Imaged-Based Phenotyping Accelerated Qtl Mapping And Qtl X Environment Interaction Analysis Of Testa Colour In Peanut (Arachis Hypogaea)

To explore the genetic mechanism underlying testa colour in peanut, three-dimensional parameters, red (R), green (G) and blue (B) values were applied to define this trait. Image-based phenotypic data of a recombinant inbred line population were collected from three environments and mostly exhibited continuous distributions and transgressive segregations. Significant and positive correlations, detected among RGB values and their broad-sense heritabilities were 0.84, 0.94 and 0.87, respectively. Based on a previous high-density genetic map, quantitative trait locus (QTL) mapping was performed. Individual environmental analysis yielded eight associated QTLs, explaining phenotypic variation from 3.29% to 35.94%. A stable and consistent region detected for R and G values was identified, covering a genomic region of 116.78-118.94 Mb on chromosome 3. Multi-environmental joint analysis identified 12 additive QTLs, with phenotypic variation explained (PVE) of 1.88%-34.65%. A total of 23 pairs of epistatic QTLs involving 30 loci were identified to regulate the RGB values of testa colour. Functional annotations facilitated mining the candidate genes for testa colour in the consistent QTL region.