Abstract
Chromosome segment substitution lines (CSSLs) are powerful QTL mapping populations that have been used to elucidate the molecular basis of interesting traits of wild species. Cultivated peanut is an allotetraploid with limited genetic diversity. Capturing the genetic diversity from peanut wild relatives is an important objective in many peanut breeding programs. In this study, we used a marker-assisted backcrossing strategy to produce a population of 122 CSSLs from the cross between the wild synthetic allotetraploid (A. ipaënsis×A. duranensis)4x and the cultivated Fleur11 variety. The 122 CSSLs offered a broad coverage of the peanut genome, with target wild chromosome segments averaging 39.2 cM in length. As a demonstration of the utility of these lines, four traits were evaluated in a subset of 80 CSSLs. A total of 28 lines showed significant differences from Fleur11. The line×trait significant associations were assigned to 42 QTLs: 14 for plant growth habit, 15 for height of the main stem, 12 for plant spread and one for flower color. Among the 42 QTLs, 37 were assigned to genomic regions and three QTL positions were considered putative. One important finding arising from this QTL analysis is that peanut growth habit is a complex trait that is governed by several QTLs with different effects. The CSSL population developed in this study has proved efficient for deciphering the molecular basis of trait variations and will be useful to the peanut scientific community for future QTL mapping studies.
Highlights
Wild relatives of crop plants are sources of useful agriculturally interesting traits that can be tapped to improve the cultivated species [1,2]
Population Development The F1 hybrids between the cultivated Fleur11 variety and the synthetic wild allotetraploid (A. ipaensis KG300766A. duranensis V14167)4x exhibited a good level of fertility
The short duration between sowing and flowering required us to limit the number of individuals to be genotyped per backcross family at each generation
Summary
Wild relatives of crop plants are sources of useful agriculturally interesting traits that can be tapped to improve the cultivated species [1,2]. The development of interspecific introgression line (IL) libraries monitored by molecular markers allows the representation of the entire wild species genome in a set of lines each of which carries one or few wild donor segments in the genetic background of a cultivated species [3,5]. These lines are especially useful for mapping complex traits, as they are permanent populations that can be phenotyped in several environments. The introgression lines are useful starting points for breeding [2] and for mapping genes underlying QTLs [6,8]
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