Andean common bean bulk breeding lines selected in Tanzania, South Africa, Puerto Rico and Washington State exhibit broad genetic diversity and stress adaptation

Authors: SADOHARA, R - Michigan State University; Cichy, Karen; FOURIE, D - Dry Bean Producers Organization; NCHIMBI MSOLLA, S - Sokoine University Of Agriculture; Song, Qijian; Miklas, Phillip - Phil; Porch, Timothy - Tim

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Phaseolus Improvement Cooperative (PIC) population was developed using bulk breeding as a collaborative effort to improve abiotic stress tolerance, particularly drought, of the Andean germplasm of common bean. Fifty-two Andean and five Middle American genotypes were selected as parents and inter-crossed. The resulting breeding populations were grown in South Africa, Tanzania, Puerto Rico, and Washington and 384 lines were selected for further evaluation based on superior agronomic performance. DNA markers were evaluated on all the selected lines and the parental genotypes used in hybridizations. DNA information was used to estimate genetic diversity and genomic regions important for agronomic performance. Among the parental genotypes, NY 105 (US), Mrondo (Tanzania), AC Elk (Canada), and TARS-HT1 (Puerto Rico) were the most represented in selected PIC lines. Subsets of the PIC lines were grown in Puerto Rico in 2019 (n=288) and 2020 (n=176) to evaluate productivity under drought stress. Seed yield ranged from 31–388 kg/ha in 2019 and 169–1762 kg/ha in 2020. This study combined the use of bulk breeding of dry beans in multiple locations to assess genetic diversity, identify highly represented parental genotypes, evaluate yield performance under drought, and identify genomic regions associated with agronomic traits. This study shows the benefit of germplasm and population exchange across continents for collaborative improvement of common bean diversity, productivity, and stress resilience.

Technical Abstract: Phaseolus Improvement Cooperative (PIC) populations were developed by crossing 52 Andean and five Middle American parental lines, most of which were from the Andean Diversity Panel, using the bulk breeding method. The progeny lines were selected and evaluated in Puerto Rico, South Africa, Tanzania, and Washington state, resulting in 384 superior PIC lines used in subsequent studies. The PIC lines and their parents were genotyped by using the common bean 12K SNP chip, which yielded 2,334 high quality SNPs. Population structure analyses indicated the strongest separation between heat tolerant landrace Indeterminate Jamacia Red (IJR) (ADP-0683)-derived PIC lines and a group of lines derived from North American parents. The PIC lines and parents were grown under water stress in Puerto Rico in 2019 (n=288) and 2020 (n=176) to assess agronomic traits including seed yield. The BLUPs (best linear unbiased predictions) for seed yield ranged from 31–388 kg ha-1 in 2019 and 169–1762 kg ha-1 in 2020. Almost all the PIC lines matched or outperformed the parents in 2019, showing the utility of crossing lines from various origins. Canopy temperatures, plant height, and reflectance measurements were taken using a proximal sensing cart in 2019, but the predictability of yield from those measurements were low. Genome-wide association analysis identified SNPs associated with yield under drought stress at 44.2 Mb on Pv10, that did not coincide with other phenology QTNs, which could inform further GWAS studies for yield and drought tolerance. Overall, the PIC populations were useful for improving genetic diversity and agronomic performance of Andean beans under suboptimal environments.