Regulation of root-to-leaf Na and Cl transport and its association with photosynthetic activity in salt-tolerant soybean genotypes

ABSTRACT

Soil salinity is a major constraint to sustainable crop production. Genetic improvements are needed for growing soybean in salinity-prone environments. Salt-tolerant soybean genotypes alleviate a reduction in photosynthesis and growth under saline conditions; however, the detailed mechanisms involved remain unclear. Here, we aimed to clarify how Na and Cl root-to-leaf transport is quantitatively regulated, and to identify whether photosynthetic tolerance depends on traits associated with either stomata or with mesophyll tissues. Two pairs of pot-grown soybean near-isogenic lines (NILs) consisting of tolerant and susceptible counterparts, derived from a cross between salt-tolerant FT-Abyara and salt-sensitive C01, were subjected to salinity treatment in a rainout greenhouse. Comparison of photosynthetic responses between genotypes indicated that genotypic differences in salinity tolerance depended on the ability for sustained CO₂ assimilation in mesophyll tissues, rather than stomatal conductance. The ratio of photosynthetic rate to intercellular CO₂ concentration (A/Ci) declined exponentially with increasing Na and Cl concentration regardless of genotype, but tolerant genotypes effectively kept both elements at significantly low levels. Under saline conditions, tolerant genotypes reduced Na and Cl content at the two transport pathways: from root to stem, and from stem to leaf, but the reduction of Cl at each pathway was only minor. These results suggest that integrating genetic capacity for Cl transport regulation and osmotic adjustment should be an important target in salinity-tolerance soybean breeding.     

Purification and characterization of two anionic trypsins from the hepatopancreas of carp

SUMMARY: Two trypsins, designated as trypsin A and trypsin B, have been purified from the hepatopancreas of carp. The purification procedures consisted of ammonium sulfate fractionation, and chromatographies on DEAE-Sephacel, Ultrogel AcA54 and Q-Sepharose. Trypsin A was purified to homogeneity with the molecular mass of approximately 28 kDa, while trypsin B gave two close bands of 28.5 kDa and 28 kDa on sodium dodecylsulfate polyacrylamide gel electrophoresis both under reducing and non-reducing conditions. On native-PAGE, both trypsin A and trypsin B showed a single band. Trypsin A and trypsin B revealed optimum temperature of 40°C and 45°C, respectively, and shared the same optimum pH 9.0 using Boc-Phe-Ser-Arg-MCA as substrate. Both enzymes were effectively inhibited by trypsin inhibitors and their susceptibilities were similar. The NH₂-terminal amino acid sequences of trypsin A and trypsin B were determined to 37th and 40th amino acid residue, respectively. Their sequences were very homologous, but not identical to that of a trypsin-type serine proteinase from carp muscle and these of other trypsins. Immunoblotting test using the antibody raised against trypsin A cross-reacted with trypsin B positively.     

Regression tree analysis of the relationship between the concentrations of antimicrobial components and the microbiota of normal milk from dairy cows

The purpose of this study was to determine the concentrations of antimicrobial components (immunoglobulin A (IgA), lactoferrin (LF), lingual antimicrobial peptide (LAP), and S100A7) in normal milk and their relation to host factors (Age, somatic cell count (SCC), days in milk, richness, and alpha diversity of the milk microbiota) in dairy cows using multivariate regression tree analyses, and to clarify how the milk microbiota is related to the obtained results. Thirty normal milk samples were collected from a commercial dairy farm in June 2020. The thresholds that predicted the concentration of each antimicrobial component in milk were obtained by regression tree analysis, and the beta-diversity of the milk microbiota composition between groups divided according to each threshold was compared by an analysis of similarities test. The IgA and LF concentrations were mainly predicted by the SCC (177,500 and 70,000 cells/ml, respectively), and the LAP and S100A7 concentrations were predicted by Age (29.667 and 40.3 months, respectively). No relationship was observed between the concentration of IgA, LAP, or S100A7 and the milk microbiota composition between the groups divided by the threshold for prediction, but the milk microbiota composition was significantly different between the groups divided by the threshold for predicting the LF concentration. Our results indicated that the LF concentration in normal milk may be associated with the milk microbiota composition.     

Studies on availability and fixation of phosphorus in soil (part 4)

It Is known that inorganic phosphorus is contained in soil mainly in the form of calcium phosphates, aluminium phosphates and iron phosphates.     

Prediction of grain protein content in winter wheat through leaf color measurements using a chlorophyll meter

A field trial was conducted over a 3-year period at the Hokkaido Kitami Agricultural Experiment Station to examine whether the grain protein content (GPC) of a winter wheat cultivar (Triticum aestivum L. cv. Chihokukomugi) suitable for Japanese noodle-making could be predicted before harvest. The prediction of the GPC was accurate based on the color of the second leaf (just below the flag leaf) at the end of the emergence of the inflorescence, when nitrogen application was graded. In order to evaluate the reliability of this test, a survey of 95 wheat fields in the eastern part of Hokkaido was also carried out during a 3-year period. The prediction of the GPC for this cultivar based on the color of the second leaf was less accurate across many sites. The results of this survey, however, suggested that the leaf color could be used as an index for ranking the GPC as low or high in relation to processing requirements. When the leaf color value of the second leaf measured with a chlorophyll meter at the end of the emergence of the inflorescence was less than 40, it was predicted that the GPC would be lower than the processing requirement. This index could be applied to the cultivars grown in the eastern part of Hokkaido, except for those grown on peat soils.     

Characterization of the morphological,physical, and mechanical properties of seven nonwood plant fiber bundles

The morphological, physical, and mechanical properties of the nonwood plant fiber bundles of ramie, pineapple, sansevieria, kenaf, abaca, sisal, and coconut fiber bundles were investigated. All fibers except those of coconut fiber had noncircular cross-sectional shapes. The crosssectional area of the fiber bundles was evaluated by an improved method using scanning electron microscope images. The coefficient factor defined as the ratio of the cross-sectional area determined by diameter measurement, to the cross-sectional area determined by image analysis was between 0.92 and 0.96 for all fibers. This indicated that the area determined by diameter measurement was available. The densities of the fiber bundles decreased with increasing diameters. The diameters of each fiber species had small variation of around 3.4%-9.8% within a specimen. The tensile strength and Young’s modulus of ramie, pineapple, and sansevieria fiber bundles showed excellent values in comparison with the other fibers. The tensile strength and Young’s modulus showed a decreasing trend with increasing diameter of fiber bundles.     

Mutagenesis, heterogeneous gene expression, and purification and amino acid substitution analyses of plant peroxidase, PrxA3a

We introduced mutations into prxA3a, a peroxidase gene of hybrid aspen, Populus kitakamiensis, to substitute the amino acid residues at the surface of the protein, and analyzed substrate specificities. PrxA3a and mutated enzymes heterogeneously gene expressed in Saccharomyces cerevisiae were purified by Ni affinity chromatography, hydrolysis of sugar chain (Endoglycosidase H_f) and gel filtration. The substrate specificities were altered by substituted amino acid residues. PrxA3a F77Y A165W acquired the substrate specificity to m-chlorophenol. PrxA3a F77Y and PrxA3a F77YA165W could polymerize sinapyl alcohol. In addition, PrxA3a A165W, F77Y, and F77YA165W improved cytochrome c oxidizing activity. These substituted amino acid residues should function as a catalytic site outside of the heme pocket.     

Habitat modification by invasive crayfish can facilitate its growth through enhanced food accessibility

Background

Invasive ecosystem engineers can facilitate their invasions by modifying the physical environment to improve their own performance, but this positive feedback process has rarely been tested empirically except in sessile organisms. The invasive crayfish Procambarus clarkii is an ecosystem engineer that destroys aquatic macrophytes, which provide a physical refuge for animal prey, and this destruction is likely to enhance vulnerability to predators. Using two series of mesocosm experiments, we tested the hypothesis that the invasive crayfish increases its feeding efficiency on animal prey by reducing submerged macrophytes, thus increasing its individual growth rate in a positive density-dependent manner.

Results

In the first experiment, increasing crayfish density reduced both macrophytes and animal prey (dragonfly and chironomid larvae) and, importantly, increased the growth rate of individual crayfish, in accordance with our expectation. In the second experiment, we used artificial macrophytes to clarify whether the physical architecture of macrophytes itself protects animal prey and limits crayfish growth rate. Increasing the artificial macrophyte quantity not only increased the survival of animal prey, but also retarded the crayfish growth rate.

Conclusions

We conclude that macrophytes strengthen bottom-up control of crayfish, but this effect can be relaxed by increasing the density of crayfish via reduction in macrophytes. This positive feedback process may explain the crayfish outbreaks and regime shifts occasionally observed in invaded freshwater ecosystems.

     

Lactoferrin concentrations in milk from normal and subclinical mastitic cows

The concentrations of lactoferrin (Lf) in quarter milk from normal lactating cows and subclinical mastitic cows were measured to determine whether the Lf concentration in milk is influenced by the age of the cow, the stage of lactation, number of milk somatic cells and the presence of pathogens. Lf concentrations in 111 quarter milk samples from 28 normal lactating cows and 270 quarter milk samples from 198 subclinical mastitic cows were measured by means of a single radial immunodiffusion test. Lf concentrations (means +/- standard deviations; logarithmic form) in normal cows and subclinical mastitic cows were 2.23 +/- 0.39 and 2.70 +/- 0.39, respectively. The mean milk Lf concentration (log) in subclinical mastitic cows was significantly (p<0.01) higher than that in normal cows. The mean milk Lf concentration (log) in normal lactating cows aged 5 years was lower than those in normal lactating cows aged 2 years (p<0.01) and 3 years (p<0.05). The results showed that the milk Lf concentration (log) is associated with age of the dairy cow (one-way analysis of variance test, p<0.01). The mean milk Lf concentration (log) in the latter lactational period tended to be higher than those in the peak and middle periods. Milk Lf concentrations (log) tended to be proportional to the level of the somatic cell count (SCC) score. Mean milk Lf concentrations (log) in subclinical mastitic cows infected with Staphylococcus aureus and with other streptococci species were significantly (p<0.01) higher than those in cows infected with coagulase-negative staphylococci and with Corynebacterium bovis.     

Discrimination of three amphistome species by PCR-RFLP based on rDNA ITS2 markers

Three bovine amphistomes, Calicophoron calicophorum, Orthocoelium streptocoelium and Homalogaster paloniae, are common in Japan. This study was carried out to describe ITS2 sequences in the 3 species, and to evaluate a PCR-RFLP technique based on ITS2 sequence for the species identification in single eggs of the parasites. The ITS2 sequences of the three species contained 19 variable sites including one gap. The sequence difference between species was 4.2-5.3%. The three species of amphistomes were identified based on the difference in the restriction sites of Acc II on the ITS2 sequence.