Project Number: 6602-21000-018-00
Project Type: Appropriated

Start Date: May 22, 2003
End Date: May 21, 2008

Objective:
New (additional) objectives per PDRAM HQ 01f, June 28, 2007. (1) Screen F2 segregating populations derived from crosses between A. cardenasii-derived low-aflatoxin producing germplasm lines and high-aflatoxin producing cultivars. Use candidate AFLP markers in order to identify markers closely linked to genetic factors controlling aflatoxin accumulation; and (2) Continue hybridization and generation advance program to combine resistance to preharvest aflatoxin contamination (PAC) with acceptable yield and grade. Continue selection for resistance to PAC within segregating F5 populations; continue selection for drought tolerance within segregating F5 populations. Examine these selections for resistance to PAC in subsequent generations. Attempt to identify other characteristics that may serve as indirect selection tools for resistance to PAC. Assess the use of nematode resistance cultivars to reduce PAC in peanut. Select a core of the core collection for the U.S. germplasm collection of peanut and determine if it can be used to improve the efficiency of mining valuable genes from the entire collection. Develop peanut germplasm with resistance to preharvest aflatoxin contamination. Develop germplasm with resistance to the peanut root-knot nematode and tomato spotted wilt virus. Develop efficient and useful techniques to identify resistance to drought in peanut, and use them to characterize germplasm for resistance.

Approach:
Multivariate statistical analysis of morphological data will be used to group accessions, and random sampling will then be used to select a core of the core collection. Disease resistance data will be used to determine if a core of the core can be used to improve utilization of germplasm collections. Breeding populations will be developed by hybridizing high yielding cultivars with sources of resistance to preharvest aflatoxin contamination, and sources of improved drought tolerance. These populations will be evaluated under field conditions with drouht and heat stress imposed by covering the entire test area with a mobile greenhouse. Drought stress and pod yields will be measured and aflatoxin contamination will be determined using the immunoaffinity column fluorometer method. Breeding populations will also be developed by hybridizing sources of resistance to the peanut root-knot nematode and tomato spotted wilt virus. These populations will be tested for resistance to nematodes using the greenhouse screening technique. Progenies exhibiting nematode resistance will then be field tested for virus resistance.