Journal of Hunan Ecological Science

【Objective】This study aims to investigate the effects of wheat powdery mildew (Blumeria graminis f. sp. tritici) infection on the growth and physiological parameters of wheat seedlings, elucida- ting the physiological defense mechanisms of wheat varieties exhibiting varying levels of resistance to this pathogen. 【Method】The experiment utilized a disease-resistant line (7D49) and a susceptible line (Xu- ezao). At the two-leaf-one-heart stage, seedlings were inoculated with B. graminis f. sp. tritici race E09. Measurements were recorded prior to inoculation (0 day) and at intervals of 2, 4, 6, 8, and 10 days post-inoculation (dpi). Key parameters included seedling shoot length, stem diameter, leaf chloro- phyll content, enzymatic activities of superoxide dismutase ( SOD ), phenylalanine ammonia-lyase (PAL), catalase (CAT), peroxidase (POD), and polyphenol oxidase (PPO), as well as malondialde- hyde (MDA) content. 【Result】After inoculation, the shoot length of 7D49 was significantly greater than that of Xuezao, accompanied by a thicker stem diameter. Although chlorophyll content decreased signifi- cantly in both lines over time, 7D49 consistently exhibited higher chlorophyll levels compared to Xuezao at each measured time point (P<0. 05). Notably, the MDA content in 7D49 remained stable compared to pre-inoculation levels, while Xuezao displayed a significant decline (P<0. 05). Analysis of defense enzyme activities indicated that SOD activity in 7D49 significantly increased, peaking at 4 dpi before gradually declining, whereas Xuezao experienced a marked reduction in SOD activity (P<0. 05). Addi- tionally, significant decreases were observed in both CAT and PAL activities across both lines ( P < 0. 05). PPO activity initially decreased before rising in both varieties, while POD activity displayed no discernible trend. 【Conclusion】The resistant line 7D49 demonstrated a reduced impact from powdery mildew infection on growth parameters. After inoculation, 7D49 maintained significantly a notable in- crease in SOD activity, contributing to its resistance against B. graminis f. sp. tritici. These findings provide critical insights into the interactions between wheat and the powdery mildew pathogen.

wheat; disease resistance; powdery mildew; defense enzyme activity