Structural and physiological changes associated with the skin spot disorder in apple     

Eckhard GrimmBishnu P. Khanal  Andreas WinklerMoritz Knoche  Dirk Köpcke 《Postharvest Biology and Technology》2012,64(1):111-118

Skin spot is an important physiological disorder of ‘Elstar’ apples (Malus × domestica Borkh.) that occurs after fruit have been removed from controlled atmosphere storage. Skin spots are irregular patches of small, round, brown blemishes. Cross-sections reveal a browning of protoplasts (coagulated) and of cell walls that extends into the hypodermis. Skin spots are always associated with linear, gaping and non-gaping microcracks in the cuticle. Staining of apple skin with calcofluor white usually results in white fluorescence of cell walls but, within a skin spot, the white fluorescence is weak or absent. Cell walls within, and in the immediate vicinity of skin spots stain with phloroglucin/HCl indicating the presence of lignin. The area of skin affected by skin spots was positively and linearly correlated with the area of the non-blush fruit surface infiltrated by acridine orange. In general, skin spots were limited to the non-blush fruit surface and occurred more frequently near the stem-end than the calyx region of the fruit. Skin spot areas were correlated with a 2.5-fold increase in water vapour permeability compared with unaffected areas (23.8 ± 4.0 m s⁻¹ with skin spots, 9.6 ± 2.1 × 10⁻⁵ m s⁻¹ without skin spots). Strips of the fruit skin from regions with skin spots had an increased maximum force and modulus of elasticity. Dipping fruit in ascorbic acid (0.1 or 0.3 mM for 10 min) before storage decreased the area affected by skin spots. There was no effect of dipping in ethanol/water (70%, v/v, 15 min) or in solutions of captan (1.5 g L⁻¹, 10 min) or trifloxystrobin (0.1 g L⁻¹, 10 min). In contrast, prestorage treatment with 1-methylcyclopropene (630 nL L⁻¹ for 24 h) or poststorage incubation in H₂O₂ (10% for 2, 6, 10 and 16 h) increased skin spots. Our data are consistent with a typical cell response to an oxidative burst that seems to be focussed on particular regions of the ‘Elstar’ fruit surface by concentrations of cuticular microcracks, and that is possibly caused by reoxygenation injury upon removal from CA storage.  相似文献   

Identification of quantitative trait loci (QTLs) associated with maintenance of wheat (Triticum aestivum Desf.) quality characteristics under heat stress conditions     

Francis W. Beecher  Esten Mason  Suchismita Mondal  Joseph Awika  Dirk Hays  Amir Ibrahim 《Euphytica》2012,188(3):361-368

The goal of this study was to identify quantitative trait loci (QTLs) associated with the maintenance of wheat grain quality following post-anthesis heat stress in a recombinant inbred line (RIL) population. The response to heat stress was measured using the sodium dodecyl sulfate sedimentation test (SDSS), a significant predictor of bread baking quality. SDSS scores were used to identify QTLs associated with grain quality and QTLs associated with quality stability were identified based on percent change in SDSS score between the heat stress and control treatments. Four QTLs were identified, located one each on linkage groups 1B, 1D, 4A, and 7A. The 1B, 1D, and 4A QTLs were associated with grain quality; the QTL on linkage group 7A was associated with quality stability. To confirm the detected QTLs, eighty advanced lines grown at three Texas nurseries were tested for relationships between allelic polymorphism at QTL linked markers and quality traits. Quality trait stability in the advanced lines was estimated using the coefficient of variability (CV%) of quality traits between nurseries. The analysis supported the relationship of the predicted QTLs on linkage groups 1B, 1D, and 4A with quality traits. The confirmed QTLs may be used in marker assisted selection (MAS) to develop wheat lines possessing superior quality traits. In addition, identification of genetic regions associated with this trait will aid the identification of the underlying genes.  相似文献   

Vp1 expression profiles during kernel development in six genotypes of wheat, triticale and rye     

Sarah De Laethauwer  Dirk Reheul  Jan De Riek  Geert Haesaert 《Euphytica》2012,188(1):61-70

During the last few decades, the physiological and genetic background of dormancy, and correlated pre-harvest sprouting (PHS) have been intensively investigated. Special attention has often been paid to genetic factors that may explain and predict PHS susceptible behaviour. A major candidate is the Vp1 gene which is involved in embryo development and maturation as well as in dormancy establishment. In this study, Vp1 gene expression during kernel development was studied in wheat, triticale and rye as a potential biomarker for selecting PHS tolerant varieties in cereal breeding programs. Plants of known PHS tolerant and PHS susceptible varieties were grown under controlled conditions from flowering until harvest ripeness. During that period, kernels were regularly harvested for RNA extraction and cDNA synthesis. Calibrated and normalized relative Vp1 expression levels were obtained in an RT-qPCR assay. During kernel development, Vp1 expression levels generally showed a typical peak during the soft dough stage, after which they decreased and remained low until harvest maturity. Differences in Vp1 expression levels could be observed between the PHS susceptible and PHS tolerant varieties of wheat, with the PHS tolerant variety showing higher levels of relative Vp1 expression compared to the PHS susceptible variety. In triticale, however, this difference was only seen once and could not be confirmed in further experiments. It seems that the Vp1 gene in triticale behaves in a similar way as in rye, in which no specific trends could be observed.  相似文献   

Comment on "Nonreciprocal light propagation in a silicon photonic circuit"     

Fan S  Baets R  Petrov A  Yu Z  Joannopoulos JD  Freude W  Melloni A  Popović M  Vanwolleghem M  Jalas D  Eich M  Krause M  Renner H  Brinkmeyer E  Doerr CR 《Science (New York, N.Y.)》2012,335(6064):38; author reply 38

We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function.  相似文献   

Innovations in the diagnosis of infectious agents of veterinary importance--a seven-league boots fairy tale?     

Harder TC  Höper D  Beer M 《Berliner und Münchener tier?rztliche Wochenschrift》2012,125(1-2):14-20

The development of infectiological diagnostic methodology is characterized by saltatoric, revolutionary leaps. Improved sensitivity and specificity, reduction of analytical sample volumes, increased sample throughput, reduced test complexity associated with improved user friendliness are hallmarks of such developments. Apart from purely technical amenities some innovations also enable conceptual adaptations of monitoring strategies. These include the use of diagnostic assays on-site, e. g. in the stable or in the practice. Selecting the assay which is most "fit-for-purpose" among the plethora of sometimes loudly advertised new technology may be difficult even for the well trained and experienced diagnostician. Standardized licensing procedures for infectiological diagnostic kits may be required to guarantee minimal norms of diagnostic quality. At the same time availability of a diversity of diagnostic kits is needed to broaden the base of diagnostic reliability. New infectiological diagnostic innovations will only be useful if the (expanded) results are transposable to the improved practical care of companion animals and farm animal holdings. In addition, the judgment of results, e. g. for epidemiological plausibility, remains a very important issue even when the test results have been produced by novel high technology diagnostics.  相似文献   

Spatio-temporal epidemiology of highly pathogenic avian influenza (H5N1) outbreaks in Nigeria, 2006-2008     

Ekong PS  Ducheyne E  Carpenter TE  Owolodun OA  Oladokun AT  Lombin LH  Berkvens D 《Preventive veterinary medicine》2012,103(2-3):170-177

  相似文献   

Ecological benefits provided by alley cropping systems for production of woody biomass in the temperate region: a review     

Penka Tsonkova  Christian B?hm  Ansgar Quinkenstein  Dirk Freese 《Agroforestry Systems》2012,85(1):133-152

In temperate Europe alley cropping systems which integrate strips of short rotation coppices into conventional agricultural fields (ACS) are receiving increasing attention. These systems can be used for crops and woody biomass production at the same time, enabling farmers to diversify the provision of market goods. Adding trees into the agricultural land creates various additional benefits for the farmer and society, also known as ecosystem services. However, tree-crop interactions in the temperate region have not been adequately substantiated which is identified as a drawback to the practical implementation of such systems. In order to bridge this gap, the current paper aims to present a comprehensive overview of selected ecosystem services provided by agroforestry with focus on ACS in the temperate region. The literature indicates that compared with conventional agriculture ACS have the potential to increase carbon sequestration, improve soil fertility and generally optimize the utilization of resources. Furthermore, due to their structural flexibility, ACS may help to regulate water quality, enhance biodiversity, and increase the overall productivity. ACS are shown as suitable land use systems especially for marginal sites. Based on the available data collected, we conclude that ACS are advantageous compared to conventional agriculture in many aspects, and therefore suggest that they should be implemented at a larger scale in temperate regions.  相似文献   

Prevalence of the causative agents of equine piroplasmosis in the South West of The Netherlands and the identification of two autochthonous clinical Theileria equi infections     

Butler CM  Sloet van Oldruitenborgh-Oosterbaan MM  Stout TA  van der Kolk JH  Wollenberg Lv  Nielen M  Jongejan F  Werners AH  Houwers DJ 《Veterinary journal (London, England : 1997)》2012,193(2):381-385

Equine piroplasmosis (EP) has not been considered indigenous in The Netherlands. However, following the detection of an apparently indigenous subclinical Babesia caballi infection in a horse on Schouwen-Duiveland (an island in the Zeeland Province), a survey was undertaken between May and September 2010 to assess the prevalence of the causative agents of EP in the South-West of The Netherlands. Blood samples from 300 randomly selected horses were tested for specific antibodies against Theileria equi and B. caballi using an indirect fluorescence antibody test (IFAT), and for parasite DNA using a specific polymerase chain reaction combined with reverse line blotting (PCR-RLB). Twelve of the horses (4%) were seropositive for EP. Of these, nine (75%) were positive (titre?1:160) for B. caballi alone and three (25%) were also positive for T. equi. PCR-RLB detected T. equi DNA in five horses (1.6%), two of which were seronegative. Four (1.3%) of the positive horses (three positive for T. equi and one for both B. caballi and T. equi) were considered truly indigenous. During the study, two indigenous ponies from a farm situated outside the sampling area were diagnosed with acute clinical piroplasmosis characterized by severe anaemia and pyrexia. Blood smears showed T. equi - like inclusions in red blood cells, and T. equi infection was confirmed in both ponies by PCR-RLB. The initial subclinical B. caballi infection, the survey results and the two acute clinical EP cases confirmed the autochthonous transmission of B. caballi and T. equi infections in The Netherlands.  相似文献   

Wind effects on trees     

Dirk Schindler  Jürgen Bauhus  Helmut Mayer 《European Journal of Forest Research》2012,131(1):159-163

  相似文献   

Small lateral air pressure gradients generated by a large chamber system have a strong effect on CO2 transport in soil     

Laurin Osterholt  Martin Maier  Dirk Schindler 《European Journal of Soil Science》2023,74(4):e13405

Gas transport in soils is usually assumed to be purely diffusive, although several studies have shown that non-diffusive processes can significantly enhance soil gas transport. These processes include barometric air pressure changes, wind-induced pressure pumping and static air pressure fields generated by wind interacting with obstacles. The associated pressure gradients in the soil can cause advective gas fluxes that are much larger than diffusive fluxes. However, the contributions of the respective transport processes are difficult to separate. We developed a large chamber system to simulate pressure fields and investigate their influence on soil gas transport. The chamber consists of four subspaces in which pressure is regulated by fans that blow air in or out of the chamber. With this setup, we conducted experiments with oscillating and static pressure fields. CO₂ concentrations were measured along two soil profiles beneath the chamber. We found a significant relationship between static lateral pressure gradients and the change in the CO₂ profiles (R² = 0.53; p-value <2e-16). Even small pressure gradients between −1 and 1 Pa relative to ambient pressure resulted in an increase or decrease in CO₂ concentrations of 8% on average in the upper soil, indicating advective flow of air in the pore space. Positive pressure gradients resulted in decreasing, negative pressure gradients in increasing CO₂ concentrations. The concentration changes were probably caused by an advective flow field in the soil beneath the chamber generated by the pressure gradients. No effect of oscillating pressure fields was observed in this study. The results indicate that static lateral pressure gradients have a substantial impact on soil gas transport and therefore are an important driver of gas exchange between soil and atmosphere. Lateral pressure gradients in a comparable range can be induced under windy conditions when wind interacts with terrain features. They can also be caused by chambers used for flux measurements at high wind speed or by fans used for head-space mixing within the chambers, which yields biased flux estimates.  相似文献