Identification of molecular markers linked to Pm13, an Aegilops longissima gene conferring resistance to powdery mildew in wheat

Incorporation of competitive quality and resistance against the most important fungal diseases (powdery and downy mildew) in a cultivar is one of the most important aims of grapevine breeding. In the 20th century, the most advanced results in grapevine resistance breeding were achieved by French researchers. They used resistant cultivars in more than 30% of their growing areas. In these varieties, North American wild Vitisspecies were the resistance gene sources. The discovery of immunity-like resistance of Muscadinia rotundifolia opened new perspectives in resistance breeding. M. rotundifolia harbours a dominant powdery mildew gene, providing resistance in highquality cultivars after back-crosses with V. vinifera varieties. M. rotundifolia has been involved in the Hungarian grape breeding programs since 1996, thanks to a French-Hungarian variety exchange. In addition to traditional selection methods, application of MAS (Marker Assisted Selection) based on various types ofmolecular markers, can provide additional tools for these efforts. Run1 locus, responsible for powdery mildew resistance, was identified in Muscadinia rotundifolia. Molecular markers closely linked to this locus are very significant in screening progenies deriving from M. rotundifolia and V. vinifera crosses, making possible the discrimination between resistant and susceptible genotypes at DNA level. In our analyses BC5 progeny of {(M. rotundifola×V. vinifera) BC4}×Cardinal (V. vinifera) tested for powdery symptoms were analysed with PCR-RFLP (GLP1- 12P1P3) and microsatellite markers (VMC4f3.1, VMC8g9). Our results proved the applicability of the linked markers and reliability of marker assisted selection.

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Evaluation and Pre-selection of New Grapevine Genotypes Resistant to Downy and Powdery Mildew, Obtained by Cross-Breeding Programs in Spain

Frontiers in Plant Science ◽

10.3389/fpls.2021.674510 ◽

2021 ◽

Vol 12 ◽

Author(s):

Leonor Ruiz-García ◽

Pilar Gago ◽

Celia Martínez-Mora ◽

José Luis Santiago ◽

Diego J. Fernádez-López ◽

...

Keyword(s):

Molecular Markers ◽

Powdery Mildew ◽

Simple Sequence Repeat ◽

Selection Process ◽

Sequence Repeat ◽

Sources Of Resistance ◽

Breeding Programs ◽

Phenotypic Resistance ◽

Simple Sequence ◽

Selection Of

The need to develop an environmentally friendly, sustainable viticulture model has led to numerous grapevine improvement programmes aiming to increase resistance to downy and powdery mildew. The success of such programmes relies on the availability of protocols that can quantify the resistance/susceptibility of new genotypes, and on the existence of molecular markers of resistance loci that can aid in the selection process. The present work assesses the degree of phenotypic resistance/susceptibility to downy and powdery mildew of 28 new genotypes obtained from crosses between “Monastrell” and “Regent.” Three genotypes showed strong combined resistance, making them good candidates for future crosses with other sources of resistance to these diseases (pyramiding). In general, laboratory and glasshouse assessments of resistance at the phenotype level agreed with the resistance expected from the presence of resistance-associated alleles of simple sequence repeat (SSR) markers for the loci Rpv3 and Ren3 (inherited from “Regent”), confirming their usefulness as indicators of likely resistance to downy and powdery mildew, respectively, particularly so for downy mildew.

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Pyramiding resistance genes and widening the genetic base of the apple (Malus × domestica Borkh.) crop

Italus Hortus ◽

10.26353/j.itahort/2021.1.3243 ◽

2021 ◽

Vol 28 (1) ◽

pp. 32

Author(s):

Raffaele Testolin ◽

Luigi Falginella ◽

Alberto De Carli ◽

Gloria De Mori ◽

Guido Cipriani

Keyword(s):

Molecular Markers ◽

Disease Resistance ◽

Powdery Mildew ◽

Resistance Genes ◽

Field Observations ◽

Vf Gene ◽

Malus Domestica Borkh ◽

Genetic Base ◽

Apple Cultivars ◽

New Cultivars

Apple breeding is active worldwide and yet the apple crop is in a precarious state as it relies on few dominant cultivars and only the Rvi6 (formerly Vf) gene, that confers resistance to scab, has been extensively exploited in the cultivars entered the market in recent years. However, there are some 20 disease resistance genes described in apple and the apple germplasm includes thousands of accessions in the repositories. In this paper, a breeding programme is described, whereby 36 genotypes, including ancient and contemporary apple cultivars, were crossed to produce a new set of selections that combine extensive genetic resources with pyramided resistance genes to several apple diseases, such as scab and powdery mildew. The 110 cross combinations carried out successfully, of the 260 initially planned, produced 7,876 offsprings, reduced to 2,969 after screening with molecular markers associated with five resistance genes. Selections with three or two resistance genes and good agronomic characteristics were kept for further field observations with the aims of creating new cultivars for the market and new parents for future breeding projects

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Mapping of crown rust (Puccinia coronata f. sp. avenae) resistance gene Pc54 and a novel quantitative trait locus effective against powdery mildew (Blumeria graminis f. sp. avenae) in the oat (Avena sativa) line Pc54

Phytopathology ◽

10.1094/phyto-10-21-0445-r ◽

2022 ◽

Author(s):

Belayneh Admassu Yimer ◽

Kathy Esvelt Klos ◽

Irene Griffiths ◽

Alexander Cowan ◽

Catherine Howarth

Keyword(s):

Molecular Markers ◽

Powdery Mildew ◽

Resistance Gene ◽

Interval Mapping ◽

Crown Rust ◽

The Novel ◽

Unknown Gene ◽

Trait Locus ◽

Separate Identity ◽

Genomic Locations

The Pc54 oat line carries the crown rust resistance gene ‘Pc54’ and an unknown gene effective against powdery mildew. In this study two recombinant inbred line populations were developed to identify the genomic locations of the two genes and producing lists of molecular markers with a potential for marker assisted selection. The RILs and parents were phenotyped for crown rust and powdery mildew in a controlled environment. They were also genotyped using the 6K Illumina Infinium iSelect oat SNP chip. Multiple interval mapping placed Pc54 on the linkage group Mrg02 (chromosome 7D) and the novel powdery mildew QTL ‘QPm.18’ on Mrg18 (chromosome 1A) both in the mapping and validating population. A total of nine and 31 significant molecular markers were identified linked with the Pc54 gene and QPm.18, respectively. Reactions to crown rust inoculations have justified separate identity of Pc54 from other genes and QTL that have previously been reported on Mrg02 except for ’qPCRFd’. Pm3 is the only powdery mildew resistance gene previously mapped on Mrg18. However, the pm3 differential line, Mostyn was susceptible to the powdery mildew race used in this study suggesting that Pm3 and QPm.18 are different genes. Determining the chromosomal locations of Pc54 and QPm.18 is helpful for better understanding the molecular mechanism of resistance to crown rust and powdery mildew in oats. Furthermore, SNPs and SSRs that are closely linked with the genes could be valuable for developing PCR based molecular markers and facilitating the utilization of these genes in oat breeding programs.

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