Endosperm Type Research Articles

Nitrogen fertilization levels influence the physicochemical properties of floury rice varieties

AbstractBackground and objectivesThis study was conducted to determine the effect of nitrogen fertilization level during cultivation on physicochemical properties of two floury rice varieties (Shingil and Garumi 2) with different endosperm types under dry‐milling process.FindingsIn both varieties, the protein content was increased in proportion to the level of nitrogen fertilization, while the amylose content exhibited a slight decrease in the highest nitrogen fertilization level. Damaged starch and digestible starch fractions were decreased with increasing nitrogen fertilization for both varieties, maybe due to the reduction in total starch relative to the protein content. Nevertheless, the level of damaged starch increased in Shingil under the highest nitrogen fertilization of 270 kg/ha, suggesting that nitrogen fertilization level can affect the physicochemical characteristics of starch particles during dry milling. The proportion of short amylopectin chains (DP6‐12) decreased with increasing nitrogen fertilization. The difference was more prominent in Shingil than the other variety Garumi 2, indicating that Shingil could experience a greater increase in hardening and a faster retrogradation by increased nitrogen fertilization level than Garumi 2.ConclusionsNitrogen fertilization levels during rice growth affected the starch and protein contents in the endosperm, the chain length of amylopectin, which should, in turn, contribute to the processing properties of floury rice varieties.Significance and noveltyThis study will help develop fertilization strategies for the novel floury rice varieties and consequently provide helpful information to the rice‐processing food industry.

Genetic diversity and heterotic orientation of South Africa maize inbred lines towards tropical and temperate testers

An efficient hybrid breeding program defines and utilizes a few heterotic groups. Objectives of this study were to determine genetic diversity and alignment of South Africa maize inbred lines collection towards tropical and temperate testers. Forty-four maize inbred lines were genotyped with 56,110 single nucleotide polymorphism (SNP) markers. A total of 40 lines were crossed to two tropical and two temperate inbred line testers. Due to seed shortages, testcross hybrids containing 14 and 18 lines were used in 2014/2015 and 2015/2016 seasons, respectively. Genotypes and specific combining ability (SCA) effects of hybrids were significantly different (P < 0.05) for grain yield. There was a weak correlation between molecular genetic distances and both grain yield mean performance and SCA effects of hybrids, indicating that productivity of maize inbred lines could not be reliably determined based on molecular genetic distances. The SCA data classified these maize inbred lines into three heterotic groups with respect to both tropical and temperate testers. The study also indicated high level of diversity among the maize inbred lines, which was shown by both the dendogram and molecular genetic distances. The SNP marker data classified the inbred lines into 11 clusters that could be simplified into three major groups of normal maize endosperm and two groups of quality protein maize endosperm types. However, the SNP data indicated that maize lines were more aligned towards the tropical than temperate inbred testers. This information would be useful for simplifying heterotic classification of the lines with profound implications for breeding progress.

Changes in the physical, chemical, and sensory properties from three native corn landraces from Chiapas using two nixtamalization times

The objective of this study was to investigate the variation in physical, chemical, and sensory properties of tortillas when using two nixtamalization cooking times for three native corn landraces with different kernel hardness levels. When Olotón and Comiteco races are cooked with lime for 60 min, tortillas were softer and rolled better. In contrast, when Tuxpeño was nixtamalized for 30 min tortillas were less prone to breaking. Starch gelatinization is the main factor responsible for textural changes, although retrogradation may also be involved. Structural composition of grains affects thermal and rheological properties and, consequently, the texture of tortillas. Textural properties (tension, rollability, and elasticity) of tortillas are affected by the type of endosperm (hard and soft), whereas kernel hardness correlated only with tortilla tension. Chemical composition correlated well with kernel shape, starch thermal (enthalpy) and rheological properties. Protein affected tortilla elasticity, firmness, and smoothness. Fat and carbohydrate were negatively correlated with nixtamal aroma but protein was positively correlated. Crude fiber correlated negatively with tortilla smoothness, and corn-aroma. Even though the perception of aroma, flavor, smoothness was related to corn landrace, cooking time also exerted an effect. A longer nixtamalization cooking time usually reduces the intensity of tortilla sensory properties like corn and nixtamal aromas.

Development of Extra-Early Provitamin A Quality Protein Maize Inbreds with Resistance/Tolerance to Striga hermonthica and Soil Nitrogen Stress

A hemiparasitic plant, Striga hermonthica (Del.) Benth and soil nitrogen stress are the key constraints to maize (Zea mays L.) productivity in sub-Saharan Africa, where commonly cultivated maize is the normal endosperm type that is deficient in provitamin A, tryptophan and lysine (PVATL). Seventy-six extra-early maize inbreds with provitamin A, tryptophan, and lysine qualities (TZEEIORQ) were developed to address these constraints, and four checks were assessed under Striga, low and high nitrogen conditions at three locations in Nigeria. The inbreds were further genotyped with two beta-carotene hydroxylase 1 (crtRB1) markers, and their seeds were quantified for provitamin A content. Significant (P &lt; 0.01) genetic variations were observed for grain yield and other agronomic attributes of the inbreds under varying environmental conditions. Levels of PVATL for the inbreds ranged from 2.21–10.95 µg g−1, 0.04–0.08%, and 0.19–0.39%, respectively. Beta-carotene marker, crtRB1-3′TE, was polymorphic and grouped the inbreds into two. The marker was effective in identifying inbreds with moderate provitamin A content. Inbreds TZEEIORQ 5, TZEEIORQ 52, and TZEEIORQ 55 exhibited resistance to Striga, tolerance to nitrogen stress with moderate levels of PVATL and could be invaluable sources of favorable alleles for breeding nutritionally improved maize varieties with resistance/tolerance to Striga and soil nitrogen stress.

Effects of corn grain endosperm type and fineness of grind on site of digestion, ruminal digestion kinetics, and flow of nitrogen fractions to the duodenum in lactating dairy cows

Our objective was to evaluate effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, and productive performance of lactating cows. Eight ruminally and duodenally cannulated Holstein cows in mid lactation (130 ± 42 d in milk; mean ± standard deviation) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) and fineness of grind (fine or medium). Rations included alfalfa silage, corn treatments, protein supplement, minerals, and vitamins and were formulated to contain 29% starch, 27% neutral detergent fiber, 18.2% forage neutral detergent fiber, and 18% crude protein. Corn grain treatments supplied 86.2% of dietary starch. Endosperm was 25% vitreous for the floury treatment and 66% vitreous for the vitreous treatment. The floury treatment increased rate of starch degradation by 94% (19.2 vs. 9.9%/h) and decreased rate of starch passage by 38% (16.1 vs. 25.8%/h), increasing apparent ruminal starch digestibility by 117% (53.7 vs. 24.7%). The floury treatment increased total-tract starch digestibility by 8% (92.2 vs. 85.1%) despite 37% lower postruminal starch digestion for the floury treatment compared with vitreous corn (38.4 vs. 60.7% of starch intake). Fine grind size increased apparent ruminal starch digestibility by 52% (47.2 vs. 31.1%) compared with medium grind size by increasing the rate of starch degradation by 105% (19.5 vs. 9.5%/h) with no effect on rate of starch passage. However, total-tract starch digestibility was not affected by fineness of grind because postruminal starch digestibility was 37% greater for medium compared with fine grind size (57.2 vs. 41.9% of starch intake). Endosperm type did not affect flow of nitrogen (N) fractions to the duodenum or microbial N efficiency, whereas fine grind size increased duodenal flow of nonammonia N by increasing duodenal flow of microbial N by 22% compared with medium grind size (438 vs. 359 g/d) but did not affect apparent total-tract N digestibility. No interactions were detected for any measure of starch digestion, ruminal N metabolism, or flow of N fractions to the duodenum. Endosperm type greatly affected ruminal and total-tract starch digestibility independent of the fineness of grind of corn grain with no effects on flow of N fractions.

Effects of corn grain endosperm type and conservation method on site of digestion, ruminal digestion kinetics, and flow of nitrogen fractions to the duodenum in lactating dairy cows

Our objective was to evaluate the relative effects of endosperm type and conservation method of corn grain on ruminal kinetics, site of nutrient digestion, and flow of nitrogen fractions to the duodenum in lactating dairy cows. Seven ruminally and duodenally cannulated Holstein cows (73 ± 39 d in milk; mean ± SD) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used, with main effects of corn grain endosperm type (floury or vitreous) and conserved as dry ground corn (DGC) or high-moisture corn (HMC). Rations were formulated to contain 27.0% starch, 26.6% neutral detergent fiber (NDF), 19.1% forage NDF, and 16.5% crude protein. Corn grain treatments supplied 86.6% of dietary starch, and alfalfa silage was the sole forage. True ruminal starch digestibility was increased by HMC compared with DGC (87.2 vs. 64.3%) and by floury compared with vitreous corn grain (83.7 vs. 67.7%). The increase for HMC compared with DGC was because of an increase in the degradation rate (33.8 vs. 23.1%/h) and a decrease in passage rate of starch (7.6 vs. 15.2%/h). The increase for floury compared with vitreous corn grain was because of an increase in the degradation rate (31.5 vs. 25.4%/h) and a decrease in rate of starch passage from the rumen (7.9 vs. 14.9%/h). Apparent total-tract starch digestibility was increased by HMC compared with DGC and by floury compared with vitreous corn, but the increase for floury corn was greater for the DGC treatment. Dry ground corn compared with HMC tended to increase nonammonia N flow to the duodenum (466 vs. 431 g/d) by increasing flow of nonammonia nonmicrobial N (211 vs. 111 g/d) despite a decrease in microbial N flow (255 vs. 320 g/d). Vitreous corn increased nonammonia nonmicrobial N flow to the duodenum (187 vs. 135 g/d) compared with floury corn, but microbial N flow to the duodenum was not affected by endosperm type. Efficiency of microbial N production was not affected by treatment. Endosperm type and conservation method of corn grain greatly affect digestion kinetics and ruminal digestibility of starch as well as flow of N fractions to the duodenum and should be considered during diet formulation for lactating cows.

Effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, and productive performance of lactating dairy cows

Our objective was to evaluate effects of corn grain endosperm type and fineness of grind on feed intake, feeding behavior, ruminal fermentation, and productive performance of lactating cows. Eight ruminally and duodenally cannulated Holstein cows in mid lactation (130 ± 42 d in milk; mean ± standard deviation) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) and fineness of grind of corn grain (fine or medium). Rations were formulated to contain 29% starch, 27% neutral detergent fiber, 18.2% forage neutral detergent fiber, and 18% crude protein. Corn grain treatments supplied 86.2% of dietary starch. Endosperm was 25% vitreous for floury corn and 66% vitreous for vitreous corn. Fineness of grind did not affect dry matter intake (DMI), but floury corn tended to reduce DMI (23.8 vs. 25.1 kg/d) compared with vitreous corn. Floury corn increased meal frequency more for fine grind size (9.57 vs. 9.41 meals/d) than medium grind size (9.78 vs. 9.75 meals/d). However, there were no effects of treatment on any other measure of feeding behavior. Endosperm type did not affect yields of milk or milk components or milk composition except that vitreous corn tended to decrease milk lactose concentration compared with floury corn. Finely ground corn decreased yields of milk (31.1 vs. 33.1 kg/d), 3.5% fat-corrected milk (33.1 vs. 35.1 kg/d), milk fat (1.22 vs. 1.32 kg/d), milk lactose (1.48 vs. 1.59 kg/d), and solids not fat (2.46 vs. 2.63 kg/d) compared with medium grind size. However, fineness of grind did not affect milk composition. Treatments had no effect on change in body weight or body condition score or efficiency of milk production (kg of 3.5% fat-corrected milk/kg of DMI). Mean ruminal pH was not affected by treatment, but pH variance was decreased by vitreous compared with floury corn. Total volatile fatty acids and propionate concentrations in the rumen were increased by floury compared with vitreous corn but were not affected by fineness of grind. Effects of fineness of grind on yield of milk and milk components were greater than the effects of corn grain vitreousness.

Effects of corn grain endosperm type and conservation method on feed intake, feeding behavior, and productive performance of lactating dairy cows

Our objective was to evaluate the effects of corn grain varying in endosperm type and conserved as high-moisture or dry ground corn on dry matter intake (DMI), feeding behavior, ruminal fermentation, and yields of milk and milk components of cows in early to mid-lactation. Seven ruminally and duodenally cannulated Holstein cows (73 ± 39 d in milk; mean ± SD) were used in a duplicated 4 × 4 Latin square design with 21-d periods. A 2 × 2 factorial arrangement of treatments was used with main effects of corn grain endosperm type (floury or vitreous) conserved as high-moisture corn (HMC) or dry ground corn (DGC). Rations were formulated to contain 27.0% starch, 26.6% neutral detergent fiber (NDF), 19.1% forage NDF, and 16.5% crude protein. Corn grain treatments supplied 86.6% of dietary starch and contained alfalfa silage as the sole forage. Dry matter intake was increased 1.3 kg/d by DGC compared with HMC. The increase in DMI by DGC was related to a shorter intermeal interval (104.4 vs. 118.2 min/d), and meal size was not affected by treatment. Dry ground corn decreased rumination bout length and number of chews per bout compared with HMC. No differences were detected between endosperm treatments for DMI, yields of milk, 3.5% fat-corrected milk (FCM), milk fat, protein, lactose, or solids-not-fat (SNF). Mean yield of 3.5% FCM across treatments was 47.5 kg/d. However, a tendency for an interaction was observed for feed efficiency; floury endosperm increased efficiency 0.05 kg 3.5% FCM per kg of DMI for DGC but decreased it by 0.14 kg 3.5% FCM per kg of DMI for HMC relative to vitreous endosperm. Vitreous compared with floury corn tended to increase true protein concentration in milk when conserved as DGC (2.68% vs. 2.62%) but not as HMC. Concentration of SNF was increased by DGC compared with HMC (8.45 vs. 8.37%) due, in part, to the effect of treatment on milk protein concentration. Body weight was not affected by treatment, but vitreous endosperm tended to increase loss of body condition compared with floury endosperm. Corn endosperm type and conservation method had little effect on productive performance of high-producing cows.

Endosperm of Angiosperms and Genomic Imprinting.

Modern ideas about the role of epigenetic systems in the regulation of gene expression allow us to understand the mechanisms of vital activities in plants, such as genomic imprinting. It is important that genomic imprinting is known first and foremost for the endosperm, which not only provides an embryo with necessary nutrients, but also plays a special biological role in the formation of seeds and fruits. Available data on genomic imprinting in the endosperm have been obtained only for the triploid endosperm in model plants, which develops after double fertilization in a Polygonum-type embryo sac, the most common type among angiosperms. Here we provide a brief overview of a wide diversity of embryo sacs and endosperm types and ploidy levels, as well as their distribution in the angiosperm families, positioned according to the Angiosperm Phylogeny Group IV (APG IV) phylogenetic classification. Addition of the new, non-model taxa to study gene imprinting in seed development will extend our knowledge about the epigenetic mechanisms underlying angiosperm fertility.

Influence of variety endosperm type and seed moisture content on threshability and mechanical damage of sorghum seeds

Abstract. Sorghum is an important cereal crop and it is native in African tropical areas. It is a globally cultivated crop and the fifth most important cereal after maize, rice, wheat and barley. The objective of this study was to determine the effects of endosperm type, seed moisture content and threshing methods on percentage threshability and mechanical damage of sorghum seeds. Two varieties of sorghum (Kari-mtama 1 and Seredo) were grown in two diverse locations, Kiboko and Katumani. Variety Kari-mtama1 has hard (vitreous) endosperm while the other variety Seredo has soft (non-vitreous) endosperm. After harvesting, sorghum panicles were dried in the sun and oven. The panicles were threshed separately for each drying method at two moisture levels, namely 18-20% and 13-14%. The three threshing methods used included beating with wooden stick in tied sack, using wooden mortar and pestle as well as using threshing machine. The results showed that the vitreous endosperm variety had significantly high percentage threshability and significantly low mechanical damage than non-vitreous endosperm variety under both drying methods. There was a significant (p≤0.05) increase in threshability and decrease in mechanical damage when the seeds were threshed at 13-14% moisture content compared to 18-20%. For better seed quality, threshing machine is the best method to be used to avoid mechanical damage and seed quality deterioration. Drying methods used to dry seed panicles before threshing had no effects on threshability and mechanical damage. This implies that sorghum panicles can be dried either in the sun or oven without affecting threshability and mechanical damage at the two moisture levels and by using the three threshing methods.

Relationship between the corneous and floury endosperm content and the popped sorghum quality

Popcorn is a healthy snack suggested by nutritionists. However, some countries in Europe, Asia, and South America have evaluated the use of sorghum as a popped cereal. Therefore, this study aims to evaluate the content of corneous and floury endosperm of sorghum and its influence in the popped sorghum quality. Five red varieties and three white varieties were evaluated. The physical and microstructural characteristics of the raw varieties were evaluated. The correlation matrix showed that physical properties such as the pericarp thickness, the hectoliter weight, and the type of endosperm are crucial to obtain popped sorghum. A high percentage of corneous endosperm and the size distribution of starch granules in the floury endosperm determine the popping ability of sorghum. The analysis of the principal components showed that the Paloma variety was the most suitable to obtain popped sorghum.

Improvement of grain sorghum nutritive properties using modern genetic and biotechnological methods

The paper presents a review of the studies on the use of genetic engineering and genome editing tools for improving nutritional properties of sorghum grain. As a result of experiments performed over the past 5-7 years by several research groups, the created transgenic lines carry genetic constructs for RNA silencing of different kafirin sub-classes (prolamins of sorghum grain). The CRISPR/Cas9 genome editing experiments have yielded mutants with deletions and insertions in the signal sequence of the gene encoding the 22 kDa α-kafirin in sorghum. These lines and mutants were characterized by improved in vitro digestibility of grain proteins, altered ultrastructure of protein bodies and an increased content of lysine. RNA silencing of α-kafirin increased the digestibility of proteins of both raw and cooked flour, while silencing of γ-kafirin led to improved digestibility of proteins of only raw flour. The lines with α-kafirin silencing have kernels with the floury endosperm type that discourages their direct commercial use because of fragility and reduced tolerance to fungal contamination; however, these lines can be used as donors of high digestibility trait when crossed with sorghum lines adapted to local conditions to improve their nutritional value. Kernels of the lines with γ-kafirin silencing may have different endosperm types: floury, vitreous, or a modified type with vitreous endosperm interspersed in the floury endosperm. This fact indicates the possibility of producing agronomically important sorghum lines with high kafirin digestibility and hard endosperm. The increased lysine level in kernels of sorghum lines with the suppressed synthesis of kafirins may be caused by rebalancing of protein synthesis in endosperm of developing kernels due to the synthesis of other proteins, including those with a higher content of essential amino acids. Alongside with improving the digestibility of kafirins, the genetic engineering approach allowed the creation of sorghum lines with a high content of provitamin A in grain and its increased stability during long-term storage. The results of these works show that it is promising to use RNA-interference and genome editing for creating sorghum lines with improved nutritional value of grain.

Physicochemical properties of vitreous and floury endosperm flours in maize.

Three maize cultivars with different endosperm types (flint, semiflint, and dent maize cultivars) were studied to characterize vitreous endosperm flour properties compared with those of floury endosperm flour from the same maize kernels. Vitreous endosperm flour had higher amylose and protein contents, and lower starch content, higher percentage of large starch granule, bigger mean diameter of starch granule, higher iodine capacity, higher trough viscosity and final viscosity and setback, lower swelling power, lower peak viscosity and breakdown, and higher peak time and pasting temperature than the counterpart floury endosperm flour. X‐ray diffraction analysis indicated typical A‐pattern for starches of vitreous and floury endosperm flours. Floury endosperm flour showed the presence of greater crystallinity and higher enthalpy change (∆Hgel) than vitreous endosperm flour for three cultivars. Retrogradation enthalpy (∆Hret) and retrogradation percentage (R) of vitreous and floury endosperm flours ranged from 6.23 to 7.92 J/g and 52.72% to 73.62%, and from 5.46 to 6.45 J/g and 45.70% to 56.58%, respectively. In conclusion, vitreous and floury endosperm flours had significantly different physicochemical properties. Results of this study provide a foundation for better and valid utilization of different endosperm section during grain processing.

Tamales texture properties as a function of corn endosperm type

Tamales are a kind of steam cooked small cakes usually made with nixtamalized cornmeal, pork lard, salt and wrapped in corn cob bracts. Nowadays, tamales could be considered as an essential dish for cuisines of almost all Latin America and even the Southern United States. Tamales' flavour is simple and quite neutral as they can be filled with different sauces and fillings give them their typical organoleptic richness. Additionally, the firm, spongy, slightly resilient texture is typical and distinctive of this food. Moreover, texture is important because it is a quality which allows the dough to adequately hold the fillings. In this study, changes in the texture properties of tamales as a function of corn endosperm (hard, intermediate and soft endosperm) were evaluated. Tamales with the highest content of Flint (hard) cornmeal had the highest adhesiveness and the lowest gumminess. Conversely, tamales richer in Floury (soft) cornmeal had the highest gumminess and the lowest adhesiveness. Binary blends produce values close to the average, just as the Dent (intermediate) cornmeal yields intermediate effects. There was no synergistic or antagonistic effect caused by the mixture of the races cornmeal. Variations in the tamales texture properties are influenced by the kernel hardness, the cornmeal particle size dispersion and its amylose content.

Moisture and Rupture Models for Corn (Zea mays) Seeds of Different Endosperm Types

Abstract. Mechanization of postharvest handling and conditioning inflicts damage on the physical, physiological, and sanitary qualities of corn (Zea mays) seeds, resulting in significant economic loss. The mechanical damage is related to the compression strength and strain, and therefore to the moisture content (MC) and endosperm type. This study was conducted from 2012 to 2014 at the Montecillo and Chapingo agricultural institutes in Mexico, where physical properties such as volumetric weight; apparent density; rupture compression strength, strain, and energy; and endosperm type were evaluated for five corn seed cultivars (floury, semi-floury, floury-flint, semi-flint, and flint) at seven MC levels (8%, 12%, 16%, 20%, 24%, 28%, and 32% w.b.). The aim of this study was to develop moisture-strength, moisture-strain, and moisture-energy regression models for postharvest handling of corn to prevent quality loss due to mechanization. For three model groups, the relationship (1) between MC and rupture strain was linear and directly proportional for the five studied cultivars; (2) between MC and rupture strength was linear and directly proportional for the floury cultivar, inverse for the semi-flint and flint cultivars, and quadratic for the semi-floury and floury-flint cultivars; and (3) between MC and rupture energy was linear and directly proportional for the floury cultivar and quadratic for the semi-floury, floury-flint, semi-flint, and flint cultivars. The models obtained in this study might be used as a reference for better handling of corn seeds, as none of the five studied varieties had a uniformly superior rupture strength, strain, or energy at the studied MC levels. Floury endosperm types might be handled at high MC and flint endosperm types might be handled at low MC to avoid mechanical damage produced by static loads; both types of endosperm support greater energy loads, e.g., impact, at higher MC. Keywords: Compression, Corn quality, Flint endosperm, Floury endosperm, Moisture, Zea mays.

Pericarp thickness of Korean maize landraces

AbstractThin pericarp is one of crucial selection criteria for high-tender waxy corn hybrid development. A pericarp thickness of 2414 maize landrace accessions including 87 public waxy inbred lines was investigated to select accessions with thin pericarp and to broaden genetic diversity among waxy corn cultivars. Observed pericarp thickness of the 2414 accessions ranged from 16.0 ± 1.56 to 139.2 ± 39.55 µm with the average of 47.7 ± 13.15 µm. More than half of the accessions were below the suggested thickness of &lt;50 µm for high-tender waxy corn hybrid development. Large sample size resulted in significant differences among endosperm types and among collection provinces. This, however, may not translate into considerable difference in tenderness since most averages of different types and collection provinces were &lt;50 µm. Positive correlation (r= 0.55) between the average and standard deviation of pericarp thickness implied that more samples are needed to achieve same level of precision when it comes to selection for thick pericarp than that for thin pericarp. Top 10% thin-pericarped waxy landrace accessions were intercrossed to form a new waxy corn population from this result.

Particle size and endosperm type of dry corn grain altered duodenal flow of B vitamins in lactating dairy cows

The objective of the experiment was to determine if factors such as endosperm type (floury vs. vitreous) and particle size (fine vs. medium) of dry corn grain, known to affect starch digestibility in the rumen, modify apparent ruminal synthesis and duodenal flow of B vitamins in lactating dairy cows. Eight lactating multiparous Holstein cows equipped with rumen and duodenal cannulas were assigned randomly to a treatment sequence according to a 2 × 2 factorial arrangement in duplicate 4 × 4 Latin square design experiment. Duration of each experimental period was 21 d. When expressed per unit of dry matter intake (DMI), floury treatments increased duodenal flow and apparent ruminal synthesis of niacin and folates but tended to increase apparent degradation of thiamin in the rumen. Duodenal flow of thiamin, riboflavin, niacin, folates, and vitamin B12, expressed per unit of DMI, decreased with an increase in particle size. Similarly, apparent degradation of thiamin and riboflavin was greater and apparent synthesis of niacin, folates, and vitamin B12 was reduced when cows were fed coarser dry corn grain particles. Neither endosperm type nor particle size had an effect on duodenal flow and apparent ruminal synthesis of vitamin B6. Apparent ruminal syntheses, expressed per unit of DMI, of all studied B vitamins but thiamin were negatively correlated with apparent ruminal digestibility of neutral detergent fiber. Duodenal flow of microbial N was positively correlated with apparent ruminal synthesis of riboflavin, niacin, vitamin B6, and folates. Under the conditions of the present experiment, except for thiamin, the effects of factors increasing starch digestibility of dry corn grain in the rumen on the amounts of B vitamins available for absorption by the dairy cow seem to be mediated through differences on ruminal digestibility of neutral detergent fiber and, to a lesser extent, on duodenal microbial N flow.

Digestibility of Ensiled Maize Hybrids Differing by Maturity and Endosperm Type

Abstract Selected maize hybrids were analyzed according to the in vivo digestibility of the silage. Eight tested hybrids were grown, harvested, and ensiled under identical conditions. The effect of earliness (early maturity group FAO 230–260 vs moderately early maturity group FAO 290–340) significantly (P &lt; 0.05) affected the chemical composition, fermentation quality, and digestibility of neutral and acid detergent fibre. Type of kernel endosperm (dent vs flint) differed by digestibility of nutrients. Digestibility of dry matter, organic matter, and neutral detergent fibre was the highest for silage of the dent hybrid FAO 250 (73.7, 75.7, and 67.6%, respectively) and these digestibility values were significantly (P &lt; 0.05) lower for silage of the dent hybrid FAO 320 (61.1, 63.4, and 51.4%, respectively). It was concluded that the digestibility differs mainly in dent-type hybrids. All correlation coefficients between the digestibility values were significantly (P &lt; 0.05) high.

Character evolution and missing (morphological) data across Asteridae.

Our current understanding of flowering plant phylogeny provides an excellent framework for exploring various aspects of character evolution through comparative analyses. However, attempts to synthesize this phylogenetic framework with extensive morphological data sets have been surprisingly rare. Here, we explore character evolution in Asteridae (asterids), a major angiosperm clade, using an extensive morphological data set and a well-resolved phylogeny. We scored 15 phenotypic characters (spanning chemistry, vegetative anatomy, and floral, fruit, and seed features) across 248 species for ancestral state reconstruction using a phylogenetic framework based on 73 plastid genes and the same 248 species. Iridoid production, unitegmic ovules, and cellular endosperm were all reconstructed as synapomorphic for Asteridae. Sympetaly, long associated with asterids, shows complex patterns of evolution, suggesting it arose several times independently within the clade. Stamens equal in number to the petals is likely a synapomorphy for Gentianidae, a major asterid subclade. Members of Lamianae, a major gentianid subclade, are potentially diagnosed by adnate stamens, unilacunar nodes, and simple perforation plates. The analyses presented here provide a greatly improved understanding of character evolution across Asteridae, highlighting multiple characters potentially synapomorphic for major clades. However, several important parts of the asterid tree are poorly known for several key phenotypic features (e.g., degree of petal fusion, integument number, nucellus type, endosperm type, iridoid production). Further morphological, anatomical, developmental, and chemical investigations of these poorly known asterids are critical for a more detailed understanding of early asterid evolution.

Incidence and developmental timing of endosperm failure in post-zygotic isolation between wild tomato lineages.

Defective hybrid seed development in angiosperms might mediate the rapid establishment of intrinsic post-zygotic isolation between closely related species. Extensive crosses within and among three lineages of wild tomatoes (Solanum section Lycopersicon) were performed to address the incidence, developmental timing and histological manifestations of hybrid seed failure. These lineages encompass different, yet fairly recent, divergence times and both allopatric and partially sympatric pairs. Mature seeds were scored visually 2 months after hand pollinations, and viable-looking seeds were assessed for germination success. Using histological sections from early-developing seeds from a sub-set of crosses, the growth of three major seed compartments (endosperm, embryo and seed coat) was measured at critical developmental stages up to 21 d after pollination, with a focus on the timing and histological manifestations of endosperm misdevelopment in abortive hybrid seeds. For two of three interspecific combinations including the most closely related pair that was also studied histologically, almost all mature seeds appeared 'flat' and proved inviable; histological analyses revealed impaired endosperm proliferation at early globular embryo stages, concomitant with embryo arrest and seed abortion in both cross directions. The third interspecific combination yielded a mixture of flat, inviable and plump, viable seeds; many of the latter germinated and exhibited near-normal juvenile phenotypes or, in some instances, hybrid necrosis and impaired growth. The overall results suggest that near-complete hybrid seed failure can evolve fairly rapidly and without apparent divergence in reproductive phenology/biology. While the evidence accrued here is largely circumstantial, early-acting disruptions of normal endosperm development are most probably the common cause of seed failure regardless of the type of endosperm (nuclear or cellular).