Induction of different pathogenesis-related cDNAs in grapevine infected with powdery mildew and treated with ethephon

• Published in: Plant pathology Vol. 48; no. 3; pp. 325 - 336
• Main Authors: Jacobs, A.K, Dry, I.B, Robinson, S.P
• Format: Journal Article
• Language: English
• Published: Oxford, U.K. and Cambridge, USA Blackwell Science Ltd 01.06.1999; Blackwell; Wiley Subscription Services, Inc
• Subjects: Agronomy. Soil science and plant productions; amino acid sequences; beta-glucanase; Biological and medical sciences; biological resistance; chitinase; complementary DNA; cultivars; enzyme activity; ethephon; fruits; Fundamental and applied biological sciences. Psychology; fungal diseases of plants; genbank/af053341; genbank/af053750; gene expression; Genetics and breeding of economic plants; grape; infection; leaves; molecular sequence data; pathogenesis-related proteins; Pest resistance; Plant pathogens; powdery mildew; resistance; Uncinula necator; Varietal selection. Specialized plant breeding, plant breeding aims; Vitis vinifera; Chitinase; Plant pathogen; Vitis vinifera; Fungi; Disease resistance; Vitidaceae; Dicotyledones; Angiospermae; Uncinula necator; Ascomycetes; Protection; Thallophyta; Glucanase; Enzyme; Induction; Gene expression; Pathogenesis related protein; Stress; Infection; Sensitivity resistance; Complementary DNA; Fruit crop; Glycosidases; Hydrolases; Defense mechanism; Spermatophyta; O-Glycosidases
• ISSN: 0032-0862; 1365-3059
• DOI: 10.1046/j.1365-3059.1999.00343.x

Uncinula necator, the causal agent of grapevine powdery mildew, was found to elevate the activity of the pathogenesis‐related (PR) proteins, chitinase and β‐1,3‐glucanase in leaves and berries of a number of susceptible grapevine (Vitis vinifera) cultivars. The increase in hydrolytic activity was directly related to the severity of powdery mildew infection on both leaves and berries but no systemic induction was observed in uninfected tissues. A number of cDNA clones encoding various PR proteins, including chitinases (PR‐2), β‐1,3‐glucanases (PR‐3) and thaumatin‐like (TL) proteins (PR‐5), were isolated and their expression in response to powdery mildew infection examined. PR genes encoding extracellular proteins were most strongly induced in infected leaves, including an acidic class III chitinase (VvChi3), a basic class I glucanase (VvGlub) and a thaumatin‐like protein (VvTl2). A basic class I chitinase (VvChi1b) was also detected, but only in severely infected leaves. A similar pattern of PR gene induction was observed in mildew‐infected preveraison berries, with the exception of VvChi1b, which was not detected. Chitinase and β‐1,3‐glucanase enzyme activities were also found to be highly induced in leaves and preveraison berries by ethephon treatment. The pattern of chitinase gene induction by ethephon, however, was markedly different for mildew infection, with no apparent induction of VvChi3 but a marked increase in the transcript level of an acidic class IV chitinase, VvChi4. These results demonstrate that the leaves and preveraison berries of grapevine respond to environmental and stress‐related stimuli by the expression of specific PR genes but that the induction of these genes during pathogen invasion does not afford complete protection of these tissues against Uncinula necator. The following abbreviations have been used: Tris: 2‐amino‐2‐(hydroxymethyl)‐1,3‐propanediol; EDTA: ethylenediaminetetra‐acetic acid; PVPP: polyvinylpolypyrrolidone. The GenBank accession numbers for VvChi1b and VvGlub are AF053341 and AF053750, respectively.