The olive tree is generally characterized by relatively low final fruit set consequential to a significant rate of undeveloped pistils, pistil abortion, and flower and fruitlet abscission. These processes are acknowledged to be governed by competition for resources between the developing vegetative and reproductive organs. To study the role of phosphorus (P) nutritional level on reproductive development, trees were grown under four levels of P for three years in large containers. Phosphorus nutritional level was positively related to rate of reproductive bud break, inflorescence weight, rate of hermaphrodite flowers, pistil weight, fruitlet persistence, fruit set and the consequential total number of fruits. The positive impact of P nutrition on the productivity parameters was not related to carbohydrate reserves or to carbohydrate transport to the developing inflorescence. Phosphorous deficient trees showed significant impairment of assimilation rate, and yet, carbohydrates were accumulated in inflorescences at levels comparable to or higher than trees receiving high P. In contrast to female reproductive organs, pollen viability was consistently higher in P deficient trees, possibly due to the enhanced carbohydrate availability. Overall, the positive effect of P on female reproductive development was found to be independent of the total carbohydrate availability. Hence, P is speculated to have a direct influence on reproductive processes. © 2016 Erel et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Abscission of flower pedicels and leaf petioles of tomato (Solanum lycopersicum) can be induced by flower removal or leaf deblading, respectively, which leads to auxin depletion, resulting in increased sensitivity of the abscission zone (AZ) to ethylene. However, the molecular mechanisms that drive the acquisition of abscission competence and its modulation by auxin gradients are not yet known. We used RNA-Sequencing (RNA-Seq) to obtain a comprehensive transcriptome of tomato flower AZ (FAZ) and leaf AZ (LAZ) during abscission. RNA-Seq was performed on a pool of total RNA extracted from tomato FAZ and LAZ, at different abscission stages, followed by de novo assembly. The assembled clusters contained transcripts that are already known in the Solanaceae (SOL) genomics and NCBI databases, and over 8823 identified novel tomato transcripts of varying sizes. An AZ-specific microarray, encompassing the novel transcripts identified in this study and all known transcripts from the SOL genomics and NCBI databases, was constructed to study the abscission process. Multiple probes for longer genes and key AZ-specific genes, including antisense probes for all transcripts, make this array a unique tool for studying abscission with a comprehensive set of transcripts, and for mining for naturally occurring antisense transcripts. We focused on comparing the global transcriptomes generated from the FAZ and the LAZ to establish the divergences and similarities in their transcriptional networks, and particularly to characterize the processes and transcriptional regulators enriched in gene clusters that are differentially regulated in these two AZs. This study is the first attempt to analyze the global gene expression in different AZs in tomato by combining the RNA-Seq technique with oligonucleotide microarrays. Our AZ-specific microarray chip provides a cost-effective approach for expression profiling and robust analysis of multiple samples in a rapid succession. © 2016 Sundaresan, Philosoph-Hadas, Riov, Mugasimangalam, Kuravadi, Kochanek, Salim, Tucker and Meir.

A novel simple, fast qualitative method for detection and differentiation of PVY strains in potatoes by the LightCycler technology is described. Fluorescent-labeled probe designed to contain variable degree of homology with a ‘target sequence’ of several known reference PVY strains was annealed to PCR products of these viruses followed by a graded melting analysis. The specific characteristics of the melting curves enable the detection, distinction and differentiation of each of following four known PVY strains O-FL, O-RB, N and NTN, in a single reaction obviating the need for size or nucleotide sequence analyses. In addition, it was demonstrated that virus extracts from plants infected with more than one strain can be resolved using this procedure. The melting-curves of extracts from 55 market size tubers harvested randomly from commercial fields and compared with those of the reference virus strains, revealed the presence of O-FL, O-RB and NTN strains of PVY. © 2016, The Potato Association of America.

More than 50 species of the genus Allium have been cultivated worldwide for sustenance, flavor, and medicinal purposes, as well as for ornamentals, from the tropics to the temperate zone. In most alliums, intact tissues contain odorless, nonvolatile sulfur-containing molecules that upon cells' disruption break down enzymatically to form volatile flavor compounds that are responsible for the characteristic odor and taste of these species. The genetic makeup, photoperiod, and both storage and growth temperatures are the main factors controlling bulbing and florogenesis in these plant species. The most common Allium food crops are bulb onion garlic, leek, shallot, chives, and Welsh onion. Most fertile cultivated alliums are raised from seed, transplants, or sets. However, some sterile species, such as garlic, elephant garlic, rocambole tree onion, topsetting onions, and shallot are propagated vegetatively. During millennia of cultivation, no natural co-evolution with biotic and abiotic agents has taken place. Hence, most cultivated alliums lack many important traits, including resistance to pests and environmental stresses. Current efforts and employment of both classical and novel tools for genetic and plant physiology studies are expected to accelerate improvements in terms of distribution, yield, and quality of these important crops. © 2017 Elsevier Ltd. All rights reserved.

A concise description of the history, classification, cytology, and botany of potato is presented. The effects of the environment on the morphology, physiology, and development of the potato plant and the adverse effects of high temperatures, drought, and salinity on growth, tuber development, and tuber quality are described. Tuber dormancy and its control in association with storage and with 'seed' tubers' vigor are discussed. Principles of crop production, storage, and tuber quality are presented. © 2017 Elsevier Ltd. All rights reserved.

Well-defined productivity-precipitation relationships of ecosystems are needed as benchmarks for the validation of land models used for future projections. The productivity-precipitation relationship may be studied in two ways: the spatial approach relates differences in productivity to those in precipitation among sites along a precipitation gradient (the spatial fit, with a steeper slope); the temporal approach relates interannual productivity changes to variation in precipitation within sites (the temporal fits, with flatter slopes). Precipitation-reduction experiments in natural ecosystems represent a complement to the fits, because they can reduce precipitation below the natural range and are thus well suited to study potential effects of climate drying. Here, we analyse the effects of dry treatments in eleven multiyear precipitation-manipulation experiments, focusing on changes in the temporal fit. We expected that structural changes in the dry treatments would occur in some experiments, thereby reducing the intercept of the temporal fit and displacing the productivity-precipitation relationship downward the spatial fit. The majority of experiments (72%) showed that dry treatments did not alter the temporal fit. This implies that current temporal fits are to be preferred over the spatial fit to benchmark land-model projections of productivity under future climate within the precipitation ranges covered by the experiments. Moreover, in two experiments, the intercept of the temporal fit unexpectedly increased due to mechanisms that reduced either water loss or nutrient loss. The expected decrease of the intercept was observed in only one experiment, and only when distinguishing between the late and the early phases of the experiment. This implies that we currently do not know at which precipitation-reduction level or at which experimental duration structural changes will start to alter ecosystem productivity. Our study highlights the need for experiments with multiple, including more extreme, dry treatments, to identify the precipitation boundaries within which the current temporal fits remain valid. © 2016 John Wiley & Sons Ltd.

Rapid and uniform seed germination and seedling emergence under diverse environmental conditions is a desirable characteristic for crops. Common bean genotypes (Phaseolus vulgaris L.) differ in their low temperature tolerance regarding growth and yield. Cultivars tolerant to low temperature during the germination and emergence stages and carriers of the grain quality standards demanded by consumers are needed for the success of the bean crop. The objectives of this study were (i) to screen the seedling emergence and the phenotypic response of bean germplasm under a range of temperatures in controlled chamber and field conditions to display stress-tolerant genotypes with good agronomic performances and yield potential, and (ii) to compare the emergence of bean seedlings under controlled environment and in open field conditions to assess the efficiency of genebanks standard germination tests for predicting the performance of the seeds in the field. Three trials were conducted with 28 dry bean genotypes in open field and in growth chamber under low, moderate, and warm temperature. Morpho-agronomic data were used to evaluate the phenotypic performance of the different genotypes. Cool temperatures resulted in a reduction of the rate of emergence in the bean genotypes, however, emergence and early growth of bean could be under different genetic control and these processes need further research to be suitably modeled. Nine groups arose from the Principal Component Analysis (PCA) representing variation in emergence time and proportion of emergence in the controlled chamber and in the open field indicating a trend to lower emergence in large and extra-large seeded genotypes. Screening of seedling emergence and phenotypic response of the bean germplasm under a range of temperatures in controlled growth chambers and under field conditions showed several genotypes, as landraces 272, 501, 593, and the cultivar Borlotto, with stress-tolerance at emergence, and high yield potential that could be valuable genetic material for breeding programs. Additionally, the potential genetic erosion in genebanks was assessed. Regarding bean commercial traits, under low temperature at sowing time seed reached larger size, and crop yield was higher compared to warmer temperatures at the sowing time. Therefore, early sowing of bean is strongly recommended. © 2016 De Ron, Rodiño, Santalla, González, Lema, Martín and Kigel.

Nitrophilic thistles such as milk thistle (Sylibum marianum) and Syrian thistle (Notobasis syriaca) encroach rangeland areas where animals gather and defecate, in particular around watering and feeding points. High densities of milk and Syrian thistles (MST) diminish forage yields and detract from the amenity value of these areas. The aims of the present study were: (i) to test the safety of feeding MST to adult goats; (ii) to determine if preconditioning adult goats to MST, by feeding it indoors together with concentrate, enhances preference for MST when they graze MST-rich pastures; and (iii) to test for generational transfer by comparing the propensity to consume MST and the preference for MST over clover hay for weaned kids that previously suckled from does that were, or were not, preconditioned to consume MST fed as green fodder. We found that eating MST was not toxic to adult goats. Over six observation sessions of one hour, preconditioned goats devoted 50% more time to consuming MST than non-conditioned counterparts (30.3% versus 20.6%, respectively; P = 0.0005), and kids that experienced the preconditioning period together with their does tended (P = 0.08) to show a greater preference for MST over clover hay than their counterparts born to non-conditioned adults. Although the efficacy in depleting the seed bank has yet to be verified, from the point of view of the animal, goats may be used in targeted grazing of milk and Syrian thistles. © 2016 Elsevier B.V.

Main conclusion: Global warming will increase the incidence of metabolism-based reduced herbicide efficacy on weeds and, therefore, the risk for evolution of non-target site herbicide resistance. Climate changes affect food security both directly and indirectly. Weeds are the major biotic factor limiting crop production worldwide, and herbicides are the most cost-effective way for weed management. Processes associated with climatic changes, such as elevated temperatures, can strongly affect weed control efficiency. Responses of several grass weed populations to herbicides that inhibit acetyl-CoA carboxylase (ACCase) were examined under different temperature regimes. We characterized the mechanism of temperature-dependent sensitivity and the kinetics of pinoxaden detoxification. The products of pinoxaden detoxification were quantified. Decreased sensitivity to ACCase inhibitors was observed under elevated temperatures. Pre-treatment with the cytochrome-P450 inhibitor malathion supports a non-target site metabolism-based mechanism of herbicide resistance. The first 48 h after herbicide application were crucial for pinoxaden detoxification. The levels of the inactive glucose-conjugated pinoxaden product (M5) were found significantly higher under high- than low-temperature regime. Under high temperature, a rapid elevation in the level of the intermediate metabolite (M4) was found only in pinoxaden-resistant plants. Our results highlight the quantitative nature of non-target-site resistance. To the best of our knowledge, this is the first experimental evidence for temperature-dependent herbicide sensitivity based on metabolic detoxification. These findings suggest an increased risk for the evolution of herbicide-resistant weeds under predicted climatic conditions. © 2016, Springer-Verlag Berlin Heidelberg.

To provide sufficient food and fiber to the increasing global population, the technologies associated with crop protection are growing ever more sophisticated but, at the same time, societal expectations for the safe use of crop protection chemistry tools are also increasing. The goal of this perspective is to highlight the key issues that face future leaders in crop protection, based on presentations made during a symposium titled "Developing Global Leaders for Research, Regulation and Stewardship of Crop Protection Chemistry in the 21st Century", held in conjunction with the IUPAC 13th International Congress of Pesticide Chemistry in San Francisco, CA, USA, during August 2014. The presentations highlighted the fact that leaders in crop protection must have a good basic scientific training and understand new and evolving technologies, are aware of the needs of both developed and developing countries, and have good communication skills. Concern is expressed over the apparent lack of resources to meet these needs, and ideas are put forward to remedy these deficiencies. © 2015 American Chemical Society.

Carrot is a high-value cash crop that is grown in Israel throughout the year. Egyptian broomrape is a chlorophyll-lacking, obligate, root holoparasite that parasitizes members of many botanical families, including the Apiaceae. At high infestation levels, Egyptian broomrape can cause total yield loss in carrot. A protocol has been developed for the control of Egyptian broomrape in carrot. Because carrots are grown in Israel under fall, winter, and spring conditions, information about the relations between the efficacy of control and temperature is important. Therefore, the objective of this study was to investigate the response of carrot and Egyptian broomrape to herbicides at different phenological stages under varying temperature regimes. This study was conducted under temperature-controlled conditions in a multiclimate greenhouse and in a net house. Applications of the imidazolinone herbicides imazapic and imazamox (each applied at 4.8 g ai ha-1) injured carrot plants and reduced yield and yield quality. Glyphosate effectively controlled Egyptian broomrape and did not negatively affect the carrot plants when applied three times at ≤-108 g ae ha-1. High temperatures increased the carrot plants' sensitivity to glyphosate. This study found that three applications of glyphosate at 108 g ae ha-1 can prevent Egyptian broomrape damage without causing any damage to the carrot crop. Our results indicate that weather conditions can affect herbicide phytotoxicity in carrot. The highest temperature at the time of herbicide application corresponded to the strongest observed phytotoxic effect. To summarize, effective Egyptian broomrape control can be achieved by three sequential foliar applications of glyphosate (108 g ae ha-1), beginning during the early parasitism stage (i.e., small tubercles). Moreover, applying glyphosate on carrot at high temperature (i.e., 28/22 C day/night temperatures) can injure carrot plants and reduce control efficacy. Nomenclature: Glyphosate; imazamox; imazapic; Egyptian broomrape, Orobanche aegyptiaca Pers. ORAAE; carrot, Daucus carota L. var. sativus Hoffm. © 2016 Weed Science Society of America.

The members of the genus Cuscuta (common name: dodder) are obligate holoparasitic plants that are found throughout the agricultural regions of the world. Of all of the species of dodder, field dodder (Cuscuta campestris) causes the most damage to crops. This species parasitizes the shoots of broadleaf plant crops and weeds. We conducted a series of field dodder seed germination tests in controlled-temperature chambers, in order to describe the effect of temperature on field dodder germination and develop a germination model based on the obtained data. The best fit was obtained when temperature data and time were transformed to thermal time using the beta-function model. The field dodder germination model can serve as a tool for knowledge-based predictions of germination and emergence timing, to allow for the implementation of effective mechanical and chemical management measures. Nomenclature: Field dodder; Cuscuta campestris Yuncker. © 2016 Weed Science Society of America.

BACKGROUND: Conyza bonariensis and C. canadensis are troublesome weeds, particularly in fields with minimum tillage, on roadsides and in perennial crops. The distribution of these difficult-to-control species is further increased by the spread of glyphosate-resistant populations. A preliminary investigation has demonstrated the existence of various degrees of glyphosate tolerance/resistance in these populations, underscoring the need to examine the relationship between glyphosate efficacy and plant growth conditions. RESULTS: In populations exposed to glyphosate at different temperatures, glyphosate tolerance increased linearly as the temperature was increased, whereas when grown under the same temperatures, they largely responded similarly to the herbicide. Furthermore, the sensitivity of plants to glyphosate decreased significantly with plant age and increased following temporal exposure to shading. Dose-response studies confirmed the glyphosate resistance of four C. bonariensis populations that were 8-30 times more resistant to glyphosate than the most glyphosate-sensitive population. These populations retained their characteristic glyphosate resistance even under unfavourable growth conditions. CONCLUSION: These findings indicate that the effect of glyphosate on both Conyza species is strongly linked to growing conditions. This has great importance for our understanding of glyphosate resistance and for control of these weeds in agricultural systems. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Carrot, a highly profitable crop in Israel, is severely damaged by Phelipanche aegyptiaca parasitism. Herbicides can effectively control the parasite and prevent damage, but for optimal results, knowledge about the soil–subsurface phenological stage of the parasite is essential. Parasitism dynamics models have been successfully developed for the parasites P. aegyptiaca, Orobanche cumana, and Orobanche minor in the summer crops, tomato, sunflower, and red clover, respectively. However, these models, which are based on a linear relationship between thermal time and the parasitism dynamics, may not necessarily be directly applicable to the P. aegyptiaca–carrot system. The objective of the current study was to develop a thermal time model to predict the effect of P. aegyptiaca parasitism dynamics on carrot growth. For development and validation of the models, data was collected from a temperature-controlled growth experiment and from 13 plots naturally infested with P. aegyptiaca in commercial carrot fields. Our results revealed that P. aegyptiaca development is related to soil temperature. Moreover, unlike P. aegyptiaca parasitism in sunflower and tomato, which could be predicted both a linear model, P. aegyptiaca parasitism dynamics on carrot roots required a nonlinear model, due to the wider range of growth temperatures of both the carrot and the parasite. Hence, two different nonlinear models were developed for optimizing the prediction of P. aegyptiaca parasitism dynamics. Both models, a beta function model and combined model composed of a beta function and a sigmoid curve, were able to predict first P. aegyptiaca attachment. However, overall P. aegyptiaca dynamics was described more accurately by the combined model (RMSE = 14.58 and 10.79, respectively). The results of this study will complement previous studies on P. aegyptiaca management by herbicides to facilitate optimal carrot growth and handling in fields infested with P. aegyptiaca. © 2016 Cochavi, Rubin, Achdari and Eizenberg.

Begomoviruses are an emerging group of plant viruses, exclusively transmitted by the whitefly Bemisia tabaci in a persistent-circulative manner. Despite the economic importance of both, very little is known about begomovirus-whitefly interactions. Specific topics of interest that have been a subject of intensive research during the last decade include the route of the virus in the insect organs and cells, the influence of the virus on the insect’s behavior and transcriptome, the proteins that mediate begomovirus translocation and the role of bacterial symbionts in this phenomenon. These topics are summarized and discussed in this chapter. © Springer International Publishing Switzerland 2016.

Thanks to the application of new technologies such as whole-genome sequencing, analysis of transcriptome and proteome of insect pest to agriculture, great progress has been made in understanding the life style, reproduction, evolution and nuisance to crops caused by insect pests such as aphids, planthoppers, and whiteflies. We believe that time has come to summarize progress and to have a glance over the horizon. In this Book experts in the field discuss novel means to increase the different kinds of resistances of plants to better limit the effects of pest, to understand and disturb the hormonal regulation of embryogenesis, molting, metamorphosis and reproduction, to determine the function of insect genes in diverse processes such as metabolism, interaction with plants, virus transmission, development, and adaptation to a changing environment. The knowledge presented here is discussed with the aim of further improving control strategies of insect pestsman";mso-hansi-theme-font:minor-bidi;mso-bidi-theme-font:minor-bidi; mso-ansi-language:NL;mso-fareast-language:NL;mso-bidi-language:AR-SA">. © Springer International Publishing Switzerland 2016.

The whitefly Bemisia tabaci is a major pest to agricultural crops. It transmits begomoviruses, such as Tomato yellow leaf curl virus (TYLCV), in a circular, persistent fashion. Transcriptome analyses revealed that B. tabaci knottin genes were responsive to various stresses. Upon ingestion of tomato begomoviruses, two of the four knottin genes were upregulated, knot-1 (with the highest expression) and knot-3. In this study, we examined the involvement of B. tabaci knottin genes in relation to TYLCV circulative transmission. Knottins were silenced by feeding whiteflies with knottin dsRNA via detached tomato leaves. Large amounts of knot-1 transcripts were present in the abdomen of whiteflies, an obligatory transit site of begomoviruses in their circulative transmission pathway; knot-1 silencing significantly depleted the abdomen from knot-1 transcripts. Knot-1 silencing led to an increase in the amounts of TYLCV ingested by the insects and transmitted to tomato test plants by several orders of magnitude. This effect was not observed following knot-3 silencing. Hence, knot-1 plays a role in restricting the quantity of virions an insect may acquire and transmit. We suggest that knot-1 protects B. tabaci against deleterious effects caused by TYLCV by limiting the amount of virus associated with the whitefly vector. © 2016 by the authors; licensee MDPI, Basel, Switzerland.

Despite its total reliance on its host plant, the holoparasitePhelipanche aegyptiacasuffers from a deficiency of aromatic amino acids upon exposure to glyphosate.

Previous studies on cytokinin (CK) and drought have suggested that the hormone has positive and negative effects on plant adaptation to restrictive conditions. This study examined the effect of CK on transpiration, stomatal activity, and response to drought in tomato (Solanum lycopersicum) plants. Transgenic tomato plants overexpressing the Arabidopsis thaliana CK-degrading enzyme CK oxidase/dehydrogenase 3 (CKX3) maintained higher leaf water status under drought conditions due to reduced whole-plant transpiration. The reduced transpiration could be attributed to smaller leaf area and reduced stomatal density. CKX3-overexpressing plants contained fewer and larger pavement cells and fewer stomata per leaf area than wild-type plants. In addition, wild-type leaves treated with CK exhibited enhanced transpiration and had more pavement cells and increased numbers of stomata per leaf area than untreated leaves. Manipulation of CK levels did not affect stomatal movement or abscisic acid-induced stomatal closure. Moreover, we found no correlation between stomatal aperture and the activity of the CK-induced promoter Two-Component Signaling Sensor (TCS) in guard cells. Previous studies have shown that drought reduces CK levels, and we propose this to be a mechanism of adaptation to water deficiency: the reduced CK levels suppress growth and reduce stomatal density, both of which reduce transpiration, thereby increasing tolerance to prolonged drought conditions.

Thaumatin, a supersweet protein from the African plant katemfe (Thaumatococcus daniellii Benth.), is a promising zero-calorie sweetener for use in the food and pharmaceutical industries. Due to limited natural sources of thaumatin, its production using transgenic plants is an advantageous alternative. We report a simple protocol for purification of recombinant thaumatin II from transgenic tomato. Thaumatin was extracted from ripe tomato fruit in a low-salt buffer and purified on an SP-Sephacryl column. Recombinant thaumatin yield averaged 50 mg/kg fresh fruit. MALDI-MS analysis showed correct processing of thaumatin in tomato plants. The recombinant thaumatin was indistinguishable from the native protein in a taste test. The purified tomato-derived thaumatin had an intrinsic sweetness with a threshold value in taste tests of around 50 nM. These results demonstrate the potential of an expression system based on transgenic tomato plants for production of recombinant thaumatin for the food and pharmaceutical industries.