不同蚜虫密度胁迫对抗感玉米幼苗生理物质的影响

以两种不同抗蚜玉米(Zea mays L.)品种郑单958(抗蚜)、蠡玉16(感蚜)为研究对象,研究了其在三叶期受到不同密度(0、10、20、40、80头·株^-1)玉米蚜(Rhopalosiphum maidis Fitch)刺吸胁迫后,丙二醛(MDA)、可溶性糖、叶绿素(Chl)、可溶性蛋白含量和保护酶活性等的动态变化。结果表明,在不同密度蚜虫刺吸胁迫过程中,郑单958和蠡玉16的可溶性糖含量随蚜虫密度的增加而升高,且郑单958的增长幅度小于蠡玉16;两个品种幼苗Chl含量则是随着蚜虫密度升高而呈现下降趋势,蠡玉16下降变化率明显大于郑单958;可溶性蛋白含量变化则与MDA含量变化趋势基本相同且均呈现出上升趋势;郑单958的丙二醛、可溶性蛋白含量的变化百分率均低于蠡玉16。因此,叶绿素含量与蚜虫密度之间呈负相关关系;而可溶性糖含量、可溶性蛋白含量、MDA含量与蚜虫密度之间呈正相关。叶绿素含量变化率可以作为抗蚜性的一个指标,而可溶性糖含量、可溶性蛋白含量、MDA含量与玉米抗蚜性呈负相关。超氧化物歧化酶(SOD)、过氧化物酶(POD)以及过氧化氢酶(CAT)的活性随蚜虫密度的增加呈现先上升后下降的趋势,但与对照组相比,总体上酶活性都是增加的;而多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)的活性随蚜虫密度的增加呈现上升的趋势。抗感蚜玉米品种苗期的酶活性与蚜虫的密度相关,且PPO、PAL起着主要保护作用;而SOD、POD、CAT只有在蚜虫密度较低的状态下才能发挥酶的保护作用。

Effects of different aphid density stress on physiological substances in resistant and susceptible maize varieties at seedling stage

Two different aphid resistant maize (Zea mays L.) varieties, Zhengdan 958(resistant variety) and Liyu 16(susceptible variety),were used in this study, and the dynamic changes of malondialdehyde (MDA), soluble sugar, chlorophyll (Chl), soluble protein and five protective enzymes were measured after different density of aphids (0,10,20,40,80 heads per plant) suction stress in three leaf stages. The results showed that: in the different density of aphids sucking stress, the soluble sugar content of Zhengdan 958 and Liyu 16 increased with the density of aphids, and the growth rate of Zhengdan 958 was less than Liyu 16. Chlorophyll content of two varieties decreased with aphid density increased, and the decrease rate of Liyu 16 was higher than that of Zhengdan 958. The change of soluble protein content was almost the same as the content of malondialdehyde (MDA), showing an upward trend, but the percentage change of MDA, soluble protein content in Zhengdan 958 was lower than that of Liyu 16.Therefore, there was a negative correlation between chlorophyll content and aphid density, while soluble sugar content, soluble protein and malondialdehyde (MDA) content were positively correlated with aphid density. The chlorophyll content change rate could be used as an index of aphid resistance, but the soluble sugar content, soluble protein and malondialdehyde (MDA) content were negatively correlated with the aphid resistance of maize. The activities of superoxide dismutase(SOD), peroxidase(PPO) and catalase(CAT) in Zhengdan 958 and Liyu 16 increased first and then decreased with the increase of aphid density. But the activities of five protective enzymes were higher than the control group; while the activity of polyphenol oxidase(PPO) and phenylalanine ammonia lyase(PAL) showed upward trend with the increase of aphid density. According to the results, it can be seen that the enzyme activity was related to the density of aphid at maize seedling stage. PPO and PAL play a leading role in the protective enzymes of maize, and SOD, POD and CAT play a protective role in lower aphid density.