Glucosinolate content in susceptible and resistant Chinese cabbage varieties during development of clubroot disease.

摘要

The glucosinolate content in Chinese cabbage during the development of clubroot disease caused by the obligate biotroph Plasmodiophora brassicae was investigated using 2 susceptible and 2 resistant varieties, and 3 classes of glucosinolates, aliphatic (= alkenyl), aromatic and indolic were analysed. Between the susceptible varieties Granat and Osiris and the resistant varieties Parkin and Yuki, there were significant differences in glucosinolate pattern. The total glucosinolate content in roots ofthe 2 susceptible varieties was higher throughout the experimental period than in roots of the 2 resistant varieties. Osiris showed the highest glucosinolate content of all the varieties investigated (c. 3-fold higher than Granat and c. 5-fold higher than Parkin and Yuki). After infection with P. brassicae, the indole glucosinolates increased after 14 and 20 d in roots of Granat and Osiris, respectively, whereas there was no difference between infected and control roots in Parkin and Yuki. The aliphaticglucosinolates were also enhanced in infected roots of Granat, whereas Osiris showed a very high content of aliphatic glucosinolates during the whole experimental period. Roots of Parkin and Yuki grown in the presence of Plasmodiophora spores showed anelevated concn of aromatic glucosinolates after 14 and 30 d, respectively, which was not found in Granat and Osiris. Total seed glucosinolate content appeared to be correlated with the susceptibility of the Chinese cabbage varieties tested. Eight different susceptible varieties showed higher total glucosinolate contents than the 2 resistant varieties. Treatment of plants of the varieties Parkin and Granat with salicylic acid and jasmonic acid resulted in increased amounts of glucosinolates, although differences in the response were observed between the 2 treatments. Jasmonic acid induced mainly indole glucosinolates in the leaves, whereas salicylic acid induced indole glucosinolates also in the roots of both varieties. In the variety Parkin, inductionof aliphatic and aromatic glucosinolates was also observed after jasmonate treatment. Although the variety Parkin showed no clubroot symptoms, fungal structures were detected within the roots using SEM. It is suggested that this variety be described as tolerant rather than resistant. The potential role of different glucosinolates in plant-pathogen interactions is discussed.