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Name: Ye Chu (Juliet)
Pyramiding nematode resistance and high O/L traits in elite peanut cultivars using marker assisted selection
Y. Chu, P. Ozias-Akins Department of Horticulture, The University of Georgia, Tifton Campus, GA 31793-0748, C. C. Holbrook, USDA-ARS, Tifton, GA 31793
In order to integrate nematode resistance and high oleic acid to linoleic acid ratio (high O/L) traits into elite cultivars, and in particular to derive a high O/L ‘Tifguard’, hybrid F1s from Tifguard x Georgia-02C (C1804) and Tifguard x Florida-07 (C1805) were used as male parents to cross with a number of cultivars. ‘Tifguard’ has a high level of resistance to root-knot nematode while ‘Georgia-02C’ and ‘Florida-07’ are high O/L. Molecular markers for both traits were used to identify heterozygotes among F1 progenies. A total of 150 F1 progenies were produced from the proposed crosses, and 35 F1 hybrids carrying the most ideal trait combinations were selected for further crosses using the same set of cultivars as female parents. A total of 213 potentially hybrid pods was produced. We are on track to meet the objective to produce high oleic Tifguard by June 2010. Markers were also applied to F2 populations of C1804 and C1805 to identify 45 homozygotes for both nematode resistance and high O/L so that further screening can more efficiently focus on disease resistance traits. Four peanut cultivar/germplasm lines with drought tolerance and aflatoxin resistance were crossed with Tifguard and 382 F2 plants homozygous for nematode resistance were identified among 1581 F2 plants. During the breeding project, nematode resistance markers were also used to check the purity of Tifguard from various lots. The use of molecular markers for only two traits has greatly accelerated the conversion of a nematode resistant elite line to high O/L as well as the transfer of nematode resistance to improved germplasm.