RESPONS FISIOLOGIS DAN ANATOMI AKAR TANAMAN BAYAM (Amaranthus tricolor L.) TERHADAP CEKAMAN NaCl

Tujuan dari penelitian ini untuk mengetahui pengaruh cekaman NaCl terhadap pertumbuhan dan anatomi akar tanaman bayam serta mengetahui konsentrasi NaCl yang dapat menghambat pertumbuhan tanaman bayam. Penelitian ini digunakan perlakuan NaCl sebanyak 0, 200, 400, 600 dan 800 mM pada tanaman bayam (Amaranthus tricolor L.), Media tanam berupa campuran tanah dan pupuk kandang dan alkohol, safranin, aseton. Alat yang digunakan adalah med line, cawan poerslen, spektrofotometer dan mikroskop. Parameter yang diukur meliputi tinggi tanaman, jumlah daun, warna daun, panjang akar, jumlah akar, berat basah, berat kering, kadar klorofil, tebal epidermis akar, tebal korteks akar dan diameter stele akar. Data dianalisis dengan uji ANOVA dilanjutkan dengan DMRT taraf kepercayaan 95% menggunakan program SPSS 15. Hasil yang diperoleh menunjukkan penambahan NaCl menyebabkan penurunan pertumbuhan tanaman bayam meliputi tinggi tanaman, jumlah daun, kadar klorofil, rasio tajuk dibanding akar dan menurunkan diameter stele akar. Pertumbuhan tanaman menurun seiring peningkatan konsentrasi NaCl karena NaCl menyebabkan cekaman osmotik yang menghambat penyerapan air dan unsur hara yang diperlukan tanaman untuk proses metabolisme.PHYSIOLOGICAL RESPONSE AND ANATOMY OF ROOTY PLANT [ Amaranthus tricolor L.] AGAINST NaClThe study was aimed at determining the effect of NaCl stress on the growth and anatomy of spinach roots and the concentration of NaCl which can inhibit the growth of spinach plants. This study used 0, 200, 400, 600 and 800 mM NaCl treatments on spinach (Amaranthus tricolor L.), planting media in the form of a mixture of soil and manure and alcohol, safranin, acetone. Med line, poerslen cup, spectrophotometer, and microscope were used in this study. The parameters measured plant height, number of leaves, leaf color, root length, number of roots, wet weight, dry weight, chlorophyll content, root epidermis thickness, root cortex thickness, and root stele diameter. The collected data then were analyzed by ANOVA test followed by DMRT 95% confidence level using the SPSS 15 program. The results obtained showed that the addition of NaCl caused a decrease in spinach plant growth including plant height, the number of leaves, chlorophyll content, the ratio of the crown to root and decreased diameter of root stele. Plant growth decreases with increasing NaCl concentration since NaCl causes osmotic stress. This stress inhibits the absorption of water and nutrients needed by plants for metabolic processes.

Comparing Kinetics of Xylem Ion Loading and Its Regulation in Halophytes and Glycophytes

Although control of xylem ion loading is essential to confer salinity stress tolerance, specific details behind this process remain elusive. In this work, we compared the kinetics of xylem Na+ and K+ loading between two halophytes (Atriplex lentiformis and quinoa) and two glycophyte (pea and beans) species, to understand the mechanistic basis of the above process. Halophyte plants had high initial amounts of Na+ in the leaf, even when grown in the absence of the salt stress. This was matched by 7-fold higher xylem sap Na+ concentration compared with glycophyte plants. Upon salinity exposure, the xylem sap Na+ concentration increased rapidly but transiently in halophytes, while in glycophytes this increase was much delayed. Electrophysiological experiments using the microelectrode ion flux measuring technique showed that glycophyte plants tend to re-absorb Na+ back into the stele, thus reducing xylem Na+ load at the early stages of salinity exposure. The halophyte plants, however, were capable to release Na+ even in the presence of high Na+ concentrations in the xylem. The presence of hydrogen peroxide (H2O2) [mimicking NaCl stress-induced reactive oxygen species (ROS) accumulation in the root] caused a massive Na+ and Ca2+ uptake into the root stele, while triggering a substantial K+ efflux from the cytosol into apoplast in glycophyte but not halophytes species. The peak in H2O2 production was achieved faster in halophytes (30 min vs 4 h) and was attributed to the increased transcript levels of RbohE. Pharmacological data suggested that non-selective cation channels are unlikely to play a major role in ROS-mediated xylem Na+ loading.

LAZY3 plays a pivotal role in positive root gravitropism in Lotus japonicus

LAZY3, polarly localized to the plasma membrane in root stele cells, is involved in rootward polar auxin transport in roots and required for positive root gravitropism in Lotus japonicus.

The receptor-like kinases BAM1 and BAM2 promote the cell-to-cell movement of miRNA in the root stele to regulate xylem patterning

ABSTRACTXylem patterning in the root is established through the creation of opposing gradients of miRNAs and their targets, enabled by the cell-to-cell spread of the former. The miRNAs involved in xylem patterning, miR165/6, move through plasmodesmata, but how their trafficking is regulated remains elusive. Here, we describe that the receptor-like kinases BAM1/2 are required for the intercellular movement of miR165/6 in the stele and hence proper xylem patterning in the root.

Root Anatomy based on Root Cross-Section Image Analysis with Deep Learning

The aboveground plant efficiency has improved significantly in recent years, and the improvement has led to a steady increase in global food production. The improvement of belowground plant efficiency has the potential to further increase food production. However, the belowground plant roots are harder to study, due to inherent challenges presented by root phenotyping. Several tools for identifying root anatomical features in root cross-section images have been proposed. However, the existing tools are not fully automated and require significant human effort to produce accurate results. To address this limitation, we propose a fully automated approach, called Deep Learning for Root Anatomy (DL-RootAnatomy), for identifying anatomical traits in root cross-section images. Using the Faster Region-based Convolutional Neural Network (Faster R-CNN), the DL-RootAnatomy models detect objects such as root, stele and late metaxylem, and predict rectangular bounding boxes around such objects. Subsequently, the bounding boxes are used to estimate the root diameter, stele diameter, and late metaxylem number and average diameter. Experimental evaluation using standard object detection metrics, such as intersection-over-union and mean average precision, has shown that our models can accurately detect the root, stele and late metaxylem objects. Furthermore, the results have shown that the measurements estimated based on predicted bounding boxes have very small root mean square error when compared with the corresponding ground truth values, suggesting that DL-RootAnatomy can be used to accurately detect anatomical features. Finally, a comparison with existing approaches, which involve some degree of human interaction, has shown that the proposed approach is more accurate than existing approaches on a subset of our data. A webserver for performing root anatomy using our deep learning pre-trained models is available at https://rootanatomy.org, together with a link to a GitHub repository that contains code that can be used to re-train or fine-tune our network with other types of root-cross section images. The labeled images used for training and evaluating our models are also available from the GitHub repository.

Shoot Wilt of Petunia sp. Following Drenching with Exogenous ABA

A new agricultural product containing the physiologically active cis form of abscisic acid (C-ABA) is scheduled to become available for ornamental production in 2012. This plant growth regulator generally prolongs irrigation intervals of ornamental plants. During pre-registration testing, the product greatly reduced whole plant transpiration on a variety of species, extending the time between irrigations whether applied as a drench or a foliar spray. However in some instances, drench application resulted in whole plant wilting of some annual species after one to three days. This occurred most often with certain cultivars of coleus, tomato and petunia. Investigations reported here associate wilting of petunia with low xylem water potential and near complete stomatal closure caused by prevention of water movement into root stele. Evidence is presented implicating that the exogenous C-ABA induced closure of root aquaporins led to shoot wilt.