Variation in heading date conceals quantitative trait loci for other traits of importance in breeding selection of rice

To identify quantitative trait loci (QTLs) associated with the primary target traits for selection in practical rice breeding programs, backcross inbred lines (BILs) derived from crosses between temperate japonica rice cultivars Nipponbare and Koshihikari were evaluated for 50 agronomic traits at six experimental fields located throughout Japan. Thirty-three of the 50 traits were significantly correlated with heading date. Using a linkage map including 647 single-nucleotide polymorphisms (SNPs), a total of 122 QTLs for 38 traits were mapped on all rice chromosomes except chromosomes 5 and 9. Fifty-eight of the 122 QTLs were detected near the heading date QTLs Hd16 and Hd17 and the remaining 64 QTLs were found in other chromosome regions. QTL analysis of 51 BILs having homozygous for the Koshihikari chromosome segments around Hd16 and Hd17 allowed us to detect 40 QTLs associated with 27 traits; 23 of these QTLs had not been detected in the original analysis. Among the 97 QTLs for the 30 traits measured in multiple environments, the genotype-by-environment interaction was significant for 44 QTLs and not significant for 53 QTLs. These results led us to propose a new selection strategy to improve agronomic performance in temperate japonica rice cultivars.     

评价大米储藏品质的炊饭特性指标的研究

提出了评价大米储藏品质的炊饭特性新指标——光透过率差。实验证明，随着大米品质的劣化，光透过率差明显变小。以此指标为主，结合原有的加热吸水率和ｐＨ值，对因生霉和陈化引起的大米储藏品质的变化，都能较好地进行评价。同时对影响这些指标稳定的实验因素也进行了探讨。     

Quantitative studies on the relationship between plowing into soil of clubbed roots of preceding crops caused by Plasmodiophora brassicae and disease severity in succeeding crops

The effect of the plowing of clubbed roots of cracifers on the population of Plasmodiophora brassicae in soil was quantitatively studied by measuring the number of resting spores produced in the diseased plants. Though the mean number of resting spores per diseased plant increased with the increase of the disease severity, it remained almost identical for the disease severity classified into category 3 among host species and cultivars tested. Mean number of resting spores per diseased plant ranged from 9.3 to 10.9 (log) regardless of the value of the disease index. When the number of resting spores in soil was calculated based on these data and plant cultivation methods, the values were equivalent to 4.8-6.4 resting spores g^-1soil (log)where clubroot disease occurred severely. The value of the disease index of Chinese cabbage plants grown in the pots where clubbed roots of initially grown plants had been plowed into soil (plowing plot) was higher than that in the pots where no plants had been grown (control plot) and where the clubbed roots of initial plants had been removed (removal plot). Though the number of resting spores of P. brassicae in soil decreased by 14% of the inocoKum concentration immediately after the inoculation, the number of spores after the first cultivation in the removal plot was similar to that in the control plot. On the other hand, the number of resting spores in the plowing plot increased significantly compared with that in the control plot. The plowing of clubbed roots into soil resulted in the increase of the population of P. brassicae and disease severity of clubroot in subsequent cultivation in the field. The results corresponded to the values estimated based on the number of resting spores in soil in relation to each value of the disease index.     

The influence of barley malt protein modification on beer foam stability and their relationship to the barley dimeric alpha-amylase inhibitor-I (BDAI-I) as a possible foam-promoting protein

The foam stability of beer is one of the important key factors in evaluating the quality of beer. The purpose of this study was to investigate the relationship between the level of malt modification (degradation of protein, starch, and so on) and the beer foam stability. This was achieved by examining foam-promoting proteins using two-dimensional gel electrophoresis (2DE). We found that the foam stability of beer samples brewed from the barley malts of cultivars B and C decreased as the level of malt modification increased; however, the foam stability of cultivar A did not change. To identify the property providing the increased foam stability of cultivar A, we analyzed beer proteins using 2DE. We analyzed three fractions that could contain beer foam-promoting proteins, namely, beer whole proteins, salt-precipitated proteins, and the proteins concentrated from beer foam. As a result, we found that in cultivar A, some protein spots did not change in any of these three protein fractions even when the level of malt modification increased, although the corresponding protein spots in cultivars B and C decreased. We analyzed these protein spots by peptide mass finger printing using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. As a result, all of these spots were identified as barley dimeric alpha-amylase inhibitor-I (BDAI-I). These results suggest that BDAI-I is an important contributor to beer foam stability.     

Simultaneous gas chromatographic determination of dibutyltin and tributyltin compounds in biological and sediment samples

A method is described for the simultaneous determination of nanogram amounts of dibutyltin and tributyltin compounds in biological and sediment samples. These compounds are converted to the corresponding chlorides with HCl, extracted with ethyl acetate-hexane (3 + 2) for biological samples and with hexane for sediment samples, and hydrogenated with sodium borohydride. The corresponding hydrides, Bu2SnH2 and Bu3SnH, are detected by electron-capture gas chromatography after cleanup by silica gel column chromatography. Detection limits are 1.0-2.0 and 0.5-1.0 ng/g, respectively, for biological and sediment samples.     

An improved method for bright-field imaging of arbuscular mycorrhizal fungi in plant roots

Easy observation methods to assess the colonization levels of arbuscular mycorrhizal (AM) fungi in plant roots are crucial for studying the biology of AM symbiosis and for considering agricultural use. Many AM studies employ Trypan Blue (TB) coupled with lactic acid to stain AM fungal structures as bright-field images; however, TB staining can be difficult to use owing to its noxiousness and high viscosity. Here, we report the development of an easy method for visualizing AM fungal structures as bright-field images using 3,3′-diaminobenzidine (DAB). Wheat germ agglutinin (WGA)-conjugated horseradish peroxidase (HRP), which specifically targets N-acetylglucosamine polymers and detects AM fungal cell walls, penetrated the cortical layers of 10% potassium hydroxide (KOH)-treated soybean roots and stained AM fungal mycelia in the presence of DAB and hydrogen peroxide (H₂O₂). Comparison between DAB and TB staining of soybean (Glycine max L.) roots suggested that the intactness of root systems and image contrast using DAB staining were superior. Background signals in stele observed by DAB staining were negligible as compared with those observed by WGA-fluorescein isothiocyanate staining. DAB staining, which combines the advantages of TB (easy bright-field imaging) and WGA-fluorophore (specific and high-quality) staining, provides a robust imaging method for macro- and micro-level analyses of AM roots and is applicable to at least six crops: soybean, onion (Alium cepa L.), potato (Solanum tuberosum L.), maize (Zea mays L.), rice (Oryza sativa L.), and sunflower (Helianthus annuus L.).     

Simultaneous gas chromatographic determination of carboxylic acids in soft drinks and jams

A method was developed for simultaneous gas chromatographic determination of sorbic acid, dehydroacetic acid, and benzoic acid used as preservatives, and succinic acid, fumaric acid, malic acid, and tartaric acid used as acidulants in soft drinks and jams. A sample was dissolved in NH4OH-NH4Cl pH 9 buffer solution, and an aliquot of the solution was passed through a QAE-Sephadex A 25 column. The column was washed with water, and the carboxylic acids were eluted with 0.1N HCl. Sorbic acid, dehydroacetic acid, and benzoic acid were extracted with ethyl ether-petroleum ether (1 + 1), and determined on a 5% DEGS + 1% H3PO4 column. Succinic acid, fumaric acid, malic acid, and tartaric acid in the lower layer were derivatized with N,O-bis(trimethylsilyl)acetamide and trimethylchlorosilane, and determined on a 3% SE-30 column. Recoveries from soft drink and jam samples fortified with 0.1% each of 7 carboxylic acids ranged from 92.4 to 102.6% for preservatives, and from 88.1 to 103.2% for acidulants.