Genetic mapping identifies loci that influence tomato resistance against Colorado potato beetles

Authors: VARGAS-ORTIZ, ERANDI - Boyce Thompson Institute; GONDA, ITAY - Boyce Thompson Institute; SMEDA, JOHN - Cornell University; MUTSCHLER, MARTHA - Cornell University; Giovannoni, James; JANDER, GEORG - Boyce Thompson Institute

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/21/2018
Publication Date: 5/9/2018
Citation: Vargas-Ortiz, E., Gonda, I., Smeda, J., Mutschler, M., Giovannoni, J.J., Jander, G. 2018. Genetic mapping identifies loci that influence tomato resistance against Colorado potato beetles. Scientific Reports. 8:7429.

Interpretive Summary: The Colorado potato beetle (CPB) has become the most important insect pest on cultivated potato. Both adult beetles and larvae feed on potato leaves. A CPB female can lay around 3,000 eggs in a three-month lifespan and larvae feed for about 20 days on their host plants where they can completely destroy a potato crop. Moreover, CPB readily develops insecticide resistance and resistant CPB populations are spreading rapidly through potato-growing regions of the United States. Although CPB is mainly a pest on potato, it also can feed and complete its life cycle on other plants including eggplant and tomato. CPB has been shown to reduce tomato production in the field with young plants being the most severely affected. Furthermore, CPB has the potential to become better-adapted to tomato and thus become a more severe tomato pest. Here we demonstrate that wild tomato species carry genes that can confer resistance to CPB and thus serve as a resource for breeding more tolerant tomato lines in addition to tools for better understanding this insect pest.

Technical Abstract: The Colorado potato beetle (CPB), the most economically important insect pest on potato, also feeds on other crops including cultivated tomato. We used tomato genetic mapping populations to investigate natural variation in CPB resistance. CPB bioassays with 74 tomato lines carrying introgressions of Solanum pennellii in S. lycopersicum cv. M82 identified introgressions from S. pennellii on chromosomes 1 and 6 conferring CPB susceptibility, whereas introgressions on chromosomes 1, 8 and 10 conferred higher resistance. Mapping of CPB resistance using 113 recombinant inbred lines derived from a cross between S. lycopersicum cv UC-204B and Solanum galapagense identified significant quantitative trait loci on chromosomes 6 and 8. In each case, the S. galapagense alleles were associated with lower leaf damage and reduced larval growth. Results of both genetic mapping approaches converged on the same region of chromosome 6, which may have important functions in tomato defense against CPB herbivory.