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Agricultural Research Service United States Department of Agriculture
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Research Project: IDENTIFICATION OF MOLECULAR MARKERS LINKED TO RESISTANCE TO VSD, PHYTOPHTHORA POD ROT (PRR), LONGICORN (TRUNK BORER) IN PNG.

Location: Miami, Florida

2007 Annual Report


1a.Objectives (from AD-416)
Identify molecular markers linked to resistance to VSD, Phythophthora pod rot (Ppr), Longicorn (trunk borer), productivity, vigor and quality by developing appropriate families to locate these markers. A linkage map will be developed using the 500 progeny from the cross K82 x KA2-101. We will attempt to associate the molecular makers with quantitative trait loci (QTL) that should be detected for disease resistance, quality and productivity.


1b.Approach (from AD-416)
The parents used in this study have been developed in Papua New Guinea (PNG) and used as parents for the SG2 hybrid developed by the Cocoa and Coconut Institute (CCI). Both clones are Trinitario. K82 has relatively low vigor and produces green pods with light reddish patches. It is resistant to black pod disease (Ppr) and Fish Bone Disorder (FBD) probably caused by Colletotrichum, but susceptible to VSD and Longicorn. KA2-101 is a more vigorous clone producing dark red pods. It is resistant to VSD and Longicorn, but susceptible to Ppr and FBD. The production of full-sibs from these parents gives the unique opportunity to study the segregation pattern of genes associated with resistance for both these diseases and will provide information on the interaction of resistance genes for different pathogens.


3.Progress Report
This report serves to document research conducted under a specific cooperative agreement between ARS and Cocoa and Coconut Institute of PNG. Additional details of research can be found in the report for the parent project 6631-21000-012-00D Development of DNA markers associated with disease resistance in cacao.

A large mapping population segregating for resistance to BP, VSD, and Longicorn trunk borer was produced and planted in the field in 2004. Disease ratings were taken in 2005 and 2006 for BP and VSD. In late 2006 cocoa pod borer was found in PNG and the plants were striped of leaves along with all other breeding plots to try to eradicate the pest. The plants have now recovered and data will be taken again in 2008. The plants will be evaluated for quality and productivity traits, once fruit are produced. Over 80 microsatellite markers have been run on the population, and a map is expected within the next year, using an additional 150 markers. The identification of QTL for BP and VSD will enhance the Marker Assisted Selection program. This information is critical to the success of the overall genetic improvement program based at the USDA station in Miami.

Monitoring Activities: A site visit to cooperator's experimental field plots is planned in September 2007.


   

 
Project Team
Schnell, Raymond - Ray
 
Project Annual Reports
  FY 2008
  FY 2007
  FY 2006
 
Related National Programs
  Plant Genetic Resources, Genomics and Genetic Improvement (301)
 
 
Last Modified: 11/07/2008
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