QTL Mapping of Post-Processing Color Retention in Two Black Bean Populations

Authors: BORNOWSKI, NOLAN - Michigan State University; Song, Qijian; KELLY, JAMES - Michigan State University

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2020
Publication Date: 7/27/2020
Citation: Bornowski, N., Song, Q., Kelly, J. 2020. QTL Mapping of Post-Processing Color Retention in Two Black Bean Populations. Theoretical and Applied Genetics. https://doi.org/10.1007/s00122-020-03656-3.
DOI: https://doi.org/10.1007/s00122-020-03656-3

Interpretive Summary: In the United States and other minority-world countries, many consumers eat common beans as already-prepared canned products. The canned product is long-lasting, portable, and convenient for many consumers seeking to minimize food preparation time. Unfortunately, when black beans are hydrothermally processed prior to consumption, water-soluble anthocyanins are released from the seed coat, resulting in an undesirable faded brown color in the cooked product. Breeding for color retention and other canning quality traits is a time- and resource- intensive endeavor that involves generations of inbreeding and specialized equipment. DNA technology may speed this process. In this study, we developed a novel and comprehensive method of measuring canned beans color via digital image analysis which eliminated many confounding factors like high reflectance, small sample size, and panel ratings. We also developed a black bean seed population and found DNA genetic regions linked to post-processing color retention in black beans. The results and methods described in this study will be useful for dry bean breeders and food scientists to produce high quality black beans with genetically superior color retention following canning and to meet consumer needs.

Technical Abstract: When black beans are hydrothermally processed prior to consumption, water-soluble anthocyanins are released from the seed coat, resulting in an undesirable faded brown color in the cooked product. The aim of this research was to develop mapping populations with different genetic sources of color retention in order to identify regions of the dry bean genome associated with canning quality traits. Two half-sibling black bean recombinant inbred line (RIL) populations segregating for post-processing color retention were developed. These RIL populations were phenotyped for canning quality traits over two years and genotyped using the BARCBean6k_3 BeadChip. In addition to traditional phenotyping by trained panelists, cooked beans were also phenotyped using a novel digital image analysis pipeline. Measurements of post-processing seed coat color from both phenotyping methods were compared and the digital image analysis was shown to outperform the trained panelists. Quantitative trait loci (QTL) for post-processing color retention were detected on six chromosomes, with QTL on Pv08 and Pv11 consistently detected across phenotyping methods, populations, and years. Color retention QTL on Pv08 explained up to 32% of phenotypic variation but were significant over a large physical interval due to low SNP marker coverage. However, color retention QTL on Pv11 also explained a substantial amount of phenotypic variation (R2 ˜ 25%) and mapped to a small genomic region near 52.5 Mbp. The QTL and methods described in this study will be useful for dry bean breeders and food scientists to produce high quality black beans that meet consumer needs.