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- Title
P80 - Ribbon trichomes as a physical barrier for Plasmopara viticola infection.
- Authors
Schwandner, Anna; Malagol, Nagarjun; Schwander, Florian; Töpfer, Reinhard; Hausmann, Ludger
- Abstract
Plant hair or trichomes can be found on surfaces of different grapevine organs and are of diverse morphology, ontogeny and function. Trichome types in Vitis are described as either non-glandular, including ribbon and simple trichomes, or glandular. Ribbon trichomes are elongated and twisted and their occurrence can vary in extent from absent to sporadic up to a dense, highly hydrophobic indumentum. Ribbon trichomes can provide a first line of defense against infection with P. viticola, since the causal agent of downy mildew requires the presence of liquid water to successfully infect grapevine tissues. A dense layer of ribbon trichomes on the abaxial leaf surface holds back the sporangia and the hydrophobic environment prevents wetting after rainfall thereby impairing zoospores from hatching, approaching the stomata, and finally penetrating the leaf. In the present study, it was shown that this inhibitory effect on artificial infection in a leaf disc assay with pubescent varieties could be reduced by the use of detergents. In this way, genetic resistance can be studied independently of this physical barrier. Moreover, a F1 population of a cross between 'Lemberger' (V. vinifera) with glabrous leaves and 'Catawba' (V. labrusca x V. vinifera) with a dense indumentum was examined for the trait ribbon trichome density. QTL mapping led to the identification of a major locus on chromosome 5 of 'Lemberger' for hairlessness. Using a second biparental population, this locus was also detected in glabrous 'Morio Muskat' and is known as Leaf Hair 1 (LH1) locus from 'Muscat of Alexandria'. Additional QTL are described e.g. on chromosomes 1, 8, 10 and 15 associated with either absence or presence of ribbon trichomes, indicating the complexity of this trait. Knowledge about such underlying genetic loci can be used in breeding programs to consider ribbon trichomes as a preformed physical barrier in addition to genetic resistances in form of Rpv loci. Thus, the resilience of new cultivars to downy mildew can be reinforced, green leaf tissue preserved and the infection pressure in vineyards kept low.
- Subjects
TRICHOMES; DOWNY mildew diseases; RIBBONS; GRAPES; ZOOSPORES; LOCUS (Genetics); VITIS vinifera
- Publication
Julius-Kühn-Archiv, 2022, Issue 470, p162
- ISSN
1868-9892
- Publication type
Article