Origin of the resistance loci

The resistance genes that are important for breeding must, of course, already be present in some grapevine species. They are usually found where vines have always “grown up” with mildew species. This means that they are mainly found in wild species in North America. There, the presence of mildew fungi has led to the emergence of individual mutations that have resulted in resistance and have thus become established.

In order to accelerate breeding and detect the presence of such resistances in the offspring of a cross at an early stage, the resistances are assigned to so-called resistance loci. This means that statistical and genetic engineering methods are used to try to identify the section of the genome that is responsible for a particular resistance. This gene segment is then called a resistance locus. With the help of genetic engineering methods, it is thus possible to determine very early after the germination of the crossed seed whether this offspring contains certain resistances.

When breeding new resistant grapevine varieties, selection is therefore made early on for the presence of different resistance loci.

The various resistance loci originate from very different Vitis species.

The following overview shows a selection of the currently known resistance loci. It shows which Vitis species the resistances originate from, on which chromosomes they are located and how strong their effect or resistance is currently estimated to be.

What is a resistance locus?

A resistance locus (plural: resistance loci) is a specific section on a chromosome that contains genes responsible for the resistance of a plant or organism to certain diseases or pests. These genes can, for example, control the production of proteins that ward off pathogens or prevent them from spreading.

In plant breeding, the identification of such resistance loci is particularly important in order to develop more resistant varieties. One well-known example is the breeding of grape varieties that are resistant to powdery and downy mildew.

Loki name	Disease	Origin of resistance	On Chromosom	Resistance strength	Reference
Rpv1	Downy Mildew	V. rotundifolia	12	high	Merdinoglu et al., 2003
Rpv2	Downy Mildew	V. rotundifolia	18	total	Wiedemann-Merdinoglu et al., 2006
Rpv3	Downy Mildew	V. rupestris	18	partial	Bellin et al., 2009; Welter et al., 2007
Rpv4	Downy Mildew	American Vitis	4	weak	Welter et al., 2007
Rpv5	Downy Mildew	V. riparia	9	weak	Marguerit et al., 2009
Rpv6	Downy Mildew	V. riparia	12	weak	Marguerit et al., 2009
Rpv7	Downy Mildew	American Vitis	7	weak	Bellin et al., 2009
Rpv8	Downy Mildew	V. amurensis	14	high	Blasi et al., 2011
Rpv9	Downy Mildew	V. riparia	7	weak	Moreira et al., 2011
Rpv10	Downy Mildew	V. amurensis	9	high	Schwander et al., 2012
Rpv11	Downy Mildew	American Vitis	5	weak	Fischer et al., 2004
Rpv12	Downy Mildew	V. amurensis	14	high	Venuti et al., 2013
Rpv13	Downy Mildew	V. riparia	12	weak	Moreira et al., 2011
Rpv14	Downy Mildew	V. cinerea	5	-	Ochssner et al., 2016
Run1	Powdery Mildew	V. rotundifolia	12	total	Pauquet et al., 2001
Run 2.1	Powdery Mildew	V. rotundifolia	18	partial	Riaz et al., 2011
Run 2.2	Powdery Mildew	V. rotundifolia	18	partial	Riaz et al., 2011
Ren1	Powdery Mildew	V. vinifera	13	partial	Hoffmann et al., 2008
Ren2	Powdery Mildew	V. cinerea	14	partial	Dalbó et al., 2000
Ren3	Powdery Mildew	American Vitis	15	partial	Welter et al., 2007
Ren4	Powdery Mildew	V. romanetii	18	partial	Riaz et al., 2011
Ren5	Powdery Mildew	V. rotundifolia	14	total	Blanc et al., 2012
Ren6	Powdery Mildew	V. piasezkii	9	total	Pap et al., 2016
Ren7	Powdery Mildew	V. piasezkii	19	partial	Pap et al., 2016
Ren8	Powdery Mildew	American Vitis	18	partial	Zyprian et al., 2016

reference: D. Merdinoglu , C. Schneider, E. Prado, S. Wiedemann-Merdinoglu and P. Mestre 2017: Breeding for durable resistance to downy and powdery mildew in grapevine

Origin of the resistance loci

What is a resistance locus?

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