Plant Pathology (1998) 47, 723-736

A. Lebeda and D.A.C. Pink (1998)
Histological aspects of the response of wild Lactuca spp. and their hybrids, with L. sativa to lettuce downy mildew (Bremia lactucae)
Plant Pathology 47 (6), 723-736
Abstract: A histological study was carried out on the interactions between a highly virulent isolate (CS9) of Bremia lactucae (lettuce downy mildew) and wild Lactuca spp. and their interspecific hybrids with the cultivated lettuce, L. sativa. Early stages of infection (24 and 48 h after inoculation) were investigated in leaf discs from adult plants of 15 genotypes of L. sativa, L. serriola, L. virosa and L. sativa x wild Lactuca spp. The L. sativa cultivars excepted, all accessions and hybrids were completely or partially resistant at the seedling and adult plant stages, according to phenotypic expression. There were significant differences in the length of germ tubes formed 24 h after inoculation. Those on the wild Lactuca spp. were significantly shorter than those on the interspecific hybrids derived from them. There was no correlation between length of germ tube and interaction phenotype. Significant differences were recorded among the Lactuca spp. and hybrids in the development and size of infection structures and in plant tissue response. At least four types of resistance response were recognized on a microscopic level. The results provide evidence for different resistance mechanisms in various wild Lactuca spp. that cannot be distinguished by their macroscopic phenotype.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Ales Lebeda

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Bremia lactucae	Lettuce (Lactuca)