Articles
RESISTANCE FACTORS OF A WILD SPECIES OF SUNFLOWER, HELIANTHUS RESINOSUS, TO SCLEROTINIA SCLEROTIORUM.
Article number
381_88
Pages
642 – 645
Language
Abstract
We have pointed out the structural originality of Helianthus resinosus, wild species resistant to white rot caused by Sclerotinia sclerotiorum, as compared with H. annuus, using histochemical study by observation in visible-light and epifluorescence and biochemical analysis. H. resinosus possesses pre-existent defence mechanisms (cortical sclerified fiber cells, sclerenchyma, numerous and voluminous glandular hairs, epidermic flavonoids), not present in H. annuus. After infection (very limited in H. resinosus) there is a transformation of a bract compound as well as oxidization of epidermic flavonoids.
In the leaves, there is a modification of glandular hair content and a very strong accumulation of caffeic derivatives in stomates (not present in healthy leaf stomates), as well as formation of a delimited area (phellem type) between the healthy and necrotic part.
In this healthy part, there is a strong accumulation of caffeic derivatives which are definitely involved in resistance, and we have stressed the important prevalence of certain majority caffeoylquinic compounds (CQ) in H. resinosus. The level of CQ in tolerant genotypes of cultivated sunflowers is also always higher than that found in susceptible genotypes.
Pre-existent histological structures, as well as a very high level of CQ are involved in the multiple mechanisms found during resistance to S. sclerotiorum in H. resinosus.
In the leaves, there is a modification of glandular hair content and a very strong accumulation of caffeic derivatives in stomates (not present in healthy leaf stomates), as well as formation of a delimited area (phellem type) between the healthy and necrotic part.
In this healthy part, there is a strong accumulation of caffeic derivatives which are definitely involved in resistance, and we have stressed the important prevalence of certain majority caffeoylquinic compounds (CQ) in H. resinosus. The level of CQ in tolerant genotypes of cultivated sunflowers is also always higher than that found in susceptible genotypes.
Pre-existent histological structures, as well as a very high level of CQ are involved in the multiple mechanisms found during resistance to S. sclerotiorum in H. resinosus.
Authors
L. Mondolot-Cosson, C. Andary
Keywords
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