Genetic analysis of β-amylase thermostability to develop a DNA marker for malt fermentability improvement in barley, Hordeum vulgare

β‐Amylase thermostability is one of the major factors affecting fermentability in the brewing process; consequently, it could be used as a selection marker for the trait. In order to clarify what controls its thermostability, the linkage analysis of β‐amylase thermostability and its genotype as restriction fragment length polymorphism patterns was performed in three cross populations. Then, β‐amylase cDNAs cloned from the three varieties which had a different thermostability type were expressed in Escherichia coli. According to the results of the linkage analysis and gene expression test, it was concluded that β‐amylase thermostability resulted from a difference in its structural gene. Furthermore, to construct an STS marker for the gene, the gDNA sequences of β‐amylase were compared among the three varieties, which had different thermostabilities. Although there were many differences in the intron sequence, few nucleotides differed in the exon region. Based on the variation in the intron region, a sequence‐tagged‐site marker was constructed to detect β‐amylase genotypes in breeding material.     

Effect of CO2 enrichment on fruit growth and quality in Japanese pear (Pyrus serotina Reheder cv. Kosui)

Six year-old Japanese pear (Pyrus seratina Reheder cv. Kosui) trees grafted on P. serotina cv. Nihonyamanashi were grown in containers filled with Granite Regosol under glasshouse conditions. At different stages of fruit growth, pear trees were exposed to an elevated CO₂ concentration (130 Pa CO₂ ) along with a control (35 Pa CO₂). For one group of plants, CO₂ enrichment was applied for 79 d from 52 d after full bloom (DAB) to fruit maturity (long-term CO₂ enrichment) and for another group the same treatment was applied for 35 d from 96 DAB to fruit maturity (short-term CO₂ enrichment). The effects of the elevated CO₂ concentration on vegetative growth, mineral contents, and fruit production and quality were examined. Long-term CO₂ enrichment enhanced vegetative growth, without any significant effect on the mineral contents in either flower bud or fruit except for a remarkable increase in the K content. Long-term CO₂ enrichment increased the fruit size and fresh weight, but had no significant effect on the fruit quality. On the other hand, the short-term CO₂ enrichment did not induce any significant change in the fruit size but increased the fruit sugar concentration. Along with the reduction of the sorbitol concentration in fruit, the fructose and sucrose concentrations increased and these changes occurred earlier at elevated CO₂ than at ambient CO₂ concentrations. From these results, we concluded that the effect of CO₂ enrichment on fruit growth varies depending upon the growth stages of fruit: during the initial and fruitlet stages when fruit expansion occurs, CO₂ enrichment increases the fruit size, whereas, during maturation when fruit expansion has slowed down and sugar accumulation in fruit is active, it increases the fruit sugar concentration.     

Interactions between different genotypic tissues in citrus graft chimeras

The heritability of tolerance of wheat F₃ lines to competition from annual ryegrass (Lolium rigidum), and its relationship to morphological traits, were determined using crosses between wheat cultivars with good and poor competitive ability. Forty F₂-derived F₃ lines from a cross between two late flowering varieties (Machete × Spear) and 40 from a cross between early flowering varieties (Wilgoyne × Gutha) were grown in the field with and without annual ryegrass. There was significant genetic variation between lines within each of the two populations in a number of aspects of plant growth and development, including yield in monoculture. The estimates of heritability for % yield loss due to competition were 0.25 and 0.57 in the two crosses respectively, indicating that selection for high tolerance to competition in the F₃ generation or later should be effective. Fairly strong relationships between height and % yield loss and between leaf length and % yield loss suggest that these may be useful auxiliary traits when selecting for low % yield loss. However, differences between crosses in the magnitude and sign of genetic and phenotypic correlation between traits indicate that competitive ability is a complex character influenced by many factors. This revised version was published online in August 2006 with corrections to the Cover Date.     

Characterizing Submergence Survival Strategy in Rice Via Chlorophyll Fluorescence

Rice plants cope with flash floods using either an ‘escape strategy’ involving rapid shoot elongation or a ‘quiescence strategy’ involving survival underwater with minimal activity. To clarify the differences in the response of leaf photosynthesis properties to conditions during and after submergence, two rice cultivars were compared: a non‐shoot‐elongating cultivar IR 67520‐B‐14‐1‐3‐2‐2 (IR67520) and a shoot‐elongating cultivar IR72442‐6B‐3‐2‐1‐1 (IR72442). Twenty‐three‐day‐old seedlings were submerged in 80‐cm‐deep water for 14 days. During submergence, the chlorophyll contents of the upper fully expanded leaf (5th leaf) and newly developed leaf later (6th leaf) and the maximal quantum yield of photosystem II (F_v/F_m) of the fifth leaf decreased earlier in IR72442 than in IR67520. In the submerged sixth leaf, F_v/F_m was higher in IR72442 than in IR67520 at early measurement. Although F_v/F_m of the sixth leaf in submerged IR67520 increased substantially from 2 days post‐submergence, IR72442 decreased because of leaf chlorosis. Therefore, a non‐shoot‐elongating cultivar coped with submergence by inhibiting photodamage and maintaining high chlorophyll content in the leaves. The shoot‐elongating cultivar was able to maintain the photosynthetic capacity of the newly developed leaf during submergence by prompt reduction of chlorophyll and chlorophyll fluorescence in the leaf that developed before submergence.     

Evaluation of fresh pasta-making properties of extra-strong common wheat (Triticum aestivum L.)

The relationship between characterictics of flour of common wheat varieties and fresh pasta-making qualitites was examined, and the fresh pasta-making properties of extra-strong varieties that have extra-strong dough were evaluated. There was a positive correlation between mixing time (PT) and hardness of boiled pasta, indicating that the hardness of boiled pasta was affected by dough properties. Boiled pasta made from extra-strong varieties, Yumechikara, Hokkai 262 and Hokkai 259, was harder than that from other varieties and commercial flour. There was a negative correlation between flour protein content and brightness of boiled pasta. The colors of boiled pasta made from Yumechikara and Hokkai 262 grown under the condition of standard manuring culture were superior to those of boiled pasta made from other varieties. Discoloration of boiled pasta made from Yumechikara grown under the condition of heavy manuring culture was caused by increase of flour protein content. On the other hand, discoloration of boiled pasta made from Hokkai 262 grown under the condition of heavy manuring culture was less than that of boiled pasta made from Yumechikara. These results indicate that pasta made from extra-strong wheat varieties has good hardness and that Hokkai 262 has extraordinary fresh pasta-making properties.     

Strong antiviral activity of heated and hydrated dolomite--preliminary investigation

Heated and hydrated naturally occurring dolomite showed very strong antiviral activity. Infectivity of avian and human influenza, avian infectious bronchitis (coronavirus), Newcastle disease (paramyxovirus) and avian laryngotracheitis (herpesvirus) viruses dropped at least 1,000 fold following contact with the dolomite for five minutes at 4 degrees C. Dolomite is expected to be useful to inhibit the incidence of emerging and re-emerging infectious diseases.     

Combination of lipids and emulsifiers enhances the absorption of orally administered quercetin in rats

The effects of lipids, emulsifiers, and ethanol on the absorption of orally administered quercetin in rats were investigated for its efficient intestinal absorption. Rats were administered 150 micromol/kg quercetin in water supplemented with lipids and/or emulsifiers, or ethanol, and blood was collected from the tail for 6 h after administration. Co-administration of lipids such as lecithin and soybean oil or emulsifiers including sucrose fatty acid ester, polyglycerol fatty acid ester, and sodium taurocholate had no statistically significant effects on quercetin absorption, although these constituents rather increased the accumulation of conjugated forms of quercetin and those of isorhamnetin in rat plasma. However, the combination of lipids and emulsifiers enhanced the absorption of quercetin significantly. Thirty and fifty percent (v/v) of the ethanol in the vehicle raised the efficiency of quercetin absorption in a concentration-dependent manner. Quercetin absorption-enhancing effects of these constituents seemed to be affected by quercetin's solubility in respective vehicles used for the administration. Ethanol is not helpful for the effective absorption of quercetin, as a high concentration is required. In conclusion, a combination of lipids and emulsifiers is necessary for enhancing quercetin absorption.     

Root-shoot interaction as a limiting factor of biomass productivity in new tropical rice lines

The objective of the present study was to identify the limiting factors in biomass productivity of new tropical rice lines (panicle weight type) by analyzing the relationship between root and shoot activity. Five field experiments using three new lines, IR65598-112-2, IR65600-42-5-2, and IR68544-29-2-1-3-1-2, and one of the highest-yielding indica rice varieties (panicle number type), IR72, were conducted at the International Rice Research Institute from 1997 to 2002. Specific absorption rate of N (SARN , mg N g^-1 root dry weight d^-1), specific stem sap exudation rate (sap exudation rate, g exudate g^-1 root dry weight 12 h^-1) and specific root respiratory rate (root respiratory rate, μmol O₂ g^-1 root dry weight h^-1) were determined as indices of root activity. Relative growth rate (RGR, mg g^-1 d^-1) was used as an index of shoot activity. Compared with IR72, the new lines showed lower RGR and SAR_N values during the early growth stages. In contrast, during the late growth stages, these activities were higher in the new lines than in IR72. The SAR_B and sap exudation rate showed a linear correlation with RGR at successive growth stages, regardless of the genotypes and growth conditions. These findings indicated that active root-shoot interaction was maintained throughout the growth period in high-yielding tropical rice, including the new lines and IR72. Therefore, it was considered that SAR_N and the sap exudation rate are useful indices of root activity regulating RGR in the new lines. However, the root respiratory rate could not be used for selection, because the relationship between RGR and the root respiratory rate changed with the growth conditions. Our findings support the hypothesis that root and shoot activities during maturation are important factors affecting the productivity of the new lines, which have not yet been able to attain the targeted yield.