Identification of Candidate Genes for Mummy Berry Disease Resistance in Blueberry

With an increasing consumer focus on healthy eating habits and antioxidant intake, blueberries are steadily rising in production and sales, and by consequence, are also increasing in the amount of agricultural land they occupy.

One of the most devastating diseases of blueberry in the U.S. is mummy berry. The causal fungus of the disease is Monilinia vaccinii-corymbosi. Crop loss due to mummy berry has been reported repeatedly from 1960s until now. In 2002 in no-spray rabbiteye blueberry fields in North Carolina, 70-80% of crop loss was reported. Current methods for controlling the disease include cultural practices and chemical controls. Developing resistant cultivars reduces the cost of fungicide application(s) and is an environmentally friendly measure to control the disease.

To identify genes that are differentially expressed in response to the disease, we used an infected and an uninfected susceptible blueberry cultivar, Arlen, for gene expression analysis in response to the mummy berry pathogen. A total of 16 RNA-Seq libraries of various tissues were constructed and 24 million raw Illumina reads (150 bases long, single-end) equivalent to 3.6 Gb of nucleotides were generated. The reads were mapped to the blueberry reference genome to identify differentially expressed genes and a genome-guided transcriptome assembly of blueberry was made. The implication of leveraging RNA-Seq technology in the identification of differentially expressed genes will be discussed. This will lead to the development of molecular markers that can be used in marker assisted selections for genomic selection and new cultivar development.