Linkage drag analysis in three Aegilops speltoides introgressions carrying Sr47 in modern durum and hard red spring wheat germplasm.

KEY MESSAGE: Yield and quality tests of wheat lines derived from RWG35 show they carry little, or no linkage drag and are the preferred source of Sr47 for stem rust resistance. Three durum wheat (Triticum turgidum L. subsp. durum) lines, RWG35, RWG36, and RWG37 carrying slightly different Aegilops speltoides introgressions, but each carrying the Sr47 stem rust resistance gene, were backcrossed to three durum and three hard red spring (HRS) wheat (Triticum aestivum L.) cultivars to produce 18 backcross populations. Each population was backcrossed to the recurrent parent six times and prepared for yield trials to test for linkage drag. Lines carrying the introgression (S-lines) were compared to euploid sibling lines (W-lines) and their parent. Yield trials were conducted from 2018 to 2021 at three locations. Three agronomic and several quality traits were studied. In durum, lines derived from RWG35 had little or no linkage drag. Lines derived from RWG36 and RWG37 still retained linkage drag, most notably involving yield and thousand kernel weight, but also test weight, falling number, kernel hardness index, semolina extract, semolina protein content, semolina brightness, and peak height. In HRS wheat, the results were more complex, though the general result of RWG35 lines having little or no linkage drag and RWG36 and RWG37 lines retaining linkage drag still applied. But there was heterogeneity in the Glenn35S lines, and Linkert lines had problems combining with the Ae. speltoides introgressions. We concluded that introgressions derived from RWG35 either had eliminated linkage drag or any negative effects were minor in nature. We recommend that breeders who wish to incorporate Sr47 into their cultivars should work exclusively with germplasm derived from RWG35.

Cytogenetic and genomic characterization of a novel tall wheatgrass-derived Fhb7 allele integrated into wheat B genome.

KEY MESSAGE: We identified and integrated the novel FHB-resistant Fhb7The2 allele into wheat B genome and made it usable in both common and durum wheat breeding programs without yellow flour linkage drag. A novel tall wheatgrass-derived (Thinopyrum elongatum, genome EE) Fhb7 allele, designated Fhb7The2, was identified and integrated into the wheat B genome through a small 7B-7E translocation (7BS·7BL-7EL) involving the terminal regions of the long arms. Fhb7The2 conditions significant Type II resistance to Fusarium head blight (FHB) in wheat. Integration of Fhb7The2 into the wheat B genome makes this wild species-derived FHB resistance gene usable for breeding in both common and durum wheat. By contrast, other Fhb7 introgression lines involving wheat chromosome 7D can be utilized only in common wheat breeding programs, not in durum wheat. Additionally, we found that Fhb7The2 does not have the linkage drag of the yellow flour pigment gene that is tightly linked to the decaploid Th. ponticum-derived Fhb7 allele Fhb7Thp. This will further improve the utility of Fhb7The2 in wheat breeding. DNA sequence analysis identified 12 single nucleotide polymorphisms (SNPs) in Fhb7The2, Fhb7Thp, and another Th. elongatum-derived Fhb7 allele Fhb7The1, which led to seven amino acid conversions in Fhb7The2, Fhb7Thp, and Fhb7The1, respectively. However, no significant variation was observed in their predicted protein configuration as a glutathione transferase. Diagnostic DNA markers were developed specifically for Fhb7The2. The 7EL segment containing Fhb7The2 in the translocation chromosome 7BS·7BL-7EL exhibited a monogenic inheritance pattern in the wheat genetic background. This will enhance the efficacy of marker-assisted selection for Fhb7The2 introgression, pyramiding, and deployment in wheat germplasm and varieties.

Phenotypic, Phytochemical, and Transcriptomic Analysis of Black Sorghum (Sorghum bicolor L.) Pericarp in Response to Light Quality.

Black sorghum [Sorghum bicolor (L.) Moench] is characterized by the black appearance of the pericarp and production of 3-deoxyanthocyanidins (3-DOA), which are valued for their cytotoxicity to cancer cells and as natural food colorants and antioxidant additives. The black pericarp phenotype is not fully penetrant in all environments, which implicates the light spectrum and/or photoperiod as the critical factor for trait expression. In this study, black- or red-pericarp genotypes were grown under regimes of visible light, visible light supplemented with UVA or supplemented with UVA plus UVB (or dark control). Pericarp 3-DOAs and pericarp pigmentation were maximized in the black genotype exposed to a light regime supplemented with UVB. Changes in gene expression during black pericarp development revealed that ultraviolet light activates genes related to plant defense, reactive oxygen species, and secondary metabolism, suggesting that 3-DOA accumulation is associated with activation of flavonoid biosynthesis and several overlapping defense and stress signaling pathways.

Tannin Analysis in Sorghum Grains.

Sorghum (Sorghum bicolor (L.) Moench) contains a wide variety of phenolic compounds and their levels and types depend on the genotype. Sorghums with a pigmented testa contain condensed tannins, which are concentrated in the pigmented testa. In this chapter, three methods of tannin analysis are described: (1) Chlorox bleach test; (2) modified vanillin-HCl assay; and (3) normal-phase high-performance liquid chromatography (NP-HPLC) with fluorescence detection. The Chlorox bleach test is a rapid and inexpensive method that identifies non-tannin and tannin sorghums. The modified vanillin-HCl assay is a colorimetric assay that provides relative tannin values among sorghum samples. The normal-phase HPLC with fluorescence detection separates and quantifies condensed tannins according to their degree of polymerization and confirms the presence or absence of tannins.

Sorghum Phytochemicals and Their Potential Impact on Human Health.

Sorghum contains a wide array of phytochemicals and their levels are affected by the genotype. Phytochemicals identified in sorghum include phenolic acids, flavonoids, condensed tannins, polycosanols, phytosterols, stilbenes, and phenolamides. Most of these phytochemicals are concentrated in the bran fraction and have been shown to have several potential health benefits, which include antidiabetic, cholesterol-lowering, anti-inflammatory, and anticancer properties. This chapter gives an overview of sorghum genetics relevant to phytochemicals, phytochemicals identified in sorghum grain, and their potential health benefits.

Impact of Novel Sorghum Bran Diets on DSS-Induced Colitis.

We have demonstrated that polyphenol-rich sorghum bran diets alter fecal microbiota; however, little is known regarding their effect on colon inflammation. Our aim was to characterize the effect of sorghum bran diets on intestinal homeostasis during dextran sodium sulfate (DSS)-induced colitis. Male Sprague-Dawley rats (N = 20/diet) were provided diets containing 6% fiber from cellulose, or Black (3-deoxyanthocyanins), Sumac (condensed tannins) or Hi Tannin Black (both) sorghum bran. Colitis was induced (N = 10/diet) with three separate 48-h exposures to 3% DSS, and feces were collected. On Day 82, animals were euthanized and the colon resected. Only discrete mucosal lesions, with no diarrhea or bloody stools, were observed in DSS rats. Only bran diets upregulated proliferation and Tff3, Tgfß and short chain fatty acids (SCFA) transporter expression after a DSS challenge. DSS did not significantly affect fecal SCFA concentrations. Bran diets alone upregulated repair mechanisms and SCFA transporter expression, which suggests these polyphenol-rich sorghum brans may suppress some consequences of colitis.

Influence of Genetic Background on Anthocyanin and Copigment Composition and Behavior during Thermoalkaline Processing of Maize.

Visual color is a primary quality factor for foods purchase; identifying factors that influence in situ color quality of pigmented maize during processing is important. Twenty-four genetically distinct pigmented maize hybrids (red/blue, blue, red, and purple) were used to investigate the effect of pigment and copigment composition on color stability during nixtamalization and tortilla chip processing. The red/blue and blue samples generally contained higher proportions of acylated anthocyanins (mainly cyanidin-3-(6″-malonylglucoside)) than the red and purple color classes. Phenolic amides were the major extractable copigments in all samples (450-764 µg/g), with red samples containing the most putrescines and blue samples containing the most spermidines. Even though samples with higher proportions of acylated anthocyanins retained more pigments during processing, this did not relate to final product color quality. In general, the red/blue samples retained their color quality the best and thus are good candidates for genetic improvement for direct processing into alkalized products.

Enhanced action of apigenin and naringenin combination on estrogen receptor activation in non-malignant colonocytes: implications on sorghum-derived phytoestrogens.

Activation of estrogen receptor-ß (ERß) is an important mechanism for colon cancer prevention. Specific sorghum varieties that contain flavones were shown to activate ER in non-malignant colonocytes at low concentrations. This study aimed to determine positive interactions among estrogenic flavonoids most relevant in sorghum. Apigenin and naringenin were tested separately and in combination for their ability to influence ER-mediated cell growth in non-malignant young adult mouse colonocytes (YAMC). Sorghum extracts high in specific flavanones and flavones were also tested. Apigenin reduced ER-mediated YAMC cell growth comparable to physiological levels of estradiol (E2, 1 nM) at 1 µM; naringenin had similar effect at 10 µM. However, when combined, 0.1 µM apigenin plus 0.05 µM naringenin produced similar effect as 1 nM E2; these concentrations represented 1/10th and 1/200th, respectively, of the active concentrations of apigenin and naringenin, demonstrating a strong enhanced action. A sorghum extract higher in flavones (apigenin and luteolin) (4.8 mg g(-1)) was more effective (5 µg mL(-1)) at activating ER in YAMC than a higher flavanone (naringenin and eriodictyol) (28.1 mg g(-1)) sorghum extract (10 µg mL(-1)). Enhanced actions observed for apigenin and naringenin were adequate to explain the level of effects produced by the high flavone and flavanone sorghum extracts. Strong positive interactions among sorghum flavonoids may enhance their ability to contribute to colon cancer prevention beyond what can be modeled using target compounds in isolation.

Thermal stability of 3-deoxyanthocyanidin pigments.

3-Deoxyanthocyanidins are promising natural colourants due to their unique properties compared to anthocyanins. However, thermal stability of 3-deoxyanthocyanidins is largely unknown. Thermal stability of crude and pure 3-deoxyanthocyanidins was determined at 95 °C/2 h and 121 °C/30 min, at pH 1-7 using HCl, formic or citric acid as acidulants. The colour retention of crude and pure 3-deoxyanthocyanidins (79-89% after 95 °C/2 h and 39-118% after 121 °C/30 min) was high compared to literature reports for anthocyanins under similar treatments. pH significantly affected the thermal stability of 3-deoxyanthocyanidins: Colour retention was better at pH 1-2 (70.2-118%) than at pH 3-7 (39.0-86.8%). Chalcones were identified as the major heat degradation products at pH 3-7. Slow rate of chalcone formation and resistance to C-ring fission were identified as the major contributors to thermal stability of 3-deoxyanthocyanidins. Overall, the heat stability of 3-deoxyanthocyanidins indicates good potential for food use.

Phenolic composition and inhibitory effect against oxidative DNA damage of cooked cowpeas as affected by simulated in vitro gastrointestinal digestion.

Cowpeas contain phenolic compounds with potential health benefits. The effect of simulated gastrointestinal digestion on phenolic composition of cooked cowpeas and the ability of the digests to inhibit radical-induced DNA damage was determined. A red and a cream-coloured cowpea type were used. The phenolic composition of acetone extracts and enzyme digests of cooked cowpeas was determined using UPLC-MS. Compounds such as p-hydroxybenzoic acid, p-coumaric acid, coumaroylaldaric acid and feruloylaldaric acid were present in the acetone extracts of the cooked cowpeas but were not detected in the enzyme digests. Glycosides of quercetin and myricetin decreased upon in vitro gastrointestinal digestion of cooked cowpeas whereas flavan-3-ols were hardly present except catechin glucoside. The enzyme digest of the red cowpea type was about thrice as effective as that of the cream cowpea type in protecting DNA from oxidative damage. The observation that enzyme digests of cooked cowpeas inhibited radical-induced DNA damage suggests that cowpea phenolics retain some radical scavenging activity after gastrointestinal digestion.

Proanthocyanidin profile of cowpea (Vigna unguiculata) reveals catechin-O-glucoside as the dominant compound.

Proanthocyanidin (PA) profile and content can have important nutritional and health implications on plant foods. Six diverse cowpea phenotypes (black, red, green, white, light-brown and golden-brown) were investigated for PA composition using normal-phase HPLC and reversed-phase UPLC-TQD-MS. Catechin and (epi)afzelechin were the major flavan-3-ol units. Unusual composition was observed in all cowpea phenotypes with significant degrees of glycosylation in the monomers and dimers. The PA content of cowpea (dry basis) ranged between 2.2 and 6.3 mg/g. Monomeric flavan-3-ols were the largest group of PA (36-69%) in cowpea, with catechin-7-O-glucoside accounting for most (about 88%) of the monomers. The oligomers with degree of polymerization (DP) 2-4 ranged from 0.41 to 1.3 mg/g (15-20%), whereas DP>10 polymers accounted for only 13.5% of PA. Future studies that highlight the impact of the unusual cowpea PA profile on nutritional and bioactive properties of this important legume are warranted.

Ultra performance liquid chromatography-tandem quadrupole mass spectrometry profiling of anthocyanins and flavonols in cowpea (Vigna unguiculata) of varying genotypes.

The structure of flavonoids in food plants affects bioactivity and important nutritional attributes, like micronutrient bioavailability. This study investigated flavonol and anthocyanin compositions of cowpea (Vigna unguiculata) of varying genotypes. Black, red, green, white, light brown, and golden brown cowpea phenotypes were analyzed for anthocyanins and flavonols using ultra performance liquid chromatography-tandem quadrupole mass spectrometry. Eight anthocyanins and 23 flavonols (15 newly identified in cowpea) were characterized. Mono-, di-, and tri(acyl)glycosides of quercetin were predominant in most phenotypes; myricetin and kaempferol glycosides were present only in specific phenotypes. The red phenotypes had the highest flavonol content (880-1060 µg/g), whereas green and white phenotypes had the lowest (270-350 µg/g). Only black (1676-2094 µg/g) and green (875 µg/g) phenotypes had anthocyanins, predominantly delphinidin and cyanidin 3-O-glucosides. Cowpea phenotype influenced the type and amount of flavonoids accumulated in the seed; this may have implications in selecting varieties for nutrition and health applications.

Flavonoid composition of lemon-yellow sorghum genotypes.

Flavonoid composition of lemon-yellow sorghums grown in two locations in Texas, USA was evaluated and compared with that of white and red sorghums using high performance liquid chromatography (HPLC-PDA). Sorghums from Lubbock were brighter in colour and had minimal weathering compared to those from College Station. Sorghums with red/purple secondary plant colour had the highest levels of 3-deoxyanthocyanidins (8-187µg/g) and their levels were highest in grains from College Station (39-187µg/g). Pericarp colour did not have any effect on 3-deoxyanthocyanidin levels (p>0.05). The tan plant lemon-yellow sorghum Tx2953 had the highest levels of flavones (268-362µg/g). Among the genotypes, lemon-yellow sorghums had the highest levels of flavanones (134-1780µg/g), which are located in the pericarp and their levels were increased in the grains with a bright yellow pericarp and minimal weathering. The high flavanone levels in lemon-yellow sorghums makes this sorghum genotype a good source of those compounds.

Phenolic compounds and antioxidant activity of sorghum grains of varying genotypes.

The effects of plant color, pericarp thickness, pigmented testa, and spreader genes on phenols and antioxidant activity levels of 13 sorghum genotypes were evaluated. Total phenols, condensed tannins, flavan-4-ols, and anthocyanins were measured. Antioxidant activity levels using the 2,2'-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl assays were evaluated. Sorghums with a pigmented testa and spreader genes (B(1)()B(2)()S) had the highest levels of phenols and antioxidant activity. In addition, sorghums with purple/red plants (PQ) and thick pericarp (z) genes had increased levels of phenols and antioxidant activity. Sorghums with a black pericarp had higher levels of flavan-4-ols and anthocyanins than the other varieties. This suggests that genes for plant color, pericarp thickness, presence of a pigmented testa, and spreader genes increase phenols and antioxidant activity levels. This information can be useful in the production of sorghums with increased phenols and antioxidant activity levels.

Processing of sorghum (Sorghum bicolor) and sorghum products alters procyanidin oligomer and polymer distribution and content.

Sorghum procyanidins were characterized and quantified from two brown sorghum varieties and their processed products by normal phase HPLC with fluorescence detection. The DP of the procyanidins was determined by thiolysis. Quantification was done by using purified oligomeric and polymeric cocoa procyanidins as external standards. Sorghum procyanidins were composed mostly of high MW (DP > 10) polymers. Significant differences were observed in levels as well as distribution of the different MW procyanidins between the sorghums. Processing of the sorghum brans into cookies and bread significantly reduced the levels of procyanidins; this effect was more pronounced in the higher MW polymers. Cookies had a higher retention of procyanidins (42-84%) than bread (13-69%). Extrusion of sorghum grain resulted in an increase in the levels of procyanidin oligomers with DP /= 6. This suggests a possible breakdown of the high MW polymers to the lower MW constituents during extrusion. Processing changes not only the content of procyanidins in sorghum products but also the relative ratio of the different molecular weights.