BSA‑seq and genetic mapping reveals AhRt2 as a candidate gene responsible for red testa of peanut

Testa color is an important trait of peanut (Arachis hypogaea L.). Peanuts with red testa are rich in anthocyanin, are very popular with consumers. However, genes responsible for the red testa trait in peanut are rarely reported. In order to fine map red testa gene, two F4 populations were constructed through the cross of YZ9102 (pink testa) with ZH12 (red testa) and Zhanhong2 (red testa). Genetic analysis indicated that red testa was controlled by a single recessive gene, and named as AhRt2 (Red testa gene 2). Using BSA-seq approach, AhRt2 was preliminary identified in chromosome 12, and further mapped to a 530-kb interval using 220 recombinant lines through linkage mapping. Functional annotation, expression profiling, and sequence variation analyses confirmed that the anthocyanin reductase (ANR), Arahy.IK60LM, was the most likely candidate gene for AhRt2. A SNP in the third exon of AhRt2 changed the encoding amino acids, was associated with red testa of peanut. In addition, a closely linkaged molecular marker to red testa trait was developed. Our result provide insight into the molecular mechanism underlying peanut testa color and provide valuable diagnostic marker for marker-assisted selected (MAS) breeding in peanut.