Sweet bell pepper is the major vegetable crop cultivated in the Arava Valley in southern Israel, covering 1,000 hectares, 60 % of which is exported. Chilling injury (CI) is a physical disorder that occurs in the early winter when temperatures drop below 4°C. Usually, the damaged bell pepper is not marketable. Due to their genetic diversity, the level of CI tolerance varies between accessions and cultivars. The most common varieties in the Arava Valley are susceptible to CI. Therefore, new high-quality cultivars CI-tolerant need to be bred. Our study objective was to unravel the genetics underlying CI and identify genetic markers, which can support breeders in selecting CI-tolerant genotypes.
Pepper fruits from 144 accessions of an F2 segregating population were chilled (2°C for 20 hours) and scored for CI tolerance, along with their two parental lines and the F1-hybrid offspring. Biochemical and physiological mechanisms have been explored on susceptible and tolerant accessions by measuring anti-oxidant activity, reactive oxygen species accumulation and the performance of metabolic profiling analysis.
With that knowledge, metabolic pathways can be mapped along with finding candidate genes that express CI tolerance. Additionally, a bulked segregant RNA-seq was performed and revealed differential expression of SNPs of candidate genes associated with CI tolerance in bell pepper. This combined approach of metabolomics and genomics has provided a better understanding of the CI tolerance mechanisms and provided several potential bio- and genetic markers which breeders can use by means of marker assisted selection.