶活性以及内源激素含量的影响。灰斑病胁迫导致玉米叶片净光合速率(Pn)、气孔导度(Gs)、胞间CO₂浓度(Ci)和蒸腾速率(Tr)均下降,其中除Ci以外,抗病材料的3项光合指标下降程度未达显著水平,具体为K365的Pn、Gs和Tr分别下降24.41%,25.00%,4.20%,正红431的Pn、Gs和Tr分别下降11.53%,21.43%,0.06%,而感病材料的3项光合指标下降程度达显著水平,具体为K169的Pn、Gs和Tr分别下降59.32%,95.28%,80.18%,正红532的Pn、Gs和Tr分别下降85.39%,69.60%,56.77%;同时灰斑病胁迫可使玉米叶片的过氧化氢(H₂O₂)含量、过氧化物酶(POD)活性、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、水杨酸(SA)含量、茉莉酸(JA)含量均上升,其中抗病材料能激发更高的POD、SOD和CAT活性,维持相对稳定的H₂O₂含量,更合理的调节SA和JA含量,能够保持内源激素的平衡。抗病材料可能通过合理积累SA、JA等信号分子来调控抗氧化系统,使其在感病后期体内仍维持较高水平的防御酶活性来更有效清除多余的H₂O₂,同时调节叶片的内源激素平衡使其适应灰斑病带来的影响,从而增强玉米的抗病性。

关键词: 玉米, 灰斑病, 光合作用, 抗氧化酶, 内源激素

Abstract:

To investigate the physiological and biochemical responses of maize to gray spot stress.Using the natural inoculation method in the field,two inbred lines K365(resistant)and K169(susceptible)and two hybrids Zhenghong 431(resistant)and Zhenghong 532(susceptible)were used as test materials.To study the effects of gray spot disease on leaf photosynthesis,reactive oxygen species content,antioxidant enzyme activity and endogenous hormone content of different resistant maize inbred lines and hybrids.Gray leaf spot stress led to the decrease of net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci) and transpiration rate (Tr) of maize leaves, except for Ci, the three photosynthetic indexes of resistant materials did not decrease significantly, specifically, Pn, Gs and Tr of K365 decreased by 24.41%,25.00% and 4.20%, respectively. The Pn, Gs and Tr of positive Zhenghong 431 decreased by 11.53%, 21.43% and 0.06%, respectively, while the three photosynthetic indexes of susceptible material decreased significantly, specifically, Pn, Gs and Tr of K169 decreased 59.32%, 95.28% and 80.18%, respectively. The Pn, Gs and Tr of Zhenghong 532 decreased by 85.39%, 69.60% and 56.77%, respectively;at the same time, the content of hydrogen peroxide (H₂O₂), peroxidase (POD) activity, superoxide dismutase (SOD) activity, catalase (CAT) activity, salicylic acid (SA) content, and jasmonic acid (JA) in maize leaves were increased under leaf gray spot stress, and the resistant materials could stimulate higher POD,SOD and CAT activities,maintaining a relatively stable H₂O₂ content,more reasonable regulation of SA and JA content,could maintain the balance of endogenous hormones.Resistant material may through rational accumulation of SA,JA signaling molecules to regulate antioxidant system,late in the disease still maintain a high level of defense enzymes in the body to more effectively remove excess H₂O₂,at the same time,adjust the blade endogenous hormone balance to make it adapt to the effects of resistant,thus to enhance maize disease resistance.

Key words: Maize, Gray leaf spot, Photosynthesis, Antioxidant enzyme, Endogenous hormone