Aspetti fisiopatologici dell’interazione carciofo – Sclerotinia sclerotiorum
Author(s)
Marcucci, Emanuela
Date Issued
February 27, 2009
Type
Doctoral Thesis
Abstract
The globe artichoke is susceptible to various pathogenic fungi coming both from soil and from air
transmission. The most widespread and damaging diseases are caused by soil born pathogens,
including the dangerous necrotrophic fungus Sclerotinia sclerotiorum. This pathogen causes soft
crown rot and detechment of taproots by action of pectolytic and cellulosolytic enzymes. The most
frequent necessity of seeking alternative defence to traditional chemical systems motivated great
interest in defence systems based on “systemic acquired resistance” (SAR). In the present study
three chemical resistance inducers have been taken into consideration: BTH (acibenzolar-S-methyl)
50 μM , FOSFATO (KH2PO4) 25 μM and BABA ( -AminoButyric Acid) 100 μM. Two globe
artichoke cultivars were considered: C3 and Exploter. The first is widespread in Latium region, the
other is a new cultivar very promising about his qualitative and productive features.
Globe artichoke plants (belonging to C3 and Exploter cultivars) have been grown in controlled
climatic conditions (temperature 22°C, relative humidity 70%, photoperiod of 12 hours light and 12
hours dark). Two treatments with three chemical inducers were performed with two weeks interval.
After each treatment leaf samples were taken from the artichoke plant to evaluate the presence of
phatogenesis-related proteins (PR): peroxidase, chitinase and -1,3-glucanase, considered
biochemical marker of resistance. After treatments S. sclerotiorum was inoculated in globe
artichoke plant. Seven days after inoculation samples of both infected and healthy globe artichoke
plants were collected to evaluate the PR production. The proteins were extracted from leaf samples
and from plant crowns by freezing with liquid nitrogen and pulverising the tissues in a cold mortar.
Then cold buffer (Tris-HCl pH 7,8 + polyvinylpolypyrrolidone) was added in the ratio 1:2 w/v, the
extracts were centrifuged and subiected to dialysis against distilled water at 4°C. Finally peroxidase,
chitinase and -1,3-glucanase were both quantitatively and qualitatively analyzed.
The disease index calculated in treated and inoculated plants showed un increase in both cultivars in
comparison whit control, particularly in Exploter cultivar after the treatment with BABA.
The quantitative and qualitative analysis of three PR proteins showed high presence of BABA, and
FOSFATO, the two best of the three chemical resistance inducers.
The experiments show that three activators used as resistance inducers in two globe artichoke
cultivars can help the plant to defend itself against pathogen’s attack. In fact, the disease indexes in
treated plants result lower comparated with control plants. The chemical resistance inducers
anticipate the signals of pathogen to regulate the overexpression of genes involved in the resistance
without considerable differences among two artichoke cultivars. These results are in agreement with
experiments performed in other horticultural crops (melon, cucumber and zucchini). Finally from
this work emerges the good perspective to use resistance inducers, particularly BABA, in
alternative to traditional chemical systems.
Additional information
Dottorato di ricerca in Protezione delle piante
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