Inheritance of antioxidant activity and its association with seed coat color in Cowpea (Vigna unguiculata (l.) walp.)

Analysis of antioxidant activity (AOA) of entries in the 2002 Regional Southernpea Cooperative Trial revealed not only significant differences among entries, but that entries with pigmented (black and red) seed coats were clustered among the highest, cream types were the lowest, while pinkeye and blackeye types were intermediate. Red colored peas were higher in antioxidant activity than black types. These findings provided strong evidence that compounds responsible for pigmentation were involved in AOA. The objectives of the present investigation were to investigate the inheritance of AOA in cowpea and further study the relationship between AOA and seed coat color. Four advanced selections, ARK95-356 (black), ARK98-348 (red), ARK96-918 (cream), and LA92-180 (cream), were crossed in a complete diallel mating design, generating F1, F1', F2, F2', BC1, and BC2 populations. Individual seeds were ground and samples were extracted in methanol and analyzed for AOA using the free radical 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) method. Combining ability tests using Griffing??s Method I Model I indicated presence of highly significant general combining ability (GCA), specific combining ability (SCA), and reciprocal (REC) and maternal (MAT) effects, with pigmented lines exhibiting positive GCA and MAT, while non-pigmented lines exhibited negative GCA and MAT. AOA in the F1 was not significantly different from the maternal parent, with seed coat color also resembling the maternal parent. Segregation for seed coat color was observed in the F2 and F2'. Additive, dominance, and epistatic effects were significant. The broad sense heritability estimate was 0.87. Minimum number of genes responsible for AOA was estimated at about five. Factors governing high AOA appeared to be the same as those responsible for seed coat color, with apparent pleiotropic effects. In conclusion, breeding for high AOA is possible using highly pigmented parental lines

Relationships among antioxidants, phenolics, and specific gravity in potato cultivars, and evaluation of wild potato species for antioxidants, glycoalkaloids, and anti-cancer activity on human prostate and colon cancer cells in vitro.

Understanding the influence of environment and correlation/relationships among traits is necessary in selection for crop quality improvement. Therefore, correlations among antioxidant activity (AOA), total phenolics (TP), phenolic composition, and specific gravity (SPG) in four potato (Solanum tuberosum, L.) cultivars (Atlantic, Red La Soda, Russet Norkotah, and Yukon Gold) grown in nine states (California, Idaho, Michigan, Minnesota, New Jersey, North Carolina, Oregon, Texas, and Wisconsin) for three years, and in 15 advanced selections grown in Texas were investigated. Cultivars within and between locations were significantly different in AOA, TP, and SPG. Significant effects of cultivar, year, location and their interactions on AOA, TP, and SPG were observed. There were significant positive correlations among the four cultivars between AOA and TP, and negative correlations between AOA and SPG, and between TP and SPG. However, correlations between AOA and SPG, and between TP and SPG, in the advanced selections were not significant. Some tuber-bearing wild potato species were higher in AOA and TP than the commercial cultivars; therefore, they could be used as parental material in breeding for high AOA and TP. However, use of wild species that might be higher in total glycoalkaloids (TGA) than cultivars could result in progenies with high TGA if the traits are positively correlated. To elucidate the relationships among AOA, TP and TGA, accessions of Solanum jamesii and S. microdontum from the US Potato Genebank were screened for these traits and their correlations determined. Also, anti-proliferative and cytotoxic effects of 15 S. jamesii tuber extracts (5 and 10 μg/ml) on human prostate (LNCaP) and colon (HT-29) cancer cells was determined in vitro. Alpha-solanine and α-chaconine were found in both species, while tomatine and dehydrotomatine were quantified in some S. microdontum accessions. Both species were higher in all above traits than the Atlantic, Red La Soda, and Yukon Gold cultivars. More than 90% of S. jamesii accessions had TGA levels < 20 mg/100g fresh weight, while only two accessions of S. microdontum, P1 500041 and PI 473171, exhibited TGA < 20 mg/100g. Neither AOA nor TP was significantly correlated with TGA in both species. Also, individual phenolics were not correlated with TGA. Solanum jamesii accessions significantly reduced proliferation of HT-29 (5 and 10μg/ml) and LNCaP (10μg/ml) cells and were not cytotoxic compared to the control (DMSO). Therefore, since AOA and TP were not found to be correlated with TGA, using wild accessions in breeding for increased health promoting compounds would not necessarily increase glycoalkaloids in newly developed potato cultivars

Participatory assessment of potato production constraints and trait preferences in potato cultivar development in Rwanda

Potato (Solanum tuberosum L.) is the major food and cash crop in the highland regions of Rwanda. However, farmers are not integrated into the potato breeding process. The objectives of this research were to identify farmers’ key potato production constraints and establish preferred traits in potato cultivar development in Rwanda. A participatory rural appraisal (PRA) study was conducted through structured survey involving 144 households and 22 focus groups with 258 participants in Musanze, Gicumbi and Nyamagabe districts. The structured survey used a questionnaire administered to farmers to collect information on importance of potatoes and other main crops. While focus groups discussions used matrix scoring of key production constraints and pair-wise ranking of traits. Potato is the most important food and cash crop, followed by maize, beans and wheat. The dominant potato varieties are Kirundo, Cruza, Mabondo and Victoria. The most important potato production constraints are lack of access to credit, lack of high yielding cultivars, insufficient clean seeds and late blight disease. Variety Mabondo is the most tolerant to late blight, followed by Cruza, Kirundo, Kinigi and Rutuku in all the districts. High yield, disease tolerance and high dry matter content are the most important attributes preferred by farmers. Active farmer participation in early breeding stages is critical for a successful potato breeding programme

Population structure analysis and association mapping of seed antioxidant content in USDA cowpea (Vigna unguiculata L. Walp.) core collection using SNPs

Cowpea (Vigna unguiculata L. Walp.) is an important legume, and the antioxidant content in cowpea seeds has been recognized as a health-promoting compound for humans. The objectives of this study were to analyze the population structure of cowpea collections and to identify single nucleotide polymorphism (SNP) markers associated with the seed antioxidant content and seed coat color. A set of 1,047 SNPs were used to analyze 369 cowpea core collection from 47 countries. Results indicated that: (1) there were three clusters in the 369 entries; and the germplasm collected from India, South Africa, and the US showed broader genetic diversity; (2) Scaffold7139_14363 and Scaffold29110_4657 were strongly associated with antioxidant content, and C35063613_1497, Scaffold81493_886, and Scaffold84620_6785 were strongly associated with seed coat color across three models; (3) significant correlations were detected between the seed antioxidant content and black seed color (r = 0.45), between seed antioxidant content and red seed coat color (r = 0.50); and (4) Scaffold42008_191 and C35082838_2258 were associated with both seed antioxidant content and seed coat color. The SNP markers identified could potentially be used in marker-assisted breeding to accelerate genetic improvement of cowpea for higher seed antioxidant content.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author