Effects of charcoal rot on soybean seed composition in soybean genotypes that differ in charcoal rot resistance under irrigated and non-irrigated conditions

Authors: Bellaloui, Nacer; Mengistu, Alemu; Smith, James - Rusty; Abbas, Hamed; ACCINELLI, CESARE - University Of Bologna, Italy; SHIER, THOMAS - University Of Minnesota

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2021
Publication Date: 8/29/2021
Citation: Bellaloui, N., Mengistu, A., Smith, J.R., Abbas, H.K., Accinelli, C., Shier, T.W. 2021. Effects of charcoal rot on soybean seed composition in soybean genotypes that differ in charcoal rot resistance under irrigated and non-irrigated conditions. Plants. 10(9):1801. https://doi.org/10.3390/plants10091801.
DOI: https://doi.org/10.3390/plants10091801

Interpretive Summary: Charcoal rot is a major disease of soybean and results in significant loss in yield and seed quality. The disease is a problem in the southern soybean regions of the USA and throughout the world causing reduction in yield of 10-50% and loss of seed quality. The effects of charcoal rot on seed composition (seed protein, oil, and fatty acids), a component of seed quality, is not well understood. Therefore, the objective of this research was to investigate the impact of charcoal rot on seed protein, oil, and fatty acids in different soybean genotypes differing in their charcoal rot susceptibility under irrigated and non-irrigated conditions. Two field experiments were conducted in 2012 and 2013 in Jackson, TN, USA. Thirteen genotypes differing in charcoal rot resistance (moderately resistant and susceptible) were evaluated. The results showed that under non-irrigated conditions, moderately resistant genotypes showed either no change or increased protein and increased oleic acid, but had lower linolenic acid. Under non-irrigated conditions, most of the susceptible genotypes showed lower protein and linolenic acid, but higher oleic acid. Most of the moderately resistant genotypes had higher protein than susceptible genotypes under irrigated and non-irrigated conditions, but lower oil than susceptible genotypes. The different responses among genotypes for protein, oil, oleic acid, and linolenic acid observed in each year may be due to both genotype and environmental conditions, especially heat differences in each year (2012 was warmer than 2013). This research showed that the increases of protein and oleic acid, and the decrease of linolenic acid could be a possible mechanism underlying the plant’s responses to the charcoal rot infection. This research further helps scientists understand the impact of irrigated and non-irrigated conditions on seed nutrition changes using resistant and susceptible genotypes. Soybean varieties with moderate resistance to charcoal rot may maintain normal levels of seed oil and protein when plants are grown in fields infested with charcoal rot disease.

Technical Abstract: Charcoal rot is a major disease of soybean [(Glycine max (L.)] caused by Macrophomina phaseolina and results in significant loss in yield and seed quality. The effects of charcoal rot on seed composition (seed protein, oil, and fatty acids), a component of seed quality, is not well understood. Therefore, the objective of this research was to investigate the impact of charcoal rot on seed protein, oil, and fatty acids in different soybean genotypes differing in their charcoal rot susceptibility under irrigated and non-irrigated conditions. Two field experiments were conducted in 2012 and 2013 in Jackson, TN, USA. Thirteen genotypes differing in charcoal rot resistance (moderately resistant and susceptible) were evaluated. Under non-irrigated conditions, moderately resistant genotypes showed either no change or increased protein and increased oleic acid, but had lower linolenic acid. Under non-irrigated conditions, most of the susceptible genotypes showed lower protein and linolenic acid, but higher oleic acid. Most of the moderately resistant genotypes had higher protein than susceptible genotypes under irrigated and non-irrigated conditions, but lower oil than susceptible genotypes. The different responses among genotypes for protein, oil, oleic acid, and linolenic acid observed in each year may be due to both genotype and environmental conditions, especially heat differences in each year (2012 was warmer than 2013). This research showed that the increases in protein and oleic acid, and the decrease in linolenic acid could be a possible physiological mechanism underlying the plant’s responses to the charcoal rot infection. This research further helps scientists understand the impact of irrigated and non-irrigated conditions on seed nutrition changes using resistant and susceptible genotypes.