Linkage of downy mildew resistance genes Pd
1 and Pd
2from Allium roylei Stearn in progeny of its interspecific hybrid with onion (A. cepa L.)

Vries, J. N. de; Wietsma, W. A.; Jongerius, M. C.

doi:10.1007/bf00023546

Cited by 19 publications

(8 citation statements)

References 14 publications

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“…Vegetable germplasm developed at Cornell are generally released or licensed nonexclusively to maximize use of these materials by public and private researchers. Resistance to downy mildew caused by Peronospora destructor was identified in A. roylei as two weakly linked genes, Pd1 and Pd2, and has been transferred into cultivated onion (De Vries et al, 1992a;Kofoet et al, 1990;Scholten et al, 2007). This transfer is seen as a large step in reducing fungicide use and subsequent environmental impacts (Scholten et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of Onion (Allium cepa L.) Lines and Hybrids Possessing Bs1 for Resistance against Multiple Isolates of Botrytis squamosa

et al. 2015

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Onion (Allium cepa L.) lines resistant to Botrytis leaf blight (BLB) were produced by backcrossing the Bs1 BLB resistance of Allium roylei Stearn into cultivated onion. This study evaluated important issues for the commercial use of BLB‐resistant onions: the relative degree of BLB control possible when Bs1 is homozygous rather than heterozygous, the control achieved against multiple pathogen isolates, and the potential for negative traits associated with transfer of Bs1. Homozygous BLB‐resistant onions tested in inoculated growth chamber screens with five distinct Botrytis squamosa Walker isolates and in naturally infested regional field trials showed significantly lower BLB symptoms than susceptible commercial hybrid controls. F1 hybrids heterozygous for the Bs1 gene showed levels of BLB symptoms between those of the homozygous resistant and susceptible controls, confirming previous reports of partial dominance. The difference in BLB control in plants heterozygous for Bs1 compared with homozygous plants was more noticeable under heavier disease pressure. Hybrids heterozygous for Bs1 had similar level of BLB control in most of the field trials as their parental homozygous BLB‐resistant lines, indicating that either heterozygous or homozygous BLB resistant hybrids could be used commercially for BLB control. There were no differences in the degree of pathogenicity across the five B. squamosa isolates, which were genetically different based on polymorphism for DNA markers, or among the naturally occurring pathogens present at the six different field locations used. No obvious association was noted between presence of the Bs1 resistance gene with unfavorable characteristics such as reduced bulb size or yield.

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Section: Discussionmentioning

confidence: 99%

Evaluation of Onion (Allium cepa L.) Lines and Hybrids Possessing Bs1 for Resistance against Multiple Isolates of Botrytis squamosa

et al. 2015

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“…As the interspecific hybrid was completely resistant to downy mildew and its backcross progeny with onion segregated in a 1:1 ratio, concluded that resistance to downy mildew in A. roylei could be explained by the presence of a single dominant locus which was named Pd1. Later progenies, obtained by selfing these interspecific hybrid plants, were analyzed, and it became less clear that the inheritance of resistance to downy mildew was based on one dominant gene only, as the observed segregation ratios significantly deviated from the expected 3:1 ratio (De Vries et al 1992a).…”

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confidence: 99%

The long and winding road leading to the successful introgression of downy mildew resistance into onion

et al. 2007

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Downy mildew resistance originating from Allium roylei Stearn provides a complete resistance to onions and is based on one, dominant gene. Since A. roylei can successfully be hybridized with onion (A. cepa L.), a breeding scheme aimed at the introgression of this gene was initiated ca. 20 years ago. Several setbacks in this programme were encountered, firstly the identified molecular marker linked to the downy mildew resistance locus became increasingly difficult to use and finally lost its discriminating power and secondly the final step, making homozygous introgression lines (ILs), turned out to be more difficult then was hoped. GISH analysis showed that the chromosomal region harbouring the resistance locus was the only remaining piece of A. roylei in the nuclear background of onion and it also confirmed that this region was located on the distal end of chromosome 3. It was hypothesized that some factor present in the remaining A. roylei region was lethal when homozygously present in an onion genetic background. The identification of an individual with a smaller and more distally located introgression fragment and homozygous ILs in its progeny validated this hypothesis. With the help of these nearly isogenic lines four AFLP Ò markers closely linked to the resistance gene were identified, which can be used for marker-aided selection. The introduction of downy mildew resistance caused by Peronospora destructor into onion is a significant step forward in the development of environmentally-friendly onion cultivars.

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“…In a diploid hybrid between A. roylei (♀) and A. cepa , PMCs with eight bivalents represented the largest category and those with univalents were very limited in number (De Vries et al. 1992b).…”

Section: Discussionmentioning

confidence: 99%

“…This method considerably shortened the time to obtain the alloplasmic male sterile lines of A. cepa harbouring the cytoplasm from A. roylei. In a diploid hybrid between A. roylei ($) and A. cepa, PMCs with eight bivalents represented the largest category and those with univalents were very limited in number (De Vries et al 1992b). This result indicates that an allosynapsis and a subsequent recombination are able to occur frequently between the homoeologous chromosomes in the diploid hybrid.…”

Section: Discussionmentioning

confidence: 99%

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Production of novel alloplasmic male sterile lines in Allium cepa harbouring the cytoplasm from Allium roylei

Iwata

Yamauchi

et al. 2011

Plant Breeding

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With 3 figures and 5 tables Abstract To develop alloplasmic lines of Allium cepa, cytoplasmic substitution by continuous backcrossing was performed using Allium roylei as a cytoplasm donor. The chromosomes of a single F1 plant between A. roylei (♀) and shallot were doubled, and then backcrossing with shallot was performed to produce BC1 as allotriploids. One allotriploid plant was used for backcrossing with bulb onion to produce BC2 with 2n = 16, 17, 23 and 24. The BC2 plants possessing 16 chromosomes were checked for pollen fertility in Yamaguchi, Japan (N34°11′), and then backcrossed with bulb onion again to evaluate their seed‐setting characteristics. The pollen fertility of BC2 ranged from 0% to more than 10%. A large number of plants showed no pollen fertility (0%). In Kagawa and Hokkaido, most of the plants were completely pollen sterile, while the percentages of seed sets in BC2 were high enough to reproduce BC3 seeds. The results of this study revealed that an exploitation of A. roylei cytoplasm would be useful for the development of a novel cytoplasmic male sterility line in Allium.

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Linkage of downy mildew resistance genes Pd 1 and Pd 2from Allium roylei Stearn in progeny of its interspecific hybrid with onion (A. cepa L.)

Cited by 19 publications

References 14 publications

Evaluation of Onion (Allium cepa L.) Lines and Hybrids Possessing Bs1 for Resistance against Multiple Isolates of Botrytis squamosa

Evaluation of Onion (Allium cepa L.) Lines and Hybrids Possessing Bs1 for Resistance against Multiple Isolates of Botrytis squamosa

The long and winding road leading to the successful introgression of downy mildew resistance into onion

Production of novel alloplasmic male sterile lines in Allium cepa harbouring the cytoplasm from Allium roylei

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