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  • Publication
    Accès libre
    Site-specific field resistance of grapevine to Plasmopara viticola correlates to altered gene expression and was not modulated by the application of organic amendments
    (2011)
    Thuerig, Barbara
    ;
    Slaughter, Ana R.
    ;
    Marouf, Elaheh
    ;
    ; ;
    Tamm, Lucius
    The influence of site on resistance of grapevine (cv. Chasselas) to Plasmopara viticola was evaluated. Grapevine leaves from three vineyards in the region of Lake Neuchâtel (Switzerland) were tested for their susceptibility to P. viticola in the lab in five successive years (2004–2008), and the expression levels of four selected defence-related genes (Glucanase, Lipoxygenase 9, 9-cis epoxycarotenoid dioxygenase, Stilbene synthase) were studied in 1 year. In all 5 years of examination, differences between sites were substantial. In four out of 5 years, plants from site Hauvernier were much less susceptible to P. viticola than plants from site Auvernier. In another year, differences were less pronounced but still significant for one leaf age. Susceptibility of plants from a third site (Concise) varied from year to year. Differences in the genetic background were excluded by microsatellite analysis. Differences in susceptibility were mirrored in the constitutive expression pattern of four defence-related genes, with samples from the Hauterive site clearly separated from samples of the other two sites in redundancy analysis. Furthermore, it was evaluated whether site-specific resistance can be modulated by agronomic practices such as the application of organic amendments. In two commercial vineyards (cv. Pinot noir), soils had either not (control) or yearly (compost) been amended with a compost for the last 9 years. Leaves from plants grown in any of the two treatments did not differ in their susceptibility to P. viticola in both years of examination. Additionally, under controlled conditions, none of 19 different composts amended to the substrate of grapevine seedlings or cuttings affected their susceptibility to P. viticola, but 8 out of 19 composts reduced severity in the control bioassay Arabidopsis thaliana—Hyaloperonospora arabidopsidis, indicating that a modulation of site-specific susceptibility of grapevine plants by organic amendments is at the very least, difficult.
  • Publication
    Accès libre
    Identification of genes expressed during the compatible interaction of grapevine with Plasmopara viticola through suppression subtractive hybridization (SSH)
    (2011)
    Legay, Guillaume
    ;
    Marouf, Elaheh
    ;
    Berger, Dave
    ;
    ; ;
    Slaughter, Ana R.
    Grapevine (Vitis vinifera) is the most widely cultivated and economically important fruit crop, but is susceptible to a large number of diseases. Downy mildew, caused by the obligate biotrophic oomycete pathogen Plasmopara viticola, is a common disease present in all regions where vines are cultivated. We used suppression subtractive hybridization (SSH) to generate two cDNA libraries enriched for transcripts induced and repressed, respectively, in the susceptible grapevine cultivar Chasselas 24 h after inoculation with P. viticola. Differential screening on glass slide microarrays yielded over 800 putative genes that were up-regulated in response to P. viticola infection and over 200 that were down-regulated. One hundred and ninety four of these, were sequenced, identified and functionally categorised. Transcript abundance of twelve genes over a 48 h time course was examined by reverse transcriptase quantitative real-time PCR (RT-qPCR). Ten of these genes were induced/enhanced by P. viticola challenge, confirming the results of the SSH. The vast majority of the genes identified are related to defence. Interestingly, many genes involved in photosynthesis were down-regulated.
  • Publication
    Accès libre
    Beta-aminobutyric acid-induced resistance in grapevine against downy mildew: involvement of pterostilbene
    (Springer, 2008)
    Slaughter, Ana R.
    ;
    Hamiduzzaman, Mollah Md.
    ;
    Katia Gindro
    ;
    ;
    BABA, a non-protein amino acid, was used to induce resistance in grapevine against downy mildew. BABA-induced resistance was observed in the susceptible cv. Chasselas as well as in the resistant cv. Solaris. Following BABA treatment, sporulation of Plasmopara viticola was strongly reduced and the accumulation of stilbenes increased with time following infection. Induction of trans-piceide, trans-resveratrol and, more importantly, of trans-ɛ- and trans-δ-viniferin and trans-pterostilbene was observed in BABA-primed Chasselas. On the other hand, induction of trans-resveratrol, trans δ-viniferin and trans-pterostilbene was observed in BABA-primed Solaris. The accumulation of stilbenes in BABA-primed Solaris was much higher than that found in BABA-primed Chasselas. Furthermore, BABA-treatment of Solaris led to a rapid increase in transcript levels of three genes involved in the phenylpropanoid pathway: phenylalanine ammonia lyase, cinnamate-4-hydroxylase and stilbene synthase. BABA-primed Chasselas showed increased transcript levels for cinnamate-4-hydroxylase and stilbene synthase. Here we show that pre-treatment of a susceptible grapevine cultivar with BABA prior to infection with P. viticola primed the accumulation of specific phytoalexins that are undetectable in non-BABA-primed plants. As a result, the susceptible cultivar became more resistant to downy mildew.