Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2007
Publication Date: 9/1/2007
Citation: Zhang, L., Mojtahedi, H., Kuang, H., Baker, B.J., Brown, C.R. 2007. The Use of STS Markers in the Marker-assisted Selection of Columbia Root-knot Nematode Resistance Introgressed from Solanum bulbocastanum. Crop Science. 47:2021-2026. Interpretive Summary: The Columbia root-knot nematode causes severe damages to potato tubers. This nematode is traditionally controlled with soil fumigants and crop rotation. A gene controlling resistance derived from a Mexican wild species has been identified and used in breeding resistant germplasm. It is time consuming to introgress a resistance gene into advanced breeding populations by means of traditional breeding technique. Therefore, DNA markers linked to resistant genes could be used to track resistance introgression among a set of diverse breeding lines. This study showed that it is possible to use sequence information from conserved DNA regions of known resistance genes to identify candidate markers. Marker-assisted selection is a rapid and efficient approach not only for detecting the resistance gene at very early seedling stages for introgression purposes, but also for cloning the gene resistance to the Columbia root-knot nematode. These closely linked molecular markers should facilitate to select resistant lines for managing the nematode on potatoes. Furthermore, these new PCR-based markers have provided an efficient and rapid alternative for greenhouse screening of a large potato breeding population.
Technical Abstract: The Columbia root-knot nematode (Meloidogyne chitwoodi) (CRN) is a serious pest that reduces tuber quality of potato in the Northwest of the US and other parts of the World. A gene, RMc1(blb), derived from the Mexican wild species Solanum bulbocastanum, controls resistance to this pest. A F1 mapping population with over 250 individuals generated from an intraspecific cross between resistant and susceptible clones of S. bulbocastanum, SB22 and PT29 was used for marker screening and genetic linkage analysis. Two AFLP markers and two CAPS markers were localized close to the gene with 0, 0.5, 2.4 and 4.3 cM genetic distance, respectively. In addition to these four markers, five new Sequence Tagged Site (STS) markers developed from BAC-end sequences derived from a library derived from another species, S. demissium, (selected originally by having homology to the N gene like sequences from tobacco) co-segregated with the RMc1(blb). These markers were tested on backcross five families that were part of the introgression of RMc1(blb) into advanced breeding lines in the BC5, and its utility for an efficient alternative to greenhouse and field phenotypic screening was demonstrated. The results of this study confirm that closely linked molecular markers to RMc1(blb ) will assist in a selection program, reducing expense and time involved in root-knot nematode screening.