Victor Njiti

Definition of Soybean Genomic Regions That Control Seed Phytoestrogen Amounts

Soybean seeds contain large amounts of isoflavones or phytoestrogens such as genistein, daidzein, and glycitein that display biological effects when ingested by humans and animals. In seeds, the total amount, and amount of each type, of isoflavone varies by 5 fold between cultivars and locations. Isoflavone content and quality are one key to the biological effects of soy foods, dietary supplements, and nutraceuticals. Previously we had identified 6 loci (QTL) controlling isoflavone content using 150 DNA markers. This study aimed to identify and delimit loci underlying heritable variation in isoflavone content with additional DNA markers. We used a recombinant inbred line (RIL) population (n=100) derived from the cross of “Essex” by “Forrest,” two cultivars that contrast for isoflavone content. Seed isoflavone content of each RIL was determined by HPLC and compared against 240 polymorphic microsatellite markers by one-way analysis of variance. Two QTL that underlie seed isoflavone content were newly discovered. The additional markers confirmed and refined the positions of the six QTL already reported. The first new region anchored by the marker BARC_Satt063 was significantly associated with genistein (P=0.009, R2=29.5%) and daidzein (P=0.007 , R2=17.0%). The region is located on linkage group B2 and derived the beneficial allele from Essex. The second new region defined by the marker BARC_Satt129 was significantly associated with total glycitein (P=0.0005 , R2=32.0%). The region is located on linkage group D1a+Q and also derived the beneficial allele from Essex. Jointly the eight loci can explain the heritable variation in isoflavone content. The loci may be used to stabilize seed isoflavone content by selection and to isolate the underlying genes.

Quantitative Trait Loci Associated with Foliar Trigonelline Accumulation in Glycine Max L

The objective of this study was to utilize a Glycine max RIL population to (1) evaluate foliar trigonelline (TRG) content in field-grown soybean, (2) determine the heritability of TRG accumulation, and (3) identify DNA markers linked to quantitative trait loci (QTLs) conditioning variation in TRG accumulation. Frequency distributions of 70 recombinant inbred lines showed statistically no significant departure from normality (P > .05) for TRG accumulation measured at pod development stage (R4). Six different molecular linkage groups (LGs) (B2, C2, D2, G, J, and K) were identified to be linked to QTLs for foliar TRG accumulation. Two unique microsatellite markers (SSR) on two different linkage groups identified QTL significantly associated with foliar TRG accumulation: a region on LG J (Satt285) (P = .0019, R2 = 15.9%) and a second region on LG C2 (Satt079) (P = .0029, R2 = 13.4%).

Wx intron variations support an allohexaploid origin of the sweetpotato [Ipomoea batatas (L.) Lam]

To clarify the polyploid origin of the sweetpotato, we analyzed retentions of three distinctive types of Waxy intron 2 (Wx-In2) variants among 27 sweetpotato lines and 24 selected relatives and their phylogenetic relationships with Wx-In2 from 11 closest relatives. The three types of Wx-In2 effectively distinguish three diploid constituent genomes of very close homeology in the sweetpotato: Type I is characteristic of some loci in Genome I and III, and Types II and III are specific to loci in Genome II and III. The Type I Wx-In2 variation was found to be retained in 19 sweetpotato lines, Ipomoea littoralis Blume (4×), I. tabascana (4×), and I. tenuissima (2×); Type II to be retained in all 27 sweetpotato lines, I. littoralis Blume, and two I. trifida accessions; Type III to be retained in 13 sweetpotato lines, I. tenuissima, and four distantly related species. Because of the nature of independent random divergence of orthologous intronic sequences, these highly selective retentions of genome-specific or characteristic sweetpotato Wx-In2 variations among four diploid or tetraploid sweetpotato relatives are consistent only with separate lineages of diploid genomes of the sweetpotato. Such an allohexaploid origin of the sweetpotato probably occurred via hybridization between I.tenuissima and I.littoralis Blume, derived earlier from I. trifida and an unidentified species sibling to I. tenuissima. However, neither the involvement of I. tabascana nor a multiple origin of the sweetpotato can be ruled out. The inference is supported by maximal likelihood relationships between the three types of Wx-In2 from the sweetpotato and Wx-In2 from its 11 closest relatives.

Quantitative Trait Loci (QTL) that Underlie SCN Resistance in Soybean (Glycine max (L.) Merr.) PI438489B by 'Hamilton' Re- combinant Inbred Line (RIL) Population

1 Plant Genomics & Biotechnology Lab, Department of Biological Sciences, Fayetteville State University, Fayetteville, NC, USA; 2 Department of Plant, Soil, and Agricultural Systems, Southern Illinois University, Carbondale, IL, USA; 3 Soybean Genomics and Improvement Lab, 10300 Baltimore Ave, Bldg. 006, Rm. 201, Beltsville, MD 20705; 4 Unite de Recherche En Genomique Vegetale, INRA, Ivry, France; 5 USDA-ARS Midsouth Area, Jackson, TN, USA; 6 Department of Agriculture, Alcorn State University, Alcorn State, MS, USA; 7 Plant Pathology Department and Agronomy Department, Iowa State University, Ames, IA 50011-1010.

Value-added probiotic development by high-solid fermentation of sweet potato with Saccharomyces boulardii

Abstract Controlled fermentation of Sweet potato (Ipomoea batatas) var. Beauregard by yeast, Saccharomyces boulardii (MAY 796) to enhance the nutritional value of sweet potato was investigated. An average 8.00 × 1010 Colony Forming Units (CFU)/g of viable cells were obtained over 5‐day high‐solid fermentation. Yeast cell viability did not change significantly over time at 4°C whereas the number of viable yeast cells reduced significantly at room temperature (25°C), which was approximately 40% in 12 months. Overall, the controlled fermentation of sweet potato by MAY 796 enhanced protein, crude fiber, neutral detergent fiber, acid detergent fiber, amino acid, and fatty acid levels. Development of value‐added sweet potato has a great potential in animal feed and human nutrition. S. boulardii‐ fermented sweet potato has great potential as probiotic‐enriched animal feed and/or functional food for human nutrition.

Fermentation Optimization of Macro-Fungus Pleurotus Sajor-Caju on Soymeal

An investigation was undertaken to evaluate the impact of edible mushroom Pleurotus sajor-caju fermentation on the nutritional profile of soymeal under high solid submerged fermentation. Eight day fermentation resulted in changes in the nutritional profile of soymeal. A statistically significant enhancement in fermented sample was seen for crude protein, crude fiber and total amino acid. Except for hydroxyproline and hydroxylysine all amino acids showed significant increase in fermented samples. Specifically, amino acids such as glutamic acid and lysine which are important in animal feed showed significant increase in fermented samples. The overall increase of amino acids ranged from 10% to 200%. Response Surface Methodology (RSM) is an effective tool to optimize submerged fermentation of macro-fungi like Pleurotus. The results of the current study can serve as a basis of optimization of other macro-fugal submerged fermentation.