Abstract: 【Objective】The objective of this study is to explore the potential loci for resistance to late blight of introgression line (IL) population derived from a nightshade related species Solanum lycopersicoides LA2951. 【Method】 Detached-leaflet assay (DLA) was used for the artificial inoculation. The abaxial surface of each leaflet was inoculated with a drop of 10 μL sporangial suspension (2×104 sporangiums/mL), and the inoculated leaves were incubated at 19℃ with 70%-100% relative humidity. Lesion size (LS) of the leaf and disease incidence (DI) were measured 6 d after inoculation.【Result】The resistance of this wild species was controlled by quantitative trait loci (QTL). In total, 5 QTLs (Rpiq1b, Rpiq2b, Rpiq4b, Rpiq8a, Rpiq11) were identified after inoculation with race T1,2, which significantly reduced LS, and 3 QTLs (Rpiq1a, Rpiq2a, Rpiq8b) were indentified which clearly reduced DI. However, only 2 QTLs (Rpiq4a and Rpiq5) reducing DI were indentified after inoculation with more virulent race T1,2,4. It proved that QTLs derived from LA2951 showed a clear race-specific resistance. Based on tomato high density genetic linkage map, all QTLs detected in this paper were co-localized with those previously identified in other tomato wild species. In addition, 2 susceptibility QTLs (Spiq4 and Spiq10) increasing DI were identified after inoculation with both race T1,2 and race T1,2,4, which were located at the end of short arm of chromosome 4 and chromosome 10, respectively. 【Conclusion】Ten resistance QTLs and 2 susceptibility QTLs were identified, and they presented a race-specific behavior. The results obtained in this paper provided a theoretical basis for breeding of late blight resistance in tomato.

Key words: Solanum lycopersicoides, introgression line, late blight, quantitative trait loci