Li Y H, Windham M T, Trigiano R N, Fare D C, Spiers J M, Copes W E
Department of Entomology and Plant Pathology, University of Tennessee, Knoxville 37996-4560.
United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Floral & Nursery Plants Research Unit, McMinnville, TN 37110.
Plant Dis. 2007 Jun;91(6):664-668. doi: 10.1094/PDIS-91-6-0664.
Infection and colonization of eight daylily cultivars, which varied in resistance to daylily rust, by Puccinia hemerocallidis was studied macroscopically and microscopically. After germination of urediniospores, appressoria formed at the tip of germ tubes and the fungus penetrated the host through stomatal openings 2 days after inoculation (DAI). Under the infection sites, intercellular hyphae aggregated and formed uredia, which released urediniospores 8 DAI. Resistant cultivars, characterized by the development of rapid death of host cells, were separated into three qualitative categories based on absence and presence of necrotic lesions without or with sporulation. In highly resistant cvs. Prairie Blue Eyes and Bertie Ferris, no macroscopic disease symptoms were observed on leaf surfaces although a few collapsed cells were detected microscopically. Both resistant and moderately resistant reactions were characterized by necrotic lesions with many collapsed cells under infection sites. The difference between these two reactions was that uredia and urediniospores were observed in the moderately resistant cv. Chicago Apache, but not in resistant cvs. Buttered Popcorn and Stella De Oro. Susceptible cultivars, characterized by the absence of a hypersensitive response, were separated into two qualitative categories based on restriction of intercellular hyphal growth that delayed development of uredia and formation of urediniospores. Compared to the susceptible cv. Pardon Me, moderately susceptible cvs. Mary Todd and Chorus Line had a delayed latent period and reduced amount of sporulation. The results indicate that hypersensitive cell death is one of the resistance responses to daylily rust. Necrotic lesions on leaf surfaces are associated with the number of collapsed host cells. Delayed latent period and reduced sporulation that resulted from restriction of intercellular hyphal growth could represent another type of resistance response in the daylily-rust pathosystem.
对八个黄花菜品种（它们对黄花菜锈病的抗性各不相同）被萱草柄锈菌感染和定殖的情况进行了宏观和微观研究。夏孢子萌发后，附着胞在芽管顶端形成，接种2天后（DAI）真菌通过气孔侵入寄主。在感染部位下方，细胞间菌丝聚集形成夏孢子堆，8 DAI时释放出夏孢子。抗性品种的特征是寄主细胞迅速死亡，根据有无坏死病斑（无或有孢子形成）分为三个定性类别。在高抗品种“草原蓝眼”和“伯蒂·费里斯”中，叶片表面未观察到宏观病害症状，尽管在显微镜下检测到一些塌陷细胞。抗性和中抗反应的特征都是在感染部位有许多塌陷细胞的坏死病斑。这两种反应的区别在于，在中抗品种“芝加哥阿帕奇”中观察到了夏孢子堆和夏孢子，而在抗性品种“奶油爆米花”和“斯黛拉·德奥罗”中未观察到。感病品种的特征是没有过敏反应，根据细胞间菌丝生长受限（这延迟了夏孢子堆的发育和夏孢子的形成）分为两个定性类别。与感病品种“请原谅我”相比，中感品种“玛丽·托德”和“歌舞线上”的潜伏期延迟，孢子形成量减少。结果表明，过敏细胞死亡是对黄花菜锈病的抗性反应之一。叶片表面的坏死病斑与塌陷寄主细胞的数量有关。细胞间菌丝生长受限导致的潜伏期延迟和孢子形成减少可能代表了黄花菜-锈病病理系统中的另一种抗性反应。
