Genotypic variation in Fe concentration of barley grain

Abstract

Iron deficiency in humans is the most prevalent micronutrient deficiency worldwide. To screen for high Fe cultivar, genotypic variation in Fe concentration of barley grain was investigated in two collections of barley: 274 standard varieties selected at the Barley Germplasm Center of the Research Institute for Bioresources, Okayama University (SV) and 135 varieties from the Barley Core Collection of Americas (BCCAM). The Fe concentration of barley grain showed large variation, ranging from 24.6 to 63.3 mg kg^?1 in SV, from 21.0 to 83.0 mg kg^?1 in BCCAM barleys. The Fe concentration was not affected by the key characters of barley varieties, kernel row types, and hulled or hull-less. The Fe concentration was also not related to the place of origin of the barley variety. About 90% of total Fe was localized in the grain without hull. These results provide fundamental data for breeding Fe-rich cultivars and for studying the mechanisms involved in genotypic variation in Fe concentration.     

Combining pre-transplanting phosphorus application and green manure incorporation: a trial for reducing fertilizer input

Pre-transplanting phosphorus application is a fertilization method that can reduce phosphorus (P) fertilization of the field and increase P use efficiency. We investigated whether P use efficiency can be increased further by combining pre-transplanting phosphorus application and the green manure practice, using cabbage as a test plant in a field experiment performed from 2006 to 2008. The pre-transplanting phosphorus application successfully reduced P fertilization of the field to half without any yield losses in 2006 and 2008. However, growth and yield could not be maintained with the pre-transplanting phosphorus application when P fertilization was halved in 2007. Differences among seasons and discrepancies in the results compared to previous studies may have arisen from the differences in the field management and the nursery soil used. No benefits of green manure in terms of the subsequent cabbage yield were detected. Consequently, there was no positive effect of the combination of pre-transplanting phosphorus application and incorporation of green manure. Studies with mycorrhizal plants as test plants may be necessary to verify the mechanism of enhanced P supply by the incorporation of green manure, and to examine any potential benefit of combining green manure and pre-transplanting phosphorus application practices.     

Protozoan predation of Escherichia coli in hydroponic media of leafy vegetables

Multiple outbreaks of food poisoning associated with fresh vegetable consumptions have occurred in many countries. Numerous reports have described human pathogenic bacteria, such as Escherichia coli O157:H7 and Salmonella spp., that can internalize into fresh vegetables via root or leaf surfaces. While attempting to obtain the threshold concentration of internalization of E. coli inoculated into hydroponic medium during vegetable cultivation, we observed a rapid decrease in E. coli numbers. In the present study, we determined that the rapid decline in E. coli was not due to a physiological change into a viable but non-culturable (VNC) state. The population crash was instead caused by true bacterial death, as the rapid descent was also confirmed by micro-colony fluorescence in situ hybridization, a culture-independent method that can detect VNC cells. We next monitored the number of E. coli inoculated into intact or filter-sterilized hydroponic medium after cultivation of various types of plants. We found that the number of E. coli in intact hydroponic medium decreased markedly, whereas the level in filter-sterilized hydroponic medium was completely unchanged. This result suggests that biotic factors were present that could be eliminated by filtering. Robust predation of E. coli by protozoa (ciliates and flagellates) was observed using fluorescently labeled bacteria incorporated into the hydroponic medium. Finally, morphological identification of flagellates by scanning electron microscopy revealed the presence of a species of Stramenopiles. These findings suggest the importance of protozoa as bacterial feeders in hydroponic systems and hence the use of these organisms as potential control agents of human pathogenic bacteria.     

QTLs in barley controlling seedling elongation of deep-sown seeds

In drought areas, in which topsoil moisture is low, barley seeds are generally sown in the subsoil (deep-seeding). In order for the shoots of germinating seeds to emerge from the deep soil cover, the coleoptile and the first internode of the seedlings must elongate as an adaptive response to deep-seeding. Here, we have mapped quantitative trait loci (QTLs) for these adaptive characteristics. Elongation of the coleoptile and first internode was investigated using seeds sown under two soil cover conditions: at a depth of 9 cm beneath a soil mixture; and, at a depth of 12 cm beneath vermiculite. We identified multiple alleles for increased coleoptile and first internode elongation using a doubled haploid population of 150 lines generated from a cross between the barley cultivars Harrington and TR306. Composite interval mapping analyses of the data revealed two moderate and eleven small effect QTLs, with at least one QTL on each chromosome. The QTLs on chromosomes 5H and 7H had moderate effects on coleoptile elongation (18.5–27.6% of PVE: phenotypic variance explained; 2.6–3.2 mm of Add: additive effect) and first internode elongation (PVE: 16.6–19.6%; Add: 3.1–3.2 mm). The small effect QTLs showed PVEs of less than 15% and an Add range of 1.2–3.2 mm for both characters. A marker assisted selection approach, using markers linked to the QTLs for seedling elongation at deep-seeding, may eventually enable development of drought tolerant barley hybrids.     

Selective staining and visualization of hyphal sheath of a white-rot fungus <Emphasis Type="Italic">Phanerochaete crassa</Emphasis> WD1694 with phloxine B

The hyphal sheath is a morphological feature of many kinds of fungi. Although the fine structures of the sheath have been studied in detail by a number of electron microscopy techniques, the function and physiology of the hyphal sheath are not yet clarified. One reason for this is that the hyphal sheath is a colorless, mucilaginous, and delicate material so that it is not easily identified. We developed a simple method to visualize and identify the hyphal sheath of the white-rot fungus Phanerochaete crassa WD1694. The small mycelial pellets in shaken liquid cultures of P. crassa WD1694 were stained directly with phloxine B. Both the hyphae and the hyphal sheath that filled the gaps between each of the hyphae were visualized and observed by light microscopy. The stained hyphae were further studied by transmission electron microscopy, atomic force microscopy, and fl uorescence microscopy. Based on these observations, we confirmed that the staining of the hyphae was also due to the presence of the hyphal sheath that closely covered the fungal cell wall. These results clearly showed that the hyphal sheath was selectively stained with phloxine B and could be observed and identified by conventional light microscopy. Part of this report was presented at the 50th Lignin Symposium, Nagoya, October 2005     

Genetic and genomic analyses for predicted methane‐related traits in Japanese Black steers

The objectives of this study were to estimate genetic parameters and to perform a genome‐wide association study (GWAS) for predicted methane‐related traits in Japanese Black steers. The methane production and yield traits were predicted using on‐farm measurable traits, such as dry matter intake and average daily gain. A total of 4,578 Japanese Black steers, which were progenies of 362 sires genotyped with imputed 551,995 single nucleotide polymorphisms (SNPs), had phenotypes of predicted methane‐related traits during the total fattening period (52 weeks). For the estimation of genetic parameters, the estimated heritabilities were moderate (ranged from 0.57 to 0.60). In addition, the estimated genetic correlations of methane production traits with most of carcass traits and feed‐efficiency traits were unfavorable, but those of methane yield traits were favorable or low. For the GWAS, no genome‐wide significant SNP was detected, but a total of four quantitative trait locus (QTL) regions that explained more than 5.0% of genetic variance were localized on the genome, and some candidate genes associated with growth and feed‐efficiency traits were located on the regions. Our results suggest that the predicted methane‐related traits are heritable and some QTL regions for the traits are localized on the genome in Japanese Black steers.     

Effect of dietary crude-protein type on fertilization and embryo quality in dairy cattle

An experiment was conducted to determine whether balancing dietary crude protein for optimal rumen degradability would improve fertilization rate and quality of ova in lactating dairy cows. Thirty-eight Holstein cows in early lactation were fed 1 of 2 diets formulated to be isocaloric and isonitrogenous, containing 16% crude protein. Diet 1 contained 73% rumen degradable intake protein, whereas diet 2 contained 64% rumen degradable intake protein. The cows were induced to superovulate and were inseminated, and ova were recovered nonsurgically on postbreeding day 7. Ova were counted and classified as fertilized or unfertilized. Fertilized ova were scored as excellent, good, fair, poor, or degenerate. Unfertilized ova and poor and degenerate embryos were considered to be nontransferable ova and excellent, good, and fair embryos were considered to be transferable ova. There were no differences for mean number of fertilized, unfertilized, transferable, or nontransferable ova recovered from cows fed the 2 diets (P greater than 0.10). Mean percentage of fertilized ova recovered from cows was greater (P less than 0.05) in those fed diet 2, compared with diet 1. Mean percentage of transferable ova recovered from cows tended to be greater (P = 0.06) in those fed diet 2, compared with diet 1. More cows failed to yield transferable ova (P less than 0.05) when fed diet 1, compared with diet 2. Fertilization failure or early degeneration of embryos may occur in cows fed excess rumen degradable protein.     

New conjugated metabolites of 3-phenoxybenzoic acid in plants

The metabolism of 3-phenoxybenzoic acid, a common plant metabolite of deltamethrin, cypermethrin and fenvalerate, has been studied in abscised leaves of cabbage, cotton, cucumber, kidney bean and tomato plants. The [¹⁴C]-acid was readily converted into more polar conjugates by esterification with glucose, 6-O-malonylglucose, gentiobiose, cellobiose, glucosylxylose and two types of triglucose with different isomerism. Other metabolites identified were the glucosyl ether of 3-(4-hydroxyphenoxy)benzoic acid, and a 3-(2-hydroxyphenoxy)benzoic acid derivative with a total of two molar equivalents of glucose linked to the carboxyl and phenolic -OH groups. The conjugation pathways were somewhat plant-specific. The glucosylxylose ester was found only in cotton, and the cellobiose and triglucose esters were found only in tomato. All of the conjugates except the glucose and glucosylxylose esters were plant metabolites that had not been identified previously. Furthermore, this is the first report to show the presence of cellobiose and triglucose conjugates in plants. However, neither of the acetyl derivatives of the [¹⁴C]-triglucoside was identical with the synthetic deca-acetyl derivative of [1→6]-triglucoside.