Publications

2019
Ben-Zeev, S. ; Bimro, J. ; Barak, V. ; Saranga, Y. . Phenotypic Diversity And Heritability In Eragrostis Tef Under Irrigated Mediterranean Conditions. Israel Journal of Plant Sciences 2019, 65, 222-231. Publisher's VersionAbstract
Tef (Eragrostis tef (Zucc.) Trotter) is a C4 annual cereal, common in Ethiopia, where it was presumably domesticated. Worldwide interest in tef cultivation and consumption has considerably increased in the last few decades because it is a gluten-free grain with high nutritional value. Here we report on the genetic diversity and heritability in a tef germplasm collection characterized in Israel. A total of 408 accessions of tef held in the Israel Gene Bank were grown in 2015 under common garden (screen-house) conditions for propagation and initial phenotyping. A diversity panel, consisting of 273 accessions representing the entire collection's range of phenotypic diversity, was assembled and evaluated in small field plots in 2016. Further evaluation was conducted in 2017, in single-plant field plots (to eliminate admixtures). A representative plant (plot) was selected from each accession grown in 2017 and its single seed descent progenies where grown in 2018 in single-plant plots. The collection exhibited a wide diversity for each of the measured phenotypic traits, across all four environments. High grain yield was associated in most cases with early flowering time, whereas higher biomass was associated with late flowering. Heritability estimates, calculated based on the 2017, 2018 data, varied between 0.11 for plant biomass and 0.75 for 1000 grain weight. This study shows that tef can successfully grow and produce under irrigated Mediterranean conditions. The wide diversity available in our germplasm collection can provide the foundations for breeding new tef cultivars that are better adapted to these conditions. © Koninklijke Brill NV, Leiden, 2018.
Fatiukha, A. ; Klymiuk, V. ; Peleg, Z. ; Saranga, Y. ; Cakmak, I. ; Krugman, T. ; Korol, A. B. ; Fahima, T. . Variation In Phosphorus And Sulfur Content Shapes The Genetic Architecture And Phenotypic Associations Within The Wheat Grain Ionome. Plant Journal 2019. Publisher's VersionAbstract
Dissection of the genetic basis of wheat ionome is crucial for understanding the physiological and biochemical processes underlying mineral accumulation in seeds, as well as for efficient crop breeding. Most of the elements essential for plants are metals stored in seeds as chelate complexes with phytic acid or sulfur-containing compounds. We assume that the involvement of phosphorus and sulfur in metal chelation is the reason for strong phenotypic correlations within ionome. Adjustment of element concentrations for the effect of variation in phosphorus and sulfur seed content resulted in drastic change of phenotypic correlations between the elements. The genetic architecture of wheat grain ionome was characterized by quantitative trait loci (QTL) analysis using a cross between durum and wild emmer wheat. QTL analysis of the adjusted traits and two-trait analysis of the initial traits paired with either P or S considerably improved QTL detection power and accuracy, resulting in the identification of 105 QTLs and 617 QTL effects for 11 elements. Candidate gene search revealed some potential functional associations between QTLs and corresponding genes within their intervals. Thus, we have shown that accounting for variation in P and S is crucial for understanding of the physiological and genetic regulation of mineral composition of wheat grain ionome and can be implemented for other plants. © 2019 The Authors The Plant Journal © 2019 John Wiley & Sons Ltd
Dadon, A. ; Mandelmilch, M. ; Ben-Dor, E. ; Sheffer, E. . Sequential Pca-Based Classification Of Mediterranean Forest Plants Using Airborne Hyperspectral Remote Sensing. Remote Sensing 2019, 11. Publisher's VersionAbstract
In recent years, hyperspectral remote sensing (HRS) has become common practice for remote analyses of the physiognomy and composition of forests. Supervised classification is often used for this purpose, but demands intensive sampling and analyses, whereas unsupervised classification often requires information retrieval out of the large HRS datasets, thereby not realizing the full potential of the technology. An improved principal component analysis-based classification (PCABC) scheme is presented and intended to provide accurate and sequential image-based unsupervised classification of Mediterranean forest species. In this study, unsupervised classification and reduction of data size are performed simultaneously by applying binary sequential thresholding to principal components, each time on a spatially reduced subscene that includes the entire spectral range. The methodology was tested on HRS data acquired by the airborne AisaFENIX HRS sensor over a Mediterranean forest in Mount Horshan, Israel. A comprehensive field-validation survey was performed, sampling 257 randomly selected individual plants. The PCABC provided highly improved results compared to the traditional unsupervised classification methodologies, reaching an overall accuracy of 91%. The presented approach may contribute to improved monitoring, management, and conservation of Mediterranean and similar forests. © 2019 by the authors.
Dovrat, G. ; Sheffer, E. . Symbiotic Dinitrogen Fixation Is Seasonal And Strongly Regulated In Water-Limited Environments. New Phytologist 2019, 221, 1866-1877. Publisher's VersionAbstract
Plants, especially perennials, growing in drylands and seasonally dry ecosystems are uniquely adapted to dry conditions. Legume shrubs and trees, capable of symbiotic dinitrogen (N 2 ) fixation, often dominate in drylands. However, the strategies that allow symbiotic fixation in these ecosystems, and their influence on the nitrogen cycle, are largely unresolved. We evaluated the climatic, biogeochemical and ontogenetic factors influencing nitrogen fixation in an abundant Mediterranean legume shrub, Calicotome villosa. We measured nodulation, fixation rate, nitrogen allocation and soil biogeochemistry in three field sites over a full year. A controlled experiment evaluated differences in plant regulation of fixation as a function of soil nutrient availability and seedling and adult developmental stages. We found a strong seasonal pattern, shifting between high fixation rates during the rainy season at flowering and seed-set times to almost none in the rainless season. Under controlled conditions, plants downregulated fixation in response to soil nitrogen availability, but this response was stronger in seedlings than in adult shrubs. Finally, we did not find elevated soil nitrogen under N 2 -fixing shrubs. We conclude that seasonal nitrogen fixation, regulation of fixation, and nitrogen conservation are key adaptations influencing the dominance of dryland legumes in the community, with broader consequences on the ecosystem nitrogen cycle. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust
Kam, D. ; Layani, M. ; BarkaiMinerbi, S. ; Orbaum, D. ; Abrahami BenHarush, S. ; Shoseyov, O. ; Magdassi, S. . Additive Manufacturing Of 3D Structures Composed Of Wood Materials. Advanced Materials Technologies 2019, 4. Publisher's VersionAbstract
3D objects composed of 100% wood components are 3D printed utilizing wood flour microparticles dispersed in a matrix composed of cellulose nanocrystals and xyloglucan. In the printed object, a wood waste product is “glued” with extracted wood products, to be a substitute for pristine wood. 3D printing is used to maximize conversion of low value materials into final products that exhibit visual, textural, and physical properties of natural timber. Several 3D printing technologies are applied to achieve a wide range of densities, mechanical properties, colors, and morphologies as well as high thermal insulation. Furthermore, the 3D printing process enables predesigning of fiber layout in the printed wood, which enables control of shrinkage orientation. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Seeherman, H. J. ; Berasi, S. P. ; Brown, C. T. ; Martinez, R. X. ; Sean Juo, Z. ; Jelinsky, S. ; Cain, M. J. ; Grode, J. ; Tumelty, K. E. ; Bohner, M. ; et al. A Bmp/Activin A Chimera Is Superior To Native Bmps And Induces Bone Repair In Nonhuman Primates When Delivered In A Composite Matrix. Science Translational Medicine 2019, 11. Publisher's VersionAbstract
Bone morphogenetic protein (BMP)/carriers approved for orthopedic procedures achieve efficacy superior or equivalent to autograft bone. However, required supraphysiological BMP concentrations have been associated with potential local and systemic adverse events. Suboptimal BMP/receptor binding and rapid BMP release from approved carriers may contribute to these outcomes. To address these issues and improve efficacy, we engineered chimeras with increased receptor binding by substituting BMP-6 and activin A receptor binding domains into BMP-2 and optimized a carrier for chimera retention and tissue ingrowth. BV-265, a BMP-2/BMP-6/activin A chimera, demonstrated increased binding affinity to BMP receptors, including activin-like kinase-2 (ALK2) critical for bone formation in people. BV-265 increased BMP intracellular signaling, osteogenic activity, and expression of bone-related genes in murine and human cells to a greater extent than BMP-2 and was not inhibited by BMP antagonist noggin or gremlin. BV-265 induced larger ectopic bone nodules in rats compared to BMP-2 and was superior to BMP-2, BMP-2/6, and other chimeras in nonhuman primate bone repair models. A composite matrix (CM) containing calcium-deficient hydroxyapatite granules suspended in a macroporous, fenestrated, polymer mesh–reinforced recombinant human type I collagen matrix demonstrated improved BV-265 retention, minimal inflammation, and enhanced handling. BV-265/CM was efficacious in nonhuman primate bone repair models at concentrations ranging from 1 / 10 to 1 / 30 of the BMP-2/absorbable collagen sponge (ACS) concentration approved for clinical use. Initial toxicology studies were negative. These results support evaluations of BV-265/CM as an alternative to BMP-2/ACS in clinical trials for orthopedic conditions requiring augmented healing. Copyright © 2019 The Authors.
Morantes, D. ; Muñoz, E. ; Kam, D. ; Shoseyov, O. . Highly Charged Cellulose Nanocrystals Applied As A Water Treatment Flocculant. Nanomaterials 2019, 9. Publisher's VersionAbstract
Various cellulosic materials have replaced petroleum-derived polymers, offering natural and sustainable alternatives. Among them, cellulose nanocrystals (CNC) feature an easily modifiable surface, enabling the exploration of a wide spectrum of applications. In this work, the quaternary agent 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) was used as a cationic graft on CNCs, to form a novel water treatment flocculant. The resulting material was chemically and structurally characterized by the determination of Zeta potential; degree of substitution by elemental analysis; hydrodynamic size by dynamic light scattering (DLS) and infrared spectroscopy with Fourier Transform Infrared (FT-IR); and X-ray diffraction (XRD). The flocculation capacity of cationic cellulose nanocrystals (CNC-EPTMAC) was evaluated in a jar test filled with an 0.25 wt.% silica (SiO2) suspension. CNC-EPTMAC proved to be an effective water treatment flocculant, reducing turbidity by up to 99.7% at a concentration of only 2 ppm. This work demonstrates a natural and environmentally sustainable alternative to homologous commercial flocculants. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.
Mikael, P. E. ; Udangawa, R. ; Sorci, M. ; Cress, B. ; Shtein, Z. ; Belfort, G. ; Shoseyov, O. ; Dordick, J. S. ; Linhardt, R. J. . Production And Characterization Of Recombinant Collagen-Binding Resilin Nanocomposite For Regenerative Medicine Applications. Regenerative Engineering and Translational Medicine 2019, 5, 362-372. Publisher's VersionAbstract
Abstract: Development of mechanically stable and multifunctional biomaterials for sensing, repair, and regeneration applications is of great importance. Herein, we investigate the potential of recombinant resilin-like (Res) nanocomposite elastomer as a template biomaterial for regenerative devices such as adhesive bandages or films, electrospun fibers, screws, sutures, and drug delivery vehicles. Exon I (Rec1) from the native resilin gene of Drosophila (CG15920) was fused with collagen-binding domain (ColBD) from Clostridium histolyticum and expressed in Komagataella pastoris (formerly Pichia pastoris). The 100% binding of Resilin-ColBD (Res-ColBD) to collagen I was shown at a 1:1 ratio by mass. Atomic force microscopy results in force mode show a bimodal profile for the ColBD-binding interactions. Moreover, based on the force-volume map, Res-ColBD adhesion to collagen was statistically significantly higher than resilin without ColBD. Lay Summary: Designing advanced biomaterials that will not only withstand the repetitive mechanical loading and flexibility of tissues but also retain biochemical and biophysical interactions remains challenging. The combination of physical, biological, and chemical cues is vital for disease regulation, healing, and ultimately complete regeneration of functional human tissues. Resilin is a super elastic and highly resilient natural protein with good biocompatibility but lacks specific biological and chemical cues. Therefore, resilin decorated with collagen I–binding domain is proposed as a functional nanocomposite template biomaterial. Collagen I is an ideal binding target, as it is the most abundant structural protein found in human body including scars that affect unwanted adhesion. Future Work: Musculoskeletal-related injuries and disorders are the second largest cause of disabilities worldwide. Significant pain, neurological discomfort, limited mobility, and substantial financial burden are associated with these disorders. Thus, biocompatible materials comprised of resilin with collagen-binding domain, such as films adhesive bandages (films, fiber matts, or hydrogels), sutures, screws and rods, three-dimensional scaffolds, and delivery vehicles, will be designed and evaluated for multiple musculoskeletal-related regeneration applications. © 2019, The Regenerative Engineering Society.
Skaliter, O. ; Ravid, J. ; Shklarman, E. ; Ketrarou, N. ; Shpayer, N. ; Ben Ari, J. ; Dvir, G. ; Farhi, M. ; Yue, Y. ; Vainstein, A. . Ectopic Expression Of Pap1 Leads To Anthocyanin Accumulation And Novel Floral Color In Genetically Engineered Goldenrod (Solidago Canadensis L.). Frontiers in Plant Science 2019, 10. Publisher's VersionAbstract
Floral pigmentation is of major importance to the ornamental industry, which is constantly searching for cultivars with novel colors. Goldenrod (Solidago canadensis) has monochromatic yellow carotenoid-containing flowers that cannot be modified using classical breeding approaches due to a limited gene pool. To generate Solidago with novel colors through metabolic engineering, we first developed a procedure for its regeneration and transformation. Applicability of different cytokinins for adventitious regeneration was examined in the commercial cv. Tara, with zeatin yielding higher efficiency than 6-benzylaminopurine or thidiazuron. A comparison of regeneration of commercial cvs. Tara, Golden Glory and Ivory Glory revealed Tara to be the most potent, with an efficiency of 86% (number of shoots per 100 leaf explants). Agrobacterium-based transformation efficiency was highest for cv. Golden Glory (5 independent transgenic shoots per 100 explants) based on kanamycin selection and the GUS reporter gene. In an attempt to promote anthocyanin biosynthesis, we generated transgenic Solidago expressing snapdragon (Antirrhinum majus) Rosea1 and Delila, as well as Arabidopsis thaliana PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) transcription factors. Transgenic cv. Golden Glory expressing cauliflower mosaic virus 35S-driven PAP1 generated red flowers that accumulated delphinidin and its methylated derivatives, as compared to control yellow flowers in the GUS-expressing plants. The protocol described here allows efficient engineering of Solidago for novel coloration and improved agricultural traits. © Copyright © 2019 Skaliter, Ravid, Shklarman, Ketrarou, Shpayer, Ben Ari, Dvir, Farhi, Yue and Vainstein.
Cárdenas, P. D. ; Sonawane, P. D. ; Heinig, U. ; Jozwiak, A. ; Panda, S. ; Abebie, B. ; Kazachkova, Y. ; Pliner, M. ; Unger, T. ; Wolf, D. ; et al. Pathways To Defense Metabolites And Evading Fruit Bitterness In Genus Solanum Evolved Through 2-Oxoglutarate-Dependent Dioxygenases. Nature Communications 2019, 10. Publisher's VersionAbstract
The genus Solanum comprises three food crops (potato, tomato, and eggplant), which are consumed on daily basis worldwide and also producers of notorious anti-nutritional steroidal glycoalkaloids (SGAs). Hydroxylated SGAs (i.e. leptinines) serve as precursors for leptines that act as defenses against Colorado Potato Beetle (Leptinotarsa decemlineata Say), an important pest of potato worldwide. However, SGA hydroxylating enzymes remain unknown. Here, we discover that 2-OXOGLUTARATE-DEPENDENT-DIOXYGENASE (2-ODD) enzymes catalyze SGA-hydroxylation across various Solanum species. In contrast to cultivated potato, Solanum chacoense, a widespread wild potato species, has evolved a 2-ODD enzyme leading to the formation of leptinines. Furthermore, we find a related 2-ODD in tomato that catalyzes the hydroxylation of the bitter α-tomatine to hydroxytomatine, the first committed step in the chemical shift towards downstream ripening-associated non-bitter SGAs (e.g. esculeoside A). This 2-ODD enzyme prevents bitterness in ripe tomato fruit consumed today which otherwise would remain unpleasant in taste and more toxic. © 2019, The Author(s).
Brog, Y. M. ; Osorio, S. ; Yichie, Y. ; Alseekh, S. ; Bensal, E. ; Kochevenko, A. ; Zamir, D. ; Fernie, A. R. . A Solanum Neorickii Introgression Population Providing A Powerful Complement To The Extensively Characterized Solanum Pennellii Population. Plant Journal 2019, 97, 391-403. Publisher's VersionAbstract
We present a complementary resource for trait fine-mapping in tomato to those based on the intra-specific cross between cultivated tomato and the wild tomato species Solanum pennellii, which have been extensively used for quantitative genetics in tomato over the last 20 years. The current population of backcross inbred lines (BILs) is composed of 107 lines derived after three backcrosses of progeny of the wild species Solanum neorickii (LA2133) and cultivated tomato (cultivar TA209) and is freely available to the scientific community. These S. neorickii BILs were genotyped using the 10K SolCAP single nucleotide polymorphism chip, and 3111 polymorphic markers were used to map recombination break points relative to the physical map of Solanum lycopersicum. The BILs harbor on average 4.3 introgressions per line, with a mean introgression length of 34.7 Mbp, allowing partitioning of the genome into 340 bins and thereby facilitating rapid trait mapping. We demonstrate the power of using this resource in comparison with archival data from the S. pennellii resources by carrying out metabolic quantitative trait locus analysis following gas chromatography–mass spectrometry on fruits harvested from the S. neorickii BILs. The metabolic candidate genes phenylalanine ammonia-lyase and cystathionine gamma-lyase were then tested and validated in F 2 populations and via agroinfiltration-based overexpression in order to exemplify the fidelity of this method in identifying the genes that drive tomato metabolic phenotypes. © 2018 The Authors. The Plant Journal © 2018 John Wiley & Sons Ltd and Society for Experimental Biology.
Cohen, I. ; Netzer, Y. ; Sthein, I. ; Gilichinsky, M. ; Tel-Or, E. . Plant Growth Regulators Improve Drought Tolerance, Reduce Growth And Evapotranspiration In Deficit Irrigated Zoysia Japonica Under Field Conditions. Plant Growth Regulation 2019. Publisher's VersionAbstract
As water becomes a limited and costly resource, water conservation practices in turf grass management will become a necessity. Deficit irrigation (DI) is a common agricultural practice that enables reduction of water expense with minor yield loss. Plant growth regulators (PGRs) restrict plant growth and consequently affect evapotranspiration (ET) rate, soil water depletion and plant tolerance to drought. Our studies evaluated the physiological effects of the PGRs paclobutrazol (Pac) and uniconazole (Uni) in the warm weather turf grass Zoysia japonica under DI in field conditions. Our studies demonstrated that Pac and Uni reduced plant ET rate in greenhouse and field experiments. Uni, was more potent at a low concentration (25 mg L −1 ) than Pac, with greater effect on reducing ET rates, plant vertical growth and biomass accumulation while enhancing tissue chlorophyll content. Under field conditions, both Pac and Uni lowered ET and clipping biomass and raised chlorophyll levels at DI. Additionally, results suggested that Uni increased leaf concentration of abscisic acid (ABA). We conclude that PGR application to the Zoysia turf grass simultaneously improved the clipping management and lowered turf grass water requirement, while maintaining high leaf appearance under deficit irrigation conditions. © 2019, Springer Nature B.V.
Zait, Y. ; Shtein, I. ; Schwartz, A. . Long-Term Acclimation To Drought, Salinity And Temperature In The Thermophilic Tree Ziziphus Spina-Christi: Revealing Different Tradeoffs Between Mesophyll And Stomatal Conductance. Tree Physiology 2019, 39, 701-716. Publisher's VersionAbstract
Photosynthesis is limited by three main factors: stomatal conductance (gs), mesophyll conductance (gm) and maximum capacity for Rubisco carboxylation (Vcmax). It is unclear how limiting factors vary under stress, particularly during long-term stress acclimation. In this work, we compared for the first time photosynthesis limitation resulting from long-term acclimation to three major abiotic stresses: drought, salinity and temperature. We used saplings of Ziziphus spina-christi, a thermophilic and drought-tolerant tree, which recently became more abundant in the Mediterranean, presumably due to increased winter temperatures. Stress acclimation was investigated by measuring growth, gas exchange, chlorophyll fluorescence and leaf structure. For each stress, photosynthesis-limiting factors were compared. We developed an integrative stress index that allowed us to precisely define stress level, enabling a comparison between stress types. Photosynthesis under all stresses was limited mostly by gs and gm (80–90%); whereas biochemistry (Vcmax) made a minor contribution (10–20%). The relative contribution of gs and gm on photosynthetic limitation was influenced by stress type. During acclimation to drought or salinity, photosynthesis was limited by a decline in gs, while intolerance to low temperatures was driven by decline in gm. In all the stresses, gm decreased only under progressive reduction in leaf physiological functionality and was associated with low turgor under drought, an increase in leaf Na+ under salinity and low leaf hydraulic conductance (Kleaf) at low temperatures. Mesophyll structure (mesophyll surface area exposed to the intercellular air spaces, leaf thickness, % intercellular air spaces) did not explain gm acclimation to stress. Current work gives methodology for stress studies, and defines the main factors underlying the plant response to climate change. The ability to minimize mesophyll-imposed limitations on photosynthesis was found as a strong indicator of progressive stress tolerance. Moreover, the results demonstrate how warming climate benefits the photosynthetic function in thermophilic species, such as Ziziphus spina-christi. © The Author(s) 2018.
Maseyk, K. ; Lin, T. ; Cochavi, A. ; Schwartz, A. ; Yakir, D. ; Tissue, D. . Quantification Of Leaf-Scale Light Energy Allocation And Photoprotection Processes In A Mediterranean Pine Forest Under Extensive Seasonal Drought. Tree Physiology 2019, 39, 1767-1782. Publisher's VersionAbstract
Photoprotection strategies in a Pinus halepensis Mill. forest at the dry timberline that shows sustained photosynthetic activity during 6-7 month summer drought were characterized and quantified under field conditions. Measurements of chlorophyll fluorescence, leaf-level gas exchange and pigment concentrations were made in both control and summer-irrigated plots, providing the opportunity to separate the effects of atmospheric from soil water stress on the photoprotection responses. The proportion of light energy incident on the leaf surface ultimately being used for carbon assimilation was 18% under stress-free conditions (irrigated, winter), declining to 4% under maximal stress (control, summer). Allocation of absorbed light energy to photochemistry decreased from 25 to 15% (control) and from 50% to 30% (irrigated) between winter and summer, highlighting the important role of pigment-mediated energy dissipation processes. Photorespiration or other non-assimilatory electron flow accounted for 15-20% and  10% of incident light energy during periods of high and low carbon fixation, respectively, representing a proportional increase in photochemical energy going to photorespiration in summer but a decrease in the absolute amount of photorespiratory CO loss. Resilience of the leaf photochemical apparatus was expressed in the complete recovery of photosystem II (PSII) efficiency (φPSII) and relaxation of the xanthophyll de-epoxidation state on the diurnal cycle throughout the year, and no seasonal decrease in pre-dawn maximal PSII efficiency (Fv/Fm). The response of CO assimilation and photoprotection strategies to stomatal conductance and leaf water potential appeared independent of whether stress was due to atmospheric or soil water deficits across seasons and treatments. The range of protection characteristics identified provides insights into the relatively high carbon economy under these dry conditions, conditions that are predicted for extended areas in the Mediterranean and other regions due to global climate change. © 2019 The Author(s). Published by Oxford University Press. All rights reserved.
Netzer, Y. ; Munitz, S. ; Shtein, I. ; Schwartz, A. . Structural Memory In Grapevines: Early Season Water Availability Affects Late Season Drought Stress Severity. European Journal of Agronomy 2019, 105, 96-103. Publisher's VersionAbstract
In the future drought events are expected to occur more frequently, with unpredictable rain and heat events. In current research we investigated how different water availability patterns influenced late season plant water status in Vitis vinifera. ‘Cabernet Sauvignon’ grapevines were grown for three consecutive years. We compared the response to five water availability regimes: High, Intermediate, Low (along all season) and High-to-Low (High during the beginning of vegetative seasons switched to low during the rest of season) and Low-to-High (opposite treatment). Midday stem water potential (SWP) was measured weekly to determine the seasonal pattern of drought stress. Xylem anatomy was investigated by trunk vessel diameter measurements, and specific axial xylem conductivity was calculated according to Hagen-Poiseuille's law. Vines exposed to high water availability treatment showed improved seasonal water status along the season, compared to vines in the low treatment. Vines exposed to High-to-Low water regime showed a markedly improved water status at the beginning of the season, but became the most severely stressed toward the end of season. The SWP values were more negative in the High-to-Low regime even when compared to the Low water regime. Water availability at the beginning of the season (during main period of cambial activity) determined the vessel characteristics: high water availability during cambial activity increased vessel diameter and thus specific hydraulic conductivity. Our data strongly indicates that regulated drought stress can be induced by manipulating xylem structural parameters via controlling water availability during the period of stem cambial activity. © 2019 Elsevier B.V.
Munitz, S. ; Schwartz, A. ; Netzer, Y. . Water Consumption, Crop Coefficient And Leaf Area Relations Of A Vitis Vinifera Cv. 'Cabernet Sauvignon' Vineyard. Agricultural Water Management 2019, 219, 86-94. Publisher's VersionAbstract
Most cultivated vineyards worldwide are located in semi-arid and arid regions with a limited water supply. Skilled vineyard water management is considered the main tool for controlling vegetative growth and grape quality and for ensuring vineyard sustainability. Imposing an appropriate drought stress at a suitable phenological stage can improve wine quality with almost no yield reduction. A comprehensive irrigation model enabling precise vineyard irrigation should be based on changes in vine water consumption as a function of climate conditions and canopy area. In 2011, six drainage lysimeters were constructed within a commercial 'Cabernet Sauvignon' vineyard located in the central mountains of Israel. Data were collected during six successive years from 2012 – 2017. The daily vine water consumption, ETc (L day−1), was calculated by subtracting the amount of collected drainage (over a 24 h period) from the amount of applied irrigation during the same time period. Seasonal water consumption (ETc) was 715 mm season−1 on average, while seasonal calculated reference evapotranspiration (ETo) was 1237 mm season−1 on average. Maximal crop coefficient (Kc) was 0.8 – 0.9, meaning that actual water consumption was lower than the calculated reference evapotranspiration. Maximal leaf area index (LAI) was 0.9 to 1.7 m2 m-2. The multi-seasonal linear correlation between LAI and Kc was strongly positive and significant. The robust multiyear relationship between LAI & Kc proves that measuring canopy area of wine grapevines is a reliable approach for estimating their Kc. The LAI to Kc relationship that we have established can be used as a basis for developing a comprehensive irrigation model for wine grapevines that integrates both climatic conditions and canopy area. © 2019 Elsevier B.V.
Cinnamon, Y. ; Genin, O. ; Yitzhak, Y. ; Riov, J. ; David, I. ; Shaya, F. ; Izhaki, A. . High-Resolution Episcopic Microscopy Enables Three-Dimensional Visualization Of Plant Morphology And Development. Plant Direct 2019, 3. Publisher's VersionAbstract
The study of plant anatomy, which can be traced back to the seventeenth century, advanced hand in hand with light microscopy technology and relies on traditional histologic techniques, which are based on serial two-dimensional (2D) sections. However, these valuable techniques lack spatial arrangement of the tissue and hence provide only partial information. A new technique of whole-mount three-dimensional (3D) imaging termed high-resolution episcopic microscopy (HREM) can overcome this obstacle and generate a 3D model of the specimen at a near-histological resolution. Here, we describe the application of HREM technique in plants by analyzing two plant developmental processes in woody plants: oil secretory cavity development in citrus fruit and adventitious root formation in persimmon rootstock cuttings. HREM 3D models of citrus fruit peel showed that oil cavities were initiated schizogenously during the early stages of fruitlet development. Citrus secretory cavity formation, shape, volume, and distribution were analyzed, and new insights are presented. HREM 3D model comparison of persimmon rootstock clones, which differ in their rooting ability, revealed that difficult-to-root clones failed to develop adventitious roots due to their inability to initiate root primordia. © 2019 The Authors. Plant Direct published by American Society of Plant Biologists, Society for Experimental Biology and John Wiley & Sons Ltd.
Meir, S. ; Philosoph-Hadas, S. ; Riov, J. ; Tucker, M. L. ; Patterson, S. E. ; Roberts, J. A. . Re-Evaluation Of The Ethylene-Dependent And-Independent Pathways In The Regulation Of Floral And Organ Abscission. Journal of Experimental Botany 2019, 70, 1461-1467. Publisher's VersionAbstract
Abscission is a developmental process with important implications for agricultural practices. Ethylene has long been considered as a key regulator of the abscission process. The existence of an ethylene-independent abscission pathway, controlled by the complex of INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) peptide and the HAESA (HAE) and HAESA-like2 (HSL2) kinases, has been proposed, based mainly on observations that organ abscission in ethylene-insensitive mutants was delayed but not inhibited. A recent review on plant organ abscission signaling highlighted the IDA-HAE-HSL2 components as the regulators of organ abscission, while the role of auxin and ethylene in this process was hardly addressed. After a careful analysis of the relevant abscission literature, we propose that the IDA-HAE-HSL2 pathway is essential for the final stages of organ abscission, while ethylene plays a major role in its initiation and progression. We discuss the view that the IDA-HAE-HSL2 pathway is ethylene independent, and present recent evidence showing that ethylene activates the IDA-HAE-HSL2 complex. We conclude that the ability of an organ to abscise is tightly linked to cell turgidity in the abscission zone, and suggest that lack of cell turgidity might contribute to the failure of floral organ abscission in the ida mutants. © 2019 The Author(s).
Vinograd, A. ; Zaady, E. ; Kigel, J. . Dynamics Of Soil Nutrients In Abandoned Sheep Corrals In Semi-Arid Mediterranean Planted Forests Under Grazing. Journal of Arid Environments 2019, 164, 38-45. Publisher's VersionAbstract
Traditional sheep grazing in natural and planted forests in the Mediterranean basin is based on night penning in seasonal corrals, where excreta accumulate instead of being returned to the grazed range. Lack of planning and unawareness of the long-term effect of abandoned corrals is negatively affecting the landscape and grazing value of the forests. We studied the dynamics of soil nutrients in a chronosequence of abandoned sheep corrals in planted Eucalyptus forests in two semi-arid sites in Israel. Dung decomposition was a slow process lasting 5–10 years. Soluble-N, P and K in the soil beneath the dung layer decreased gradually. Yet, 15–20 years after corral abandonment K and P were still 2 to 3 times higher than in the surrounding range, while soluble-N decreased within 10–15 years. Biomass production in the abandoned corrals was 2–3 times higher than in the grazed range up to 20 years after abandonment. Corrals act as sinks of soil nutrients that are lost to the grazed range. We propose that a balance between nutrient inputs (i.e. atmospheric deposition, N-fixation) and outputs (i.e. grazing and night penning) is reached in the grazed range at a low level of soil nutrients, which may constrain vegetation productivity. © 2019 Elsevier Ltd
Navon, S. ; Kigel, J. ; Dudai, N. ; Knaanie, A. ; Glasser, T. A. ; Shachter, A. ; Ungar, E. D. . Volatiles And Tannins In Pistacia Lentiscus And Their Role In Browsing Behavior Of Goats (Capra Hircus). Journal of Chemical Ecology 2019. Publisher's VersionAbstract
Goat herding is an important tool in the ecologically sound management of Mediterranean shrublands and woodlands, although effective levels of woody biomass removal by the goats is neither guaranteed nor easy to predict. Preliminary observations indicated that one reason for this may be poor understanding of plant-herbivore interactions that operate intraspecifically at the local spatial scale. We asked, whether goats show intraspecific preferences among neighboring plants when foraging a small local population of Pistacia lentiscus, a dominant tall shrub. First, we characterized and quantified the profile of stored and emitted volatile organic compounds (VOCs) and the PEG-binding capacity of tannins (a proxy for protein binding capacity) in the foliage of P. lentiscus shrubs, sampled within an area of 0.9 ha. We then tested goat preference between pairs of these shrubs that differed in chemical composition. Almost all sampled P. lentiscus shrubs were allocated to one of two distinct VOC chemotypes: one dominated by germacrene D and limonene (designated chemotype L) and the other by germacrene D and α-pinene (chemotype P). In contrast, continuous moderate variability was found in the binding capacity of tannins in the foliage. Goats showed preference for shrubs of chemotype L over those of chemotype P, and their preference was negatively correlated with the binding capacity of tannins. Possible influences of VOCs on goat preference that may explain the observed patterns are discussed in the light of possible context-dependent interpretation of plant VOC signals by large mammalian herbivores. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.