Comparison of gene expression profiles in cultivated peanut (Arachis hypogaea) under strong artificial selection

With 9 figures and 1 table Abstract Over the past five decades, cultivated peanut in China has been subjected to strong artificial selection in breeding programmes. To investigate the impact of artificial selection on expression diversity, we compared gene expression profiles in pod and leaf of five widespread cultivars in Southern China. In terms of tissues, hierarchical clustering analysis revealed that expression data of pod and leaf generated different dendrograms owing to artificial selection. K-means analysis also showed that there were 16 gene expression patterns in leaf, while only eight in pod. In considering cultivars, a cultivar specificity index (t) was employed to characterize expression patterns, which suggested that genes having 0.15 < t < 0.85 constituted >80% of all expression patterns. Additionally, the diversity of gene expression in pod among cultivars of the YY7 pedigree decreased from 23.8% to 3.9%. Taken together, nucleotide polymorphisms in regulatory elements owing to artificial selection led to low-expression polymorphisms in both tissues and cultivars, contributed to the narrow genetic diversity and might be a driving force behind the breeding of cultivated peanut.