20 种杨树抗腐烂病筛选及抗感品种生理差异OA

Poplar canker is one of the major branch and stem diseases caused by Cytospora chrysosperma(Pers.)Fr.,which is highly destructive and widely distributed.To investigate the differences in resistance to poplar canker among different vari-eties,20 poplar varieties commonly used in Northeast China were used as materials.Through resistance evaluation trials of poplar canker,resistant and susceptible varieties were screened.Furthermore,changes in the contents of oxidative stress-related physiological indices(superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),and malondialdehyde(MDA)),defense enzyme activities(polyphenol oxidase(PPO)and phenylalanine ammonia-lyase(PAL)),and sec-ondary metabolites(total flavonoids,total phenols,and lignin)were analyzed at 0,1,2,3,and 4 days after inoculation in resistant and susceptible varieties.The results showed that among the 20 poplar varieties,Populus×berolinensis was the most resistant,while'Zhongxiong No.4'was the most susceptible.The disease incidence of'Zhongxiong No.4'was 3.62,2.28,and 1.22 times that of P.×berolinensis at 10,20,and 30 days,respectively.Compared with the susceptible variety'Zhongxiong No.4',the resistant variety P.×berolinensis exhibited the following characteristics:SOD activity in both varieties increased significantly on the first day after inoculation,and that in P.×berolinensis was 30.04%higher than that in'Zhongxiong No.4'.The peak POD activity in P.×berolinensis appeared 1 day earlier and was 43.11%higher than that in'Zhongxiong No.4'.CAT activity in both varieties increased significantly on the second day after inocula-tion,and that in P.×berolinensis was 7.98%higher.MDA content in both varieties increased significantly on the first day after inoculation,but that in P.×berolinensis was 22.74%lower.The peak PPO activity in P.×berolinensis appeared 1 day earlier and was 23.79%higher.PAL activity in both varieties peaked on the second day,and that in P.×berolinensis was 50.65%higher.The peak lignin content in P.×berolinensis appeared 1 day earlier and was 27.20%higher.The peak total phenol content in P.×berolinensis appeared 1 day later and was 32.06%higher.Total flavonoid content in both varieties peaked on the first day,and that in P.×berolinensis was 48.93%higher.Correlation analysis revealed that stronger disease resistance was associated with higher activities of SOD,POD,and PAL,as well as higher contents of lignin,total phe-nols,and total flavonoids,and lower MDA content in plant stems after inoculation.Resistant varieties may improve disease resistance by rapidly activating the antioxidant enzyme system to alleviate oxidative damage,up-regulating PAL and PPO activities to promote the synthesis and oxidation of phenolic compounds,and accumulating lignin and phenolic substances to form physical and chemical defense barriers.