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Title: Fine mapping implicates two immunity genes in larval resistance to the honey bee brood fungal disease, Chalkbrood

item Holloway, Beth
item Tarver, Matthew
item Rinderer, Thomas

Submitted to: Journal of Apicultural Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2013
Publication Date: 6/16/2013
Citation: Holloway, B.A., Tarver, M.R., Rinderer, T.E. 2013. Fine mapping implicates two immunity genes in larval resistance to the honey bee brood fungal disease, Chalkbrood. Journal of Apicultural Research. 52(2):134-140.

Interpretive Summary: Chalkbrood disease results from a fungal infection of the intestinal track of honey bee brood. The fungus affects the brood of stressed colonies especially during cold weather, when other pests are present, or during times of low nectar flow. Previous research has shown that bee larvae that are exposed to chalkbrood spores may actually have some genetic basis of resistance. In this study we used molecular markers on the DNA to identify regions of the genome that may be responsible for the resistance in larvae. We used this type of genetic mapping to identify a region so small that only 2 genes could possibly be the source of resistance. Because we have narrowed down the region to such a small area, we could develop a marker assisted breeding program increase chalkbrood resistance in managed colonies. Using the molecular markers we have identified, we would prescreen queen and drone bees to see if they would be able to produce colonies that have a better chance of being resistant to chalkbrood infections.

Technical Abstract: Chalkbrood infection of honey bee (Apis mellifera) brood by the fungus Ascosphaera apis results in fatal encapsulation of susceptible larvae with a mycelial coat. Recent QTL analysis indicates that some level of physiological resistance exists in individual larvae. We performed a fine mapping analysis to define the genetic interval that confers resistance in the larvae. Evaluation of the interval suggests that only two possible genes (single Ig IL-related receptor-like, XM_003251514.1 and juvenile hormome-binding protein, XM_391872.4) can be responsible for the resistance. Both genes are strong physiological candidates and potentially function as modulators of the antifungal-specific innate immunity pathway in insects.