Soybean pod shattering resistance allele pdh1 and marker-assisted selection

Authors: SHIMBWAMBWA, DORA - University Of Zambia; NACHILIMA, CHRISTABEL - International Institute Of Tropical Agriculture (IITA); HAMABWE, SWIVIA - University Of Zambia; KUWABO, KUWABOO - University Of Zambia; CHIGEZA, GODFREE - International Institute For Tropical Agriculture; Bilyeu, Kristin; KAMFWA, KELVIN - University Of Zambia

Submitted to: Plant-Environment Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/29/2024
Publication Date: 8/12/2024
Citation: Shimbwambwa, D., Nachilima, C., Hamabwe, S., Kuwabo, K., Chigeza, G., Bilyeu, K.D., Kamfwa, K. 2024. Soybean pod shattering resistance allele pdh1 and marker-assisted selection. Plant Breeding. 5(4). https://doi.org/10.1002/pei3.70003.
DOI: https://doi.org/10.1002/pei3.70003

Interpretive Summary: Loss of seed yield due to pod shatter is a major problem in some production environments. The conditions leading to pod shatter are inconsistent in different environments and make the trait a difficult one for breeding improvement. One major gene controlling pod shatter in soybean was identified, and the frequency of the shatter susceptible allele was initially found to be almost 25% in African soybean germplasm. The objective of this work was to investigate 59 newer soybean germplasm lines from the IITA soybean breeding program for both pod shattering resistance in field studies and the status of the major pod shattering gene. The results showed all but two of the lines carried the resistant form of the pod shattering gene, and those two lines had significantly higher pod shatter scores than the lines carrying the resistant form of the gene. There were other differences in pod shatter resistance that were detected for some germplasm that could be used as parents in the breeding program. The impact of this work is that informed choice of parent lines or continued use of the pod shatter molecular marker in the breeding program will improve soybean yields by reducing pod shattering in newly developed cultivars.

Technical Abstract: Pod shattering is a major production constraint of soybean [Glycine max (L.)]. The objectives of this study were to (i) estimate heritability for pod shattering resistance, (ii) determine the frequency of the pod shattering resistance allele pdh1 in the International Institute for Tropical Agriculture (IITA) soybean germplasm and Zambian commercial varieties, and (iii) determine the effectiveness of the DNA marker for the pod shattering resistance allele pdh1. A total of 59 genotypes were evaluated for pod shattering in field trials conducted in Malawi and Zambia, and genotyped with a marker for pdh1. TGx2002-8FM and TGx2002-9FM were the most resistant among genotypes in early and medium maturity classes, and can be used for genetic enhancement of pod shattering resistance in these specific maturity classes. Narrow sense heritability estimates for pod shattering ranged from 0.27 – 0.80. Of the 59 genotypes, 57 (96.6%) carried the resistance allele pdh1 while only two genotypes (3.6%) carried the susceptible allele, suggesting near-fixation of the resistance allele pdh1 in the IITA germplasm. The marker for pdh1 was highly effective in selecting resistant genotypes.