Abstract:

The histopathological manifestation of interactions of poplars cultivars and leaf rust(Melampsora larici-populina Kleb.)with different compatibilities was investigated by using whole-leaf cleaning and staining technique at various times after inoculation. The results showed that the urediospore germinated 6 h after inoculation on poplar leaf, and then germ tube grew into stoma and haustorium was formed in the host cell 24 h after inoculation. Germ-tube always branched into several tubes and infected two stomas, or several tubes infected one stoma at the same time. Resistance expression occurs 24 h after inoculation, but there were differences among different compatible combinations. As to resistant host combination, urediospore germinating process and growth rate of germ tube were restrained, and haustorium formed later (36 h after inoculation) and small in number; the number of substomatal vesicle on leaf was small and cell death frequently occured. As to compatible combination, haustorium formed 24 h after inoculation. The number of haustorium and the size of colony in resistant species were smaller than those of the susceptible ones, but larger than the near-immune ones.

Key words: Poplar, Melampsora larici-populina, Histology