Resistance Evaluation of Some Hybrid Rice, Conventional Early Indica and Late Japonica Rice to Magnaporthe grisea

Thirty isolates of Magnaporthe grisea collected from 18 provinces/cities representing 21 pathotypes and 9 different lineages were inoculated to rice varieties with known resistance genes and some hybrid rices,conventional early indica and late japonica varieties cultivated recently in China.Virulence spectrum of the 30 isolates was very different,showing that they recognize numerous different resistance genes.Varieties also revealed very different resistance patterns showing that they carry different resistance genes or combinations of resistance genes.On the basis of comparisons with international differential varieties with known resistance genes,resistance genes in certain Chinese varieties could be speculated.The results indicated that some of them were resistant to most of the isolates tested and that they could be of interest as resistance sources for hybrid parents or to be planted in the field directly.     

Elastic domains regulate growth and organogenesis in the plant shoot apical meristem

Although genetic control of morphogenesis is well established, elaboration of complex shapes requires changes in the mechanical properties of cells. In plants, the first visible sign of leaf formation is a bulge on the flank of the shoot apical meristem. Bulging results from local relaxation of cell walls, which causes them to yield to internal hydrostatic pressure. By manipulation of tissue tension in combination with quantitative live imaging and finite-element modeling, we found that the slow-growing area at the shoot tip is substantially strain-stiffened compared with surrounding fast-growing tissue. We propose that strain stiffening limits growth, restricts organ bulging, and contributes to the meristem's functional zonation. Thus, mechanical signals are not just passive readouts of gene action but feed back on morphogenesis.     

Variation and phylogeny of the ribosomal DNA unit types and 5 S DNA inPetunia Jussieu

Summary Seven wildPetunia species including 2n = 18 species (P. parviflora Jussieu,P. linearis Hook.) and those with 2n = 14 (P. parodii Steene,P. axillaris Lam.,P. integrifolia Hook.,P. inflata R.E. Fries,P. violacea Lindl.) and tenPetunia hybrida horticultural lines were compared for polymorphisms in rDNA genes using the four restriction enzymesEcoRI,BamHI,HindIII andXhoI. All the unit types found in the lines pre-existed in the wild forms. There are two different sizes of either 11.45 or 11.6 kb./The 2n = 18 species are closely related to the 2n = 14 species, thus making thePetunia genus homogeneous. Moreover, it is likely thatP. hybrida lines originated in several kinds of crosses between these species. We constructed a dendrogram for all the 15 rDNA unit types found. Two main branches of the tree result from the presence or the absence ofHindIII sites. The main branch is divided according to variability at theEcoRI andBamHI sites. Taking into account the existence of several loci which carry one unit type only, we consider whether or not exchanges might occur between loci. Lines carrying two unit types and lines carrying three unit types support such a hypothesis.XhoI andBamHI fragments enable us to distinguish two types of 5S DNA corresponding to 2n = 18 and 2n = 14 species, respectively.P. hybrida lines and each 2n = 14 wild species carry one of the types only, that corresponds to one 5S DNA locus. The most parsimonious phylogenetic trees whatever the species chosen as the outgroup, do not fit with our knowledge ofPetunia and with taxonomy. This is likely because only few loci formed the basis of these phylogenetic constructions.     

Utilization of near infrared reflectance spectroscopy (NIRS) to quantify the impact of earthworms on soil and carbon erosion in steep slope ecosystem: A study case in Northern Vietnam

This work focuses on a new approach to quantify the effects of above-ground earthworm's activity on soil erosion in steep slope ecosystems such as in Northern Vietnam. In these areas and in many others in the world, soil erosion becomes a major issue while the factors that determine it are still misunderstood. Earthworm's activity is believed to influence soil erosion rate, but we are still unable to precisely quantify their contribution to soil erosion. In this study, we used Near Infrared Reflectance Spectroscopy (NIRS) to quantify the proportion of soil aggregate in eroded soil coming from earthworm activity. This was done by generating NIRS signatures corresponding to different soil surface aggregates (above-ground soil casts produced by earthworms vs. surrounding topsoil).     

Quantification of vertical solid matter transfers in soils during pedogenesis by a multi-tracer approach

Purpose

Vertical transfer of solid matter in soils (bioturbation and translocation) is responsible for changes in soil properties over time through the redistribution of most of the soil constituents with depth. Such transfers are, however, still poorly quantified.

Materials and methods

In this study, we examine matter transfer in four eutric Luvisols through an isotopic approach based on ¹³⁷Cs, ²¹⁰Pb_(xs), and meteoric ¹⁰Be. These isotopes differ with respect to chemical behavior, input histories, and half-lives, which allows us to explore a large time range. Their vertical distributions were modeled by a diffusion-advection equation with depth-dependent parameters. We estimated a set of advection and diffusion coefficients able to simulate all isotope depth distributions and validated the resulting model by comparing the depth distribution of organic carbon (including ^12/13C and ¹⁴C isotopes) and of the 0–2-μm particles with the data.

Results and discussion

We showed that (i) the model satisfactorily reproduces the organic carbon, ¹³C, and ¹⁴C depth distributions, indicating that organic carbon content and age can be explained by transport without invoking depth-dependent decay rates; (ii) translocation partly explains the 0–2-μm particle accumulation in the Bt horizon; and (iii) estimates of diffusion coefficients that quantify the soil mixing rate by bioturbation are significantly higher for the studied plots than those obtained by ecological studies.

Conclusions

This study presents a model capable of satisfactorily reproducing the isotopic profiles of several tracers and simulating the distribution of organic carbon and the translocation of 0–2-μm particles.

     

Determination of the heat treatment undergone by milk by following the denaturation of alpha-lactalbumin with a biosensor

Dairy industries are interested in knowing the heat treatment undergone by milk so as to control the quality of drinking milks or to control their heating systems. Among the different techniques available to characterize the heat treatment of milk, estimation of the denaturation of proteins has been widely used. However, because the concentration of the proteins in raw milk can fluctuate significantly, determining only the concentration of a native protein without knowing its concentration in the raw milk before undergoing heat treatment can lead to significant imprecision. The objective of this study was to develop, on Biacore 3000, a biosensor assay for determining the denaturation index of alpha-lactalbumin by quantifying separately the native and "heat-denatured" forms of alpha-lactalbumin with specific monoclonal antibodies. alpha-Lactalbumin denaturation index is independent of the concentration of alpha-lactalbumin in the original raw milk. The technique developed is discriminating, fast, repeatable, fully automated, and requires no pretreatment of the milk sample.     

Assessment of cocoa input needs using soil types and soil spectral analysis

In this study, diffuse reflectance spectroscopy (DRS) approach was examined for making input recommendations in the smallholder cocoa farms of Papua New Guinea (PNG). Soil samples were collected from four provinces of PNG. Soil samples from four different depths (0–10, 10–30, 30–60 and 60–90 cm) of 32 profiles in each of these site were used to create a database of soil chemical and physical properties. Spectral reflectance values at 1 nm interval covering visible to shortwave‐infrared (350–2,500 nm) were collected for each of these soil samples to develop partial least squares regression models. Soil textural fractions, soil organic carbon contents and available N were well predicted by the DRS approach with R² values larger than 0.75. Moderate to poor estimation efficiencies were observed for remaining parameters. Nevertheless, the estimated soil attributes and their corresponding measured soil parameters were used as inputs to an input recommendation model of soil diagnosis to create input recommendation for a targeted cocoa yield of 1,000 kg dry cocoa beans ha^‐1 Resulting input recommendations were similar for both of these input sources (measured and DRS‐estimated) suggesting that the DRS approach may provide an easy way to create input recommendations.     

Subsoil improvement in a tropical coarse textured soil: Effect of deep-ripping and slotting

In many coarse textured soils, limited root development and biomass production are attributed to adverse physical conditions in the subsoil. The current study was undertaken on an Arenic Acrisol located in Northeast Thailand (i) to assess whether subsoil physical characteristics influence crop rooting depth, and (ii) to compare the benefits associated with conventional tillage with that of localised subsoil loosening on crop performance and selected soil attributes. Control plots consisted of disk ploughing; the implemented treatments were conventional deep-ripping and localised slotting below the planting line. A crop rotation consisting of a legume followed by maize was established annually to assess the impact of these treatments on crop performance. In the control treatment, root development was restricted to the topsoil (0–20 cm) due to high subsoil bulk density (>1.6 Mg m⁻³). After deep-ripping, no improvement was observed in bulk density, rooting depth and in crop performance. The implementation of a slotting treatment systematically improved root development in the slotted subsoil, root impact frequency increasing from <0.2 to 0.6–0.8 (P = 0.01) despite no change in the bulk densities of the subsoil. This systematic improvement in root development could be explained by (i) reduced slumping that enable root development prior to recompaction and/or (ii) preferential drainage in the slot and therefore decreased resistance to root penetration. In a dry year maize yield was improved by 78% (P = 0.01); the deep-rooting legume Stylosanthes was tested only a wet year and its biomass production increased by >40% (P = 0.03). This study highlights the detrimental impact of subsoil compaction on root development and the potential role of slotting in coarse textured soils as a long-term management tool in addressing adverse subsoil physical characteristics that limit deep-rooting.     

Topography of the casein micelle surface by surface plasmon resonance (SPR) using a selection of specific monoclonal antibodies

Several theoretical models of the casein micelle structure have been proposed in the past, but the exact organization of the four individual caseins (α(s1), α(s2), β, and κ) within this supramolecular structure remains unknown. The present study aims at determining the topography of the casein micelle surface by following the interaction between 44 monoclonal antibodies specific for different epitopes of α(s1)-, α(s2)-, β-, and κ-casein and the casein micelle in real time and no labeling using a surface plasmon resonance (SPR)-based biosensor. Although the four individual caseins were found to be accessible for antibody binding, data confirmed that the C-terminal extremity of κ-casein was highly accessible and located at the periphery of the structure. When casein micelles were submitted to proteolysis, the C-terminal extremity of κ-casein was rapidly hydrolyzed. Disintegration of the micellar structure resulted in an increased access for antibodies to hydrophobic areas of α(s1)- and α(s2)-casein.