Progress 08/01/03 to 07/30/07
Outputs
This final report documents research conducted under a grant from the USDA National Research Initiative (NRI) on major potyvirus resistances in the cucurbits (cucumber, melon, and watermelon). The potyviruses are a major group of viruses that routinely incite serious losses in the cucurbits. If virus resistances in the cucurbits were syntenic, then markers developed for one cucurbit will be useful to select resistance in other cucurbits, saving time and resources. We identified a marker tightly linked with the recessive zym locus of cucumber, which conditions resistance to Zucchini Yellow Mosaic Virus and cosegregates with other potyvirus resistances. Comparative mapping of this marker in melon and watermelon revealed no linkage with ZYMV resistances in these two cucurbits. This result indicates that ZYMV resistances in cucumber, melon, and watermelon are not syntenic. Eukaryotic initiation factors (EIF) 4E and iso4E have been associatated with recessive potyvirus
resitances in a number of plants. We synthesized a fosmid library of cucumber and cloned and sequenced genomic regions from cucumber carrying EIF4E and EIF(iso)4E. These cucumber sequences were compared to the EIF4E and EIF(iso)4E genomic regions in melon. The cucumber and melon regions were highly syntenic, carrying the same genes in the same orientations except for the insertion of a retroviral element in the EIF4E region of cucumber. These two genes were mapped in cucumber and watermelon as candidate genes for the recessively inherited ZYMV resistances. Both genes segregated independently from zym in cucumber; however EIF4E showed linkage to the recessive zym locus of watermelon. Although ZYMV resistances in cucumber, melon, and watermelon are not syntenic, our results revealed strong synteny between the cucumber and melon genomes and EIF4E as a candidate gene for the zym locus of watermelon.
Impacts
This research will provide information on the virus resistance in cucumber, melon, and watermelon and reveal if the same genes control resistance to Zucchini Yellow Mosaic Virus are the same in these cucurbits.
Publications
- No publications reported this period
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Progress 01/01/06 to 12/31/06
Outputs
This report documents research conducted under a grant from the USDA National Research Initiative (NRI) on major potyvirus resistances in the cucurbits (cucumber, melon, and watermelon). The potyviruses are a major group of viruses that routinely incite serious losses in the cucurbits. If virus resistances in the cucurbits are syntenic, then markers developed for one cucurbit will be useful to select resistance in other cucurbits, saving time and resources. We are mapping candidate genes for eiF4E and eiF(iso)4E as candidate genes for the recessively inherited ZYMV resistances in cucumber and watermelon. We already demonstrated that ZYMV resistances in cucumber and melon are non-syntenic. We synthesized a cucumber fosmid library as a resource for genomic sequencing to reveal useful polymorphisms.
Impacts
This research will provide information on the virus resistance in cucumber, melon, and watermelon and reveal if the same genes control resistance to Zucchini Yellow Mosaic Virus are the same in these cucurbits.
Publications
- Eid, S., Y. Abou-Jawdah, S. El-Mohtar, H. Sobh, and M.J. Havey. 2006. Tolerance in cucumber to cucurbit yellow stunting disorder virus. Plant Dis. 90:645-649.
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Progress 01/01/05 to 12/31/05
Outputs
This report documents research conducted under a grant from the USDA National Research Initiative (NRI) on major potyvirus resistances in the cucurbits (cucumber and melon). The potyviruses are a major group of viruses that routinely incite serious losses in cucumber and melon. Many viruses infect cucumber and numerous sources of resistance are known. Breeding cucumber for resistance to these viruses is a time consuming and expensive process because of independently inherited resistance loci, the similar phenotypes caused by different viruses, and the cost of independently maintaining several viruses. We identified a genetic marker tightly associated with a major resistance-gene cluster in cucumber that conditions resistance to many potyviruses. We developed a large segregating family and revealed 5% recombination between potyvirus resistances and our genetic marker. This distance is too far to attempt map based cloning of potyvirus resistance loci in cucumber. As a
result, we are evaluating candidate genes for resistance to Zucchini Yellow Mosaic Virus in cucumber. Our long term goal is to clone this resistance locus and develop a simple genetic marker for selection.
Impacts
These experiments will allow us to determine if any candidate genes known to condition virus resistance in other plants will be useful for development of a molecular marker for ZYMV resistance in the cucurbits
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Potyviruses routinely cause significant yield and quality losses in the cucurbits (cucumber, melon, watermelon, and squash). We previously cloned and sequenced a 5-kb cucumber genomic region co-segregating with the recessive locus (zym) conditioning resistance to Zucchini Yellow Mosaic Virus (ZYMV) in cucumber. We have continued this work by fine mapping of the marker and zym locus. A recombinant inbred line heterozygous at zym was chosen and seed produced by intercrossing among these highly related plants. Individual plants were self pollinated and scored for genotypes at the marker locus linked to zym. Plants were selected that were either homozygous for the resistant (TMG1) or susceptible (Straight 8) parental alleles. The selfed progenies are being inoculated with ZYMV to identify any segregating families, which will reveal recombinant gametes between the marker and zym loci. We are also completing comparative mapping of potyvirus resistance loci in cucumber and
melon and have documented that ZYMV resistance in these two Cucumis species are conditioned by different resistance genes.
Impacts
These experiments will allow us to determine how close our molecular marker is to the ZYMV resistance locus and its utility in selecting resistant plants.
Publications
- Park, Y.H., N. Katzir, Y. Brotman, J.J. King, F. Bertrand, and M.J. Havey. 2004. Comparative mapping of ZYMV resistances in cucumber and melon. Theor. Appl. Genet. 109:707-712.
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Progress 01/01/03 to 12/31/03
Outputs
A PCR-based marker was used to select cucumber plants homozygous for the chromosome region carrying resistance to Zucchini Yellow Mosaic Virus (ZYMV). These selected plants were self pollinated and progenies are being evaluated for resistance to ZYMV to develop a fine structure map near the ZYMV resistance locus.
Impacts
These experiments will allow us to determine how close our molecular marker is to the ZYMV resistance locus and its utility in selecting resistant plants.
Publications
- No publications reported this period
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