| Abstract Detail
Conference Wide Kole, Chitta [1], Ashrafi, Hamid [2], Lin, Guoyang [1], Foolad, Majid [2]. Identification and Molecular Mapping of a New R-Gene, Ph-4, Conferring Resistance to Late Blight in Tomato. LATE blight (LB), caused by the Oomycete Phytophthora infestans, is a devastating disease in two closely related solanaceous crops, tomato and potato. The cultivated species of tomato, Lycopersicon esculentum, is highly susceptible to LB. However, sources of genetic resistance have been identified within the related wild species, in particular L. pimpinellifolium and L. hirsutum. Previously, 3 dominant or partially dominant resistant (R) genes, Ph-1, Ph-2 and Ph-3, conferring race-specific resistance were identified and mapped on tomato chromosomes. While new P. infestans races have overcome Ph-1 gene and Ph-2 provides only partial resistance to several isolates, Ph-3 confers strong resistance. However, some recent P. infestans races have emerged which also overcome Ph-3 gene. Thus, identification and pyramiding of new resistance genes or QTLs through marker-assisted introgression is imperative. We have developed a recombinant inbred line (RIL) population of tomato from a L. esculentum × L. pimpinellifolium cross for various purposes including mapping of early blight resistance QTLs. A saturated molecular map of this population was also constructed. During the summer of 2004 we determined that the early-blight-resistant parent (L. pimpinellifolium) of this RIL population was also resistant to several isolates of P. infestans. Further screening of this population for late blight resistance in the greenhouse during the past two years has resulted in the identification and mapping of a new resistance gene (Ph-4) on tomato chromosome 2. In addition to the identification of this locus, QTL analysis detected a few other chromosomal locations with effects on the degree of resistance. The detailed screening and mapping procedure of this new LB resistance gene and implications of its use in marker-aided gene-pyramiding to develop durably late blight resistant tomatoes will be discussed.
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1 - The Pennsylvania State University, Department of Horticulture, 103 Tyson Building, University Park, PA, 16802-4200, USA
2 - The Pennsylvania State University, Department of Horticulture and The Inter-college Graduate Degree Program in Genetics, 103 Tyson Building, University Park, PA, 16802-4200, USA
Keywords:
Late Blight
QTL mapping
Phytophthora infestans
Recombinant Inbred Line
Lycopersicon esculentum.
Session: Poster-163
Location: Ballroom CD/Monona Terrace
Date: Tuesday, July 25th, 2006
Time: 8:00 AM
Abstract ID:449 |
