Transcriptional Activation of OsDERF1 in OsERF3 and OsAP2-39 Negatively Modulates Ethylene Synthesis and Drought Tolerance in Rice

The phytohormone ethylene is a key signaling molecule that regulates a variety of developmental processes and stress responses in plants. Transcriptional modulation is a pivotal process controlling ethylene synthesis, which further triggers the expression of stress-related genes and plant adaptation to stresses; however, it is unclear how this process is transcriptionally modulated in rice. In the present research, we report the transcriptional regulation of a novel rice ethylene response factor (ERF) in ethylene synthesis and drought tolerance. Through analysis of transcriptional data, one of the drought-responsive ERF genes, OsDERF1, was identified for its activation in response to drought, ethylene and abscisic acid. Transgenic plants overexpressing OsDERF1 (OE) led to reduced tolerance to drought stress in rice at seedling stage, while knockdown of OsDERF1 (RI) expression conferred enhanced tolerance at seedling and tillering stages. This regulation was supported by negative modulation in osmotic adjustment response. To elucidate the molecular basis of drought tolerance, we identified the target genes of OsDERF1 using the Affymetrix GeneChip, including the activation of cluster stress-related negative regulators such as ERF repressors. Biochemical and molecular approaches showed that OsDERF1 at least directly interacted with the GCC box in the promoters of ERF repressors OsERF3 and OsAP2-39. Further investigations showed that OE seedlings had reduced expression (while RI lines showed enhanced expression) of ethylene synthesis genes, thereby resulting in changes in ethylene production. Moreover, overexpression of OsERF3/OsAP2-39 suppressed ethylene synthesis. In addition, application of ACC recovered the drought-sensitive phenotype in the lines overexpressing OsERF3, showing that ethylene production contributed to drought response in rice. Thus our data reveal that a novel ERF transcriptional cascade modulates drought response through controlling the ethylene synthesis, deepening our understanding of the regulation of ERF proteins in ethylene related drought response

Parametric finite element study on slotted rectangular and square HSS tension connections

A parametric finite element analysis study was carried out on slotted rectangular and square hollow structural section (HSS) tension connections without welding at the end of the gusset plate for different weld length ratio, slot orientation, weld size and level of HSS corner strength compared to its flat segment. Finite element models for the parametric study were developed and validated against test results of the connection with the tube slotted. The modified weld length ratio was found to be a better parameter than the modified eccentricity ratio in characterizing the net section efficiency of a slotted HSS tension member when the weld length is short. Improvements to provisions in CSA-S16-01 and ANSI/AISC-360-05 for slotted tubular tension connections were proposed based on results of the study

Non-destructive estimation of rice plant nitrogen status with Crop Circle multispectral active canopy sensor

Crop Circle is an active multispectral canopy sensor developed to support precision crop management. The Crop Circle ACS-470 model is user configurable, with a choice of six wavebands covering blue, green, red, red edge and near infrared spectral regions. The objectives of this study were to determine how well nitrogen (N) status of rice (Oryza sativa L) can be estimated with the Crop Circle ACS-470 active sensor using green, red edge and near infrared (NIR) bands at key growth stages and identify important vegetation indices for estimating rice N status indicators. Six field experiments involving different N rates and two varieties were conducted in Sanjiang Plain in Heilongjiang Province, China during 2011 and 2012. Crop sensor data and plant samples were also collected from five farmers' fields to further evaluate the sensor and selected vegetation indices. The results of the study indicated that among 43 different vegetation indices evaluated, modified chlorophyll absorption reflectance index 1 (MCARI1) had consistent correlations with rice aboveground biomass (R-2=0.79) and plant N uptake (R-2=0.83) across growth stages. Four red edge-based indices, red edge soil adjusted vegetation index (RESAVI), modified RESAVI (MRESAVI), red edge difference vegetation index (REDVI) and red edge re-normalized difference vegetation index (RERDVI), performed equally well for estimating N nutrition index (NNI) across growth stages (R-2=0.76). For rice plant N concentration, the highest R-2 was 0.33, and none of the indices performed satisfactorily with validation using farmers' field data. We conclude that the Crop Circle ACS-470 active canopy sensor allows users the flexibility to select suitable bands and calculate different vegetation indices and has a great potential for in-season non-destructive estimation of rice biomass, plant N uptake and NNI. (C) 2013 Elsevier B.V. All rights reserved

Demonstration of the detection of buckling effects in steel pipelines and beams by the distributed Brillouin sensor

We conducted the strain measurements to monitor steel pipe buckling for the first time using distributed Brillouin sensor system. Two specimens (steel pipeline and beam) were prepared by locally thinning the inner wall to provoke buckling. Fibre was laid along the external walls of the specimens. Strain gauges were glued in thinned wall area. An axial load was applied to the specimens and increased while compressive strain was measured by both Brillouin sensor and the strain gauges. The Brillouin sensor measurements showed the convolution of the all the strain distribution within the spatial resolution, the fitting Brillouin peak corresponds to the average strain over the spatial resolution, hence its reading can be smaller than the strain gauge reading depending on the location. With the Brillouin sensors, we observed compression in the whole specimens while elongation was detected in the neighbourhood of the thinned wall at onset of the buckling for the first time. The buckling was identified and localized with the Brillouin sensor measurement