Identification and mapping of late blight resistance QTLs in the wild tomato accession PI 224710 ().

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Late blight (LB), caused by oomycete , is one of the most destructive diseases of the cultivated tomato, . Since new and aggressive clonal lineages of , many of which overcoming formerly effective fungicides or host resistance genes, have continued to emerge, it is crucial to identify, characterize, and utilize new sources of host resistance in tomato breeding. A recent screening of tomato germplasm identified accession PI 224710 with very strong resistance to several current clonal lineages. The present study aimed to identify and characterize QTLs associated with LB resistance in PI 224710. Disease screening of a large F population ( = 1721), derived from a cross between PI 224710 and LB-susceptible tomato breeding line Fla. 8059, followed by F progeny testing, resulted in the identification of 43 highly-resistant and 27 highly-susceptible F individuals. A selective genotyping approach, using 469 non-identical SNP markers, resulted in the construction of a genetic linkage map and identification of three LB-resistance QTLs on chromosomes 6, 9 and 10 of PI 224710. A comparison of the QTLs genomic locations with the tomato physical map resulted in the identification of several candidate genes, which might be underpinning the LB-resistance QTLs in PI 224710. The identified markers associated with the LB-resistance QTLs can be utilized in breeding programs to transfer resistance from PI 224710 into tomato breeding lines and hybrid cultivars via marker-assisted breeding; they also can be used to develop near-isogenic lines for fine mapping of the QTLs.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11032-024-01498-1.