Progress 03/22/05 to 12/31/06
Outputs
Progress Report Objectives (from AD-416) The objective of this cooperative research project is to develop the biological tools, materials, and resources necessary to allow cucumber geneticists and breeders access to genomics technologies. Approach (from AD-416) The approach to be followed is to construct genomic and expression libraries of genes and DNA fragments of cucumber, isolate relevant genes and gene fragments from these libraries, determine nucleotide sequences for these fragments, identify possible biological function(s) of genes and elements carried on these fragments, and deposit these and similar sequences in Genbank for the widest possible scientific distribution. Significant Activities that Support Special Target Populations This report serves to document research being conducted under a specific cooperative agreement between ARS and Michigan State University. Additional details can be found in the report for the parent project 3635- 43000-004-00D, Technologies for Assessing and Grading Quality and Condition of Cucumbers and Tree Fruits. Project progress was monitored via interactions with the collaborator through meetings, phone calls, and lab visits. The objective of the project was to develop tools that will build the cucumber genomics information base to facilitate future breeding efforts and genetic improvement of pickling cucumber. Sequences obtained from the cucumber fruit cDNA library were examined for possible function and compared to those previously obtained for the cucumber leaf library. Functional categories most highly represented in the ca. 1900 fruit clones, were metabolism (carbohydrate, lipid, amino acid, nucleotide, phosphate, and secondary metabolism), signaling, transcriptional regulation, and fruit associated genes. For the leaf library, the two largest groups are genes associated with photosynthesis (26%) and protein synthesis/translation (19%) as would be expected from young, growing, photosynthetically active tissue. The fruit library should be useful for analysis of gene expression changes associated with changes in fruit susceptibility to Phytophthora capsici as described below. Sequences from the fruit library have been deposited to GenBank and are also available on the MSU cucumber genomics web site (http://genomics.msu.edu/cucumberdb/). The sequence data already have been useful for development of new molecular markers for cucumber map development and breeding efforts by other researchers. Cucumber fruit rot caused by the soil-borne oomycete pathogen P. capsici, has become an increasingly important problem for pickling cucumber production. The preferred method of control would be genetic resistance, however, screening efforts to date have not identified a reproducible source of resistance. In the process of screening for fruit resistance we observed that younger fruit are more susceptible than older fruit, and that there is a marked decrease in fruit susceptibility that coincides with the end of the period of rapid fruit elongation. Observations of fruits in the field indicate that infection generally begins at the blossom end and the stem end becomes less susceptible sooner than the blossom end. Studies to investigate the basis for resistance suggest that the change in fruit susceptibility is associated with fruit surface properties. These differences in response relative to fruit age and position could allow for analysis of changes in gene expression responsible for increased fruit resistance. Progress of this project was monitored by monthly, either by e-mail for face to face meetings.
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Progress 10/01/05 to 09/30/06
Outputs
Progress Report 4d Progress report. This report serves to document research being conducted under a specific cooperative agreement between ARS and Michigan State University. Additional details of research can be found in the report for the parent CRIS 3635-43000-004-00D, Technologies for Assessing and Grading Quality and Condition of Cucumbers and Tree Fruits. Sequences obtained from the cucumber fruit cDNA library were examined for possible function and compared to those previously obtained for the cucumber leaf library. Functional categories most highly represented in the ca. 1900 fruit clones, were metabolism, signaling, transcriptional regulation, and fruit associated genes. This can be contrasted to the leaf library where photosynthesis was the dominant category, and provides confidence that the two libraries provide a good representation of the respective tissue types. The fruit library should be useful for analysis of gene expression changes associated with
changes in fruit susceptibility to Phytophtora capsici as described below. Sequences from the fruit library have been deposited to GenBank and are also available on the MSU cucumber genomics web site. Cucumber fruit rot caused by the soil-borne oomycete pathogen Phytophtora capsici, has become an increasingly important problem for pickling cucumber production. The preferred method of control would be genetic resistance, however, screening efforts to date have not identified a reproducible source of resistance. It was observed that younger fruit are more susceptible than older fruit, and that there is a marked decrease in fruit susceptibility that coincides with the end of the period of rapid fruit elongation. Observations of fruits in the field indicate that infection generally begins at the blossom end. Comparison of stem and blossom end inoculations indicated that while both ends are very susceptible in young fruits, the stem end becomes less susceptible sooner than the blossom
end. Preliminary studies suggest that the change in fruit susceptibility is associated with fruit surface properties. These differences in response relative to fruit age and position could allow for analysis of changes in gene expression responsible for increased fruit resistance and for identifying gene expression differences that may be associated with reduced susceptibility.
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Progress 10/01/04 to 09/30/05
Outputs
4d Progress report. This report serves to document research being conducted under a specific cooperative agreement between ARS and Michigan State University. Additional details can be found in the report for the parent project 3635- 43000-004-00D Technologies for Assessing and Grading Quality and Condition of Cucumbers and Tree Fruits. This cooperative project was too new to report on its research progress.
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