Comparative studies between diploid and tetraploid Dez Orange [Citrus sinensis (L.) Osb.] under salinity stress

Abstract Due to salt-sensitivity nature of citrus, it is imperative to provide rootstocks and cultivars that are tolerant to saline conditions. In this study, responses of tetraploid (4X) and its corresponding diploid (2X) Dez orange (Citrus sinensis (L.) Osb.) cultivar to different concentrations of NaCl (0, 20, 40 and 60 mM) were investigated using a randomized complete block design with four replications. Plant mineral concentrations, proline accumulation, malondialdehyde (MDA) and H 2 O 2 contents were measured. Results indicated that increasing NaCl concentration significantly reduced leaf N and P contents in both diploid and tetraploid plants but reduction of these nutrients were lower in tetraploids (2.15 to 1.51%, 2.35 to 1.78% in diploid and tetraploid plants respectively, at P≤0.05). Results also showed that the accumulation of Na and Cl was lower in tetraploids. Reduction of K in tetraploid was lower as opposed to diploid plants (1.18 and 0.98% in leaves and, 0.50 and 0.48 in roots at 60 mM NaCl, respectively). Free proline content in the leaves of both plants increased with increasing NaCl level with a more marked increase was observed in tetraploid plants than those in diploids (62.3 and 54.8 µmol/g FW at 60 mM NaCl, respectively). Tetraploid plants contained lower concentration of MDA (37.1 and 44.3 nmol/g FW at 60 mM NaCl, respectively) and H 2 O 2 (58.8 and 62.5 µmol/g FW at 60 mM NaCl, respectively). Results obtained in this study suggested that tetraploid Dez orange exhibited a better adaptation to salinity stress than its corresponding diploid in its seedling stage

DELTA-MRI: Direct deformation Estimation from LongiTudinally Acquired k-space data

Longitudinal MRI is an important diagnostic imaging tool for evaluating the effects of treatment and monitoring disease progression. However, MRI, and particularly longitudinal MRI, is known to be time consuming. To accelerate imaging, compressed sensing (CS) theory has been applied to exploit sparsity, both on single image as on image sequence level. State-of-the-art CS methods however, are generally focused on image reconstruction, and consider analysis (e.g., alignment, change detection) as a post-processing step. In this study, we propose DELTA-MRI, a novel framework to estimate longitudinal image changes {\it directly} from a reference image and subsequently acquired, strongly sub-sampled MRI k-space data. In contrast to state-of-the-art longitudinal CS based imaging, our method avoids the conventional multi-step process of image reconstruction of subsequent images, image alignment, and deformation vector field computation. Instead, the set of follow-up images, along with motion and deformation vector fields that describe their relation to the reference image, are estimated in one go. Experiments show that DELTA-MRI performs significantly better than the state-of-the-art in terms of the normalized reconstruction error.Comment: 5 pages, 4 figures, Submitted to ISBI 202

Assessing five citrus rootstocks for NaCl salinity tolerance using mineral concentrations, proline and relative water contents as indicators

Changes in concentrations of Na, Cl and K, proline and Relative Water Contet (RWC) of five citrus species (Cleopatra mandarin, Carrizo citrange, Tiwanica, Bacraii and Shaker) grown in four NaCl salinity levels (0, 25, 50 and 75 mM NaCl) for the purpose of assessing their magnitude of susceptibility to salinity and estimating the salt tolerance degree were studied. The Na and Cl concentrations increased whilst K concentration in leaves decreased with increasing NaCl concentration in the rootzone. Shaker and Cleopatra mandarin accumulated optimal concentration of the ions in their tissues. Increasing NaCl concentration reduced RWC and increased proline content in plant tissues. Shaker and Cleopatra mandarin rootstocks maintained relatively higher leaf RWC and proline in comparison to other rootstocks. Cleopatra mandarin and Shaker showed to be markedly less affected by salinity up to 50 mM NaCl and could bear the highest salinity levels (75 mM) imposed in this study

Improvement of salinity tolerance of citrus scion using tolerant rootstocks and interstocks

Soil salinity is one of the most serious environmental threats, that extremely restricts crop production. One of the most effective strategies to overcome salinity effects is by growing salt tolerance plant species. Citrus is a commercial fruit crop and grown exclusively in tropical and sub-tropical zones. It is a glycophyte. The objective of this study was to evaluate the responses of citrus to salinity stress and to estimate amelioration of salinity effects by using tolerant rootstocks, diploid and tetraploid interstocks. Salinity tolerance of five citrus rootstocks namely Cleopatra mandarin (Citrus reshni Hort. Ex Tan.), Carrizo citrange [(Citrus sinensis (L.) Osbeck×Ponicrus trifoliate (L.) Raf.], Tiwanica (Citrus taiwanica Tan.& Shimada), Bacraii (Citrus limettioides × Citrus reticulate) and Shaker [(Citrus limettioides × Citrus reticulate)× Citrus reshni] during germination was tested at various NaCl concentrations. Salt stress affected seed germination, emergence spread, percentage of final emergence and percentage of seedlings survival. At germination stage, Cleopatra mandarin exhibited higher salt-tolerance than other species. In the subsequent study, the growth parameters, mineral concentration, physiological and biochemical traits of abovementioned citrus species were studied to estimate the degree of salt tolerance. The results indicated that the lowest Na and Cl concentrations were observed in leaves of Shaker rootstock. Also results obtained showed that Shaker and Cleopatra mandarin rootstocks maintained higher RWC and proline content. To allow the testing of resistant rootstock, a salt sensitive scion cultivar is needed. For this purpose, salt sensitivity assessment of two locally available citrus cultivars,Limau Nipis (Citrus aurantifolia Swingle) and Limau Kesturi (Citrus microcarpa Bunge) were subjected to NaCl salinity. The results demonstrated that cv. Limau Kesturi was more sensitive to salt stress than cv. Limau Nipis. Therefore, cv. Limau Kesturi was used as a salinity susceptible cultivar in combination with citrus rootstocks for further experimentation in determination of suitable rootstock that could induce salt resistance of the scion. Evaluation of the level of salt tolerance of Limau Kesturi plants budded on Cleopatra mandarin and Shaker rootstocks revealed that salt stress decreased leaf N, P, K concentrations and RWC, while Na, Cl,proline, MDA and H2O2 concentrations of budded Limau Kesturi increased on both tested rootstocks. The results suggested that the Shaker exhibited higher tolerance to salt stress than the Cleopatra mandarin and therefore can be used as an appropriate rootstock. Based on the changes in leaf mineral contents and biochemical compositions in response of tetraploid and diploid Dez orange cultivars (Citrus sinensis (L.) Osbeck grown under saline condition, we noticed that tetraploid Dez orange had induced a higher level of salt tolerance in comparison to diploid Dez orange. Use of tetraploid Dez oranges as interstock for Limau Kesturi showed the tetraploid cultivar generate more tolerance plants against NaCl salt stress and the plant was able to keep acceptable concentrations of mineral contents, proline, MDA and H2O2. Overall, evidences recorded from this study proved that among the rootstocks tested,Shaker, and tetraploid interstocked plants are more tolerant to salinity stress and therefore can be introduced as new source of plant materials for salinity tolerance in the citrus industry

Systematic review of reconstruction techniques for accelerated quantitative MRI

The complete list of the papers that were selected in the categorization phase of the review "Systematic review of reconstruction techniques for accelerated quantitative MRI", in combination with the properties that describe them.Other grants: SEP BOF; Grant Number FFB210120, Fonds Wetenschappelijk Onderzoek; Grant Number G084217

ADEPT : Accurate Diffusion Echo-Planar imaging with multi-contrast shoTs

Purpose To introduce a novel imaging and parameter estimation framework for accurate multi-shot diffusion MRI. Theory and Methods We propose a new framework called ADEPT (Accurate Diffusion Echo-Planar imaging with multi-contrast shoTs) that enables fast diffusion MRI by allowing diffusion contrast settings to change between shots in a multi-shot EPI acquisition (i.e., intra-scan modulation). The framework estimates diffusion parameter maps directly from the acquired intra-scan modulated k-space data, while simultaneously accounting for shot-to-shot phase inconsistencies. The performance of the estimation framework is evaluated using Monte Carlo simulation studies and in-vivo experiments and compared to that of reference methods that rely on parallel imaging for shot-to-shot phase correction. Results Simulation and real-data experiments show that ADEPT yields more accurate and more precise estimates of the diffusion metrics in multi-shot EPI data in comparison with the reference methods. Conclusion ADEPT allows fast multi-shot EPI diffusion MRI without significantly degrading the accuracy and precision of the estimated diffusion maps

ADEPT: Accurate Diffusion Echo-Planar imaging with multi-contrast shoTs

Purpose To introduce a novel imaging and parameter estimation framework for accurate multi-shot diffusion MRI. Theory and Methods We propose a new framework called ADEPT (Accurate Diffusion Echo-Planar imaging with multi-contrast shoTs) that enables fast diffusion MRI by allowing diffusion contrast settings to change between shots in a multi-shot EPI acquisition (i.e., intra-scan modulation). The framework estimates diffusion parameter maps directly from the acquired intra-scan modulated k-space data, while simultaneously accounting for shot-to-shot phase inconsistencies. The performance of the estimation framework is evaluated using Monte Carlo simulation studies and in-vivo experiments and compared to that of reference methods that rely on parallel imaging for shot-to-shot phase correction. Results Simulation and real-data experiments show that ADEPT yields more accurate and more precise estimates of the diffusion metrics in multi-shot EPI data in comparison with the reference methods. Conclusion ADEPT allows fast multi-shot EPI diffusion MRI without significantly degrading the accuracy and precision of the estimated diffusion maps