Research
Nutrient Profiling of Tropical Soybean (Glycine Max) Core Collection
Soybean (Glycine max (L.) Merrill) is a highly nutritious legume with enormous potential to improve dietary quality for humans and livestock. However, the development of varieties with improved nutritional traits has been affected by the negative correlation that exists among the different traits and the high cost of the phenotypic assessment. The objectives of this study were: (1) to quantify the total protein, total oil and fatty acids of 52 soybean genotypes from different sources, (2) to identify correlations among total protein, total oil content and fatty acids. The total protein content was determined using the Modified Folin-Lowry Method. In contrast, the total oil and fatty acids methyl esters were determined using the chloroform/methanol gravimetric method and Gas Chromatography–Mass Spectrometry. The analysis of variance revealed that the studied traits varied significantly depending on genotypes and origin. Total protein content ranged from 30.07% to 50.40 %, while total oil content ranged from 14.94% to 23.48%. Total oil content varied significantly between origins with genotypes from the USA having the highest mean of 20.43%, while those from AVRDC had the lowest mean of 18.32 %. Palmitic acid (16:0) content ranged from 10.58% to 21.18%; 4.93% to 22.20% for stearic acid (18:0), 22.69% to 39.95% for oleic acid (18:1) and 30.60% to 51.72 % for linoleic acid (18:2). Genotypes from Uganda had the highest percentages of oleic acid, followed by genotypes from Japan. Six negative and three positive correlations were found to be significant in the current study further. The current study identified soybean genotypes with elevated protein and oil content above the average that can be used to improve the nutritional properties of soybean in Uganda and across the East African region hence boosting the soybean industry.
Genetic Diversity and Population Structure Analysis of Tropical Soybean (Glycine max (L.) Merrill) using Single Nucleotide Polymorphic Markers
Soybean (Glycine max (L.) Merrill) is among the most important crops worldwide due to its numerous uses in feed, food, biofuel, and significant atmospheric nitrogen fixation capability. To understand the genetic diversity and population structure of tropical soybean germplasm, 89 genotypes from diverse sources were analyzed using 7,962 SNP markers. The AMOVA results showed low diversity among and high within the populations, while the polymorphism information content (PIC) was 0.27. Both phylogenetic and principal component analysis grouped the 89 soybean genotypes into three major clusters, while population structure grouped the soybean genotypes into two subpopulations. On the other, the average Roger genetic distances within the study population was 0.34.The low diversity reported in the studied soybean germplasm pool is particularly worrying, considering the new trends of climate change and the emergence of new pests and diseases of soybean. Therefore, in order to address these challenges and develop soybean varieties with desirable traits, there is a need to broaden the genetic base of tropical soybean through the importation of germplasm from other countries.
