Submitted to: Legume Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2019
Publication Date: 3/24/2020
Citation: Morris, J.B., Tonnis, B.D., Wang, M.L. 2020. Protein content and seed trait analysis in a subset of the USDA, ARS, PGRCU cowpea [Vigna unguiculata (L.) Walp.] core collection. Legume Research. Available: https://arccjournals.com/uploads/Final-article-attachment-with-doi-LR-529.pdf.
Interpretive Summary: Protein is a very important biochemical for health enhancing uses in humans and the fact that limited information is available for protein content and seed trait variation among samples in a cowpea core collection at the USDA, ARS, Plant Genetic Resources Conservation Unit for use by scientists and breeders. This study shows a wide variation for protein content and several seed traits. The Indian sample (PI 354729) produced the highest protein content and will be useful as breeding material for the development of new varieties.
Technical Abstract: Cowpea (Vigna unguiculata (L.) Walp is consumed by humans and animals as a vegetable and feed, respectively, throughout the world and knowledge is limited regarding the variability and correlations for protein and seed traits within a cowpea core collection at the United States Department of Agriculture (USDA), Agricultural Research Service (ARS), Plant Genetic Resources Conservation Unit’s (PGRCU) germplasm collection. The cowpea core collection representing 111 accessions were analyzed using an analysis of variance on the data, and means were separated using Tukey’s multiple comparison procedure. Correlations between protein content, 100 seed weight, and morphological seed traits were determined using Pearson correlation coefficients. Protein content ranged from 17.60 to 25.71% for all cowpea accessions. The accession, PI 354729 originating from India with small seeds (100 seed weight of 6.15 g), wrinkled white seeds consisting of a speckled to holstein pattern produced a significantly higher protein content of 25.527% than all other cowpea accessions. Eight Indian cowpea accessions produced significantly high protein content averaging 24.423%. These accessions produced variable seed coat colors ranging from mixed to white and seed pattern colors ranged from mixed, variable, brown or black. One hundred seed weights (g) ranged from 7.08 to 15.57 g, and seed textures were primarily smooth. However, PI 527259 from Zimbabwe produced a significantly high mean protein content of 24.664%, medium size seeds (100 seed weight = 10.74 g), mixed seed coat and pattern colors, variable seed pattern, and smooth texture as well. Protein content was significantly correlated with seed pattern (r2 = 0.274***) and seed texture (r2 = 0.346***), however protein content showed a significant negative correlation (r2 = -0.333***) with 100 seed weight. Protein content was also significantly correlated with seed coat color (r2 = 0.136*). One hundred seed weight showed significantly negative correlations with seed pattern (r2 = -0.191**) and seed texture (r2 = -0.265***). Seed coat color showed a significant negative correlation with seed pattern (r2 = -0.14), and seed pattern significantly correlated with seed texture (r2 = 0.197**). Based on these results, potential cowpea cultivars could be developed with improved protein content and morphological seed traits.