Unlocking the mystery of plants’ survival capability under waterlogging stress

Waterlogging is a major abiotic stress affecting crop plants throughout the world, which hampers crop growth and causes yield loss. There are various types of responses in plants under this stress through the combined operation of different signaling and physiological pathways. However, the correlation between these pathways is extremely limited and not well described in the published papers. Therefore, the complex waterlogging stress-tolerance mechanisms need to be presented most coherently for a comprehensive understanding of this stress. Here, we present sequential responses in plants under oxygen-deprivation stress. The regulation of the N-end rule pathway may be treated as the initial signaling in plants after facing waterlogging stress, but still, it remains a controversial topic. All the pathways under waterlogging stress are directly or indirectly related to glycolysis, tricarboxylic acid (TCA) cycle, programmed cell death (PCD) and removal of reactive oxygen species (ROS). Scientists may consider alanine aminotransferase as the main controlling switch for surviving of plants under waterlogging stress. Triggering the genes responsible for alanine aminotransferase may act as a crucial one to develop a waterlogging tolerant plant due to its ability to control anaerobic fermentation, TCA cycle and efficient utilization of carbons

Antioxidant properties of BJRI vegetable mesta-1 (Hibiscus sabdariffa L.)

Roselle or Mesta (Hibiscus sabdariffa) is one of the plants whose plant parts are used to prepare juices. The Roselle calyx is considered as a good source of antioxidants. But the antioxidant properties of BJRI (Bangladesh Jute Research Institute) released Roselle vegetable variety, BJRI vegetable mesta-1, is not quantified yet. With the objective of making this vegetable more popular among the consumers, an experiment was conducted at the Jute Agriculture Experimental Station, Bangladesh Jute Research Institute, Jagir, Manikganj to find out the antioxidant properties of BJRI vegetable mesta-1. Total four antioxidant components eg., total phenol content, total flavonoid content, proanthocyanidin content, anthocyanin content and three antioxidant activities eg., DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging, (FRAP) ferric ion reducing antioxidant power, H2O2 (hydrogen peroxide), radical scavenging were measured from the calyx sample of BJRI vegetable mesta-1. Among the four antioxidant components, total flavonoid contents (959.53 mg 100 g–1) posses the highest position and anothocyanine contents (0.17 mg 100 g–1) were in the lowest position. FRAP activities were highest among the antioxidant activities of the calyx of our studied vegetable mesta. Our findings represented the quantity of antioxidant contents of the calyx of BJRI vegetable mesta-1 which justify its uses as natural antioxidants. Thus, Roselle calyx may act as an alternative source of antioxidant rich natural herbal tea

Comparative resistance and yield performance of summer mungbean mutants and varieties as affected by MYMV

An experiment was conducted in the research field of the Department of Plant Pathology, Patuakhali Science and Technology University during February to April 2013 to select Mungbean Yellow Mosaic Virus (MYMV) resistant mutant/variety under natural epiphytotic condition. The screening was made on the six mungbean genotypes including three advanced mutant lines, MBM-07, MBM-21, MBM-88 and three varieties Bina mung-5, Bina mung-6, Bina mung-8 as check, to evaluate their reaction to MYMV at flowering and pod maturity stages. It was observed that at the flowering stage of MBM-21, MBM-88, and Bina mung-6 were found resistant with percent disease incidence recorded from 0.5, 1.0, and 0.5 percent respectively. At the maturity stage, no genotype were found to be immune and the disease incidence varied from the lowest 0.5 % in MBM-21 to highest 26 % in MBM-7. The mutant MBM-21 and variety Bina mung-6 were found moderately resistant with disease incidence ranging from 1 to 10 %. Among the less MYMV infected mungbean mutants, MBM-21 gave the highest yield (1569 kg ha-1) and the lowest yield was in MBM-07 (1183kg ha-1). The mutants MBM-21 completed by the short duration of 61.67 days as compared to check Bina mung-6 (67.33 days). Out of six summer screened mungbean mutants and varieties, MBM-21 exhibited highest resistance in both flowering and pod maturity stage. Therefore, MBM-21 might be selected as a resistant variety against MYMV after further trail in different Agro-Ecological Zones (AEZ) of Bangladesh

Differential Response of Sugar Beet to Long-Term Mild to Severe Salinity in a Soil-Pot Culture

Attempts to cultivate sugar beet (Beta vulgaris spp. vulgaris) in the sub-tropical saline soils are ongoing because of its excellent tolerance to salinity. However, the intrinsic adaptive physiology has not been discovered yet in the sub-tropical climatic conditions. In this study, we investigated morpho-physiological attributes, biochemical responses, and yield of sugar beet under a gradient of salinity in the soil-pot culture system to evaluate its adaptive mechanisms. Results exhibited that low and high salinity displayed a differential impact on growth, photosynthesis, and yield. Low to moderate salt stress (75 and 100 mM NaCl) showed no inhibition on growth and photosynthetic attributes. Accordingly, low salinity displayed simulative effect on chlorophyll and antioxidant enzymes activity which contributed to maintaining a balanced H2O2 accumulation and lipid peroxidation. Furthermore, relative water and proline content showed no alteration in low salinity. These factors contributed to improving the yield (tuber weight). On the contrary, 250 mM salinity showed a mostly inhibitory role on growth, photosynthesis, and yield. Collectively, our findings provide insights into the mild-moderate salt adaptation strategy in the soil culture test attributed to increased water content, elevation of photosynthetic pigment, better photosynthesis, and better management of oxidative stress. Therefore, cultivation of sugar beet in moderately saline-affected soils will ensure efficient utilization of lands

Automatic Extraction of Nuclei Centroids of Mouse Embryonic Cells from Fluorescence Microscopy Images

Accurate identification of cell nuclei and their tracking using three dimensional (3D) microscopic images is a demanding task in many biological studies. Manual identification of nuclei centroids from images is an error-prone task, sometimes impossible to accomplish due to low contrast and the presence of noise. Nonetheless, only a few methods are available for 3D bioimaging applications, which sharply contrast with 2D analysis, where many methods already exist. In addition, most methods essentially adopt segmentation for which a reliable solution is still unknown, especially for 3D bio-images having juxtaposed cells. In this work, we propose a new method that can directly extract nuclei centroids from fluorescence microscopy images. This method involves three steps: (i) Pre-processing, (ii) Local enhancement, and (iii) Centroid extraction. The first step includes two variations: first variation (Variant-1) uses the whole 3D pre-processed image, whereas the second one (Variant-2) modifies the preprocessed image to the candidate regions or the candidate hybrid image for further processing. At the second step, a multiscale cube filtering is employed in order to locally enhance the pre-processed image. Centroid extraction in the third step consists of three stages. In Stage-1, we compute a local characteristic ratio at every voxel and extract local maxima regions as candidate centroids using a ratio threshold. Stage-2 processing removes spurious centroids from Stage-1 results by analyzing shapes of intensity profiles from the enhanced image. An iterative procedure based on the nearest neighborhood principle is then proposed to combine if there are fragmented nuclei. Both qualitative and quantitative analyses on a set of 100 images of 3D mouse embryo are performed. Investigations reveal a promising achievement of the technique presented in terms of average sensitivity and precision (i.e., 88.04% and 91.30% for Variant-1; 86.19% and 95.00% for Variant-2), when compared with an existing method (86.06% and 90.11%), originally developed for analyzing C. elegans images

Improved and robust detection of cell nuclei from four dimensional fluorescence images.

Segmentation-free direct methods are quite efficient for automated nuclei extraction from high dimensional images. A few such methods do exist but most of them do not ensure algorithmic robustness to parameter and noise variations. In this research, we propose a method based on multiscale adaptive filtering for efficient and robust detection of nuclei centroids from four dimensional (4D) fluorescence images. A temporal feedback mechanism is employed between the enhancement and the initial detection steps of a typical direct method. We estimate the minimum and maximum nuclei diameters from the previous frame and feed back them as filter lengths for multiscale enhancement of the current frame. A radial intensity-gradient function is optimized at positions of initial centroids to estimate all nuclei diameters. This procedure continues for processing subsequent images in the sequence. Above mechanism thus ensures proper enhancement by automated estimation of major parameters. This brings robustness and safeguards the system against additive noises and effects from wrong parameters. Later, the method and its single-scale variant are simplified for further reduction of parameters. The proposed method is then extended for nuclei volume segmentation. The same optimization technique is applied to final centroid positions of the enhanced image and the estimated diameters are projected onto the binary candidate regions to segment nuclei volumes.Our method is finally integrated with a simple sequential tracking approach to establish nuclear trajectories in the 4D space. Experimental evaluations with five image-sequences (each having 271 3D sequential images) corresponding to five different mouse embryos show promising performances of our methods in terms of nuclear detection, segmentation, and tracking. A detail analysis with a sub-sequence of 101 3D images from an embryo reveals that the proposed method can improve the nuclei detection accuracy by 9% over the previous methods, which used inappropriate large valued parameters. Results also confirm that the proposed method and its variants achieve high detection accuracies (> 98% mean F-measure) irrespective of the large variations of filter parameters and noise levels

Nuclei detection results for the proposed method and its variants.

<p>Number of extracted nuclei by (A) the proposed, (B) Variant-1, (c) Variant-2, and (D) Variant-3 over time. Results include 101 sequential images from a developing embryo containing 8 to 32 cells.</p

Robustness analysis against additive white Gaussian noise.

<p>(blue) SNR levels, (light-blue) ground truth, and the number of estimated nuclei for (red) the proposed, (green) previous-1, (purple) previous-2 against increasing noise spreads, when large initial parameters (, , and ) are selected. Note that the proposed method re-estimates a new set of parameters: , , and using feedback mechanism, while previous methods fail to do. A 3D image having 32 nuclei is considered for analysis.</p

Nuclei tracking results at 8- and 16-cell stages of an embryo.

<p>Nuclear motion tracks in the (A, B, C) 8-cell and (D, E, F) 16-cell stages; Blue and red lines in the 2D projected space (A, D) and 3D space (B, E) indicate the estimated and ground truth nuclear tracks without explicit moving directions; Color gradients in the 3D space (C, F) indicate the directions through which cells move inside the embryo. Blue and red colors indicate the start and end points of the moving cells. Note that twenty two frames (i.e., t1 to t22) at the 8-cell stage and twenty six frames (i.e., t36 to t61) at 16-cell stage are used for track generation. The selected distance threshold () for the correspondence establishment was 25 pixels.</p

Contrast-enhanced 2D slices from our image dataset.

<p>Sample images with time-point and z-slice pairs at (A) (t25, 18), (B) (t34, 35), (C) (t45, 22), (D) (t86, 22), (E) (t91, 24), and (F) (t98, 29). Each image has dimension: 103 103 pixels and has voxel resolution: and µm.</p