Institute of Plant science

HUJ, Israel

Institute of Plant science

HUJ, Israel
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Since time immortal, plants have been used for maintaining health and curing disease. With cancer being a widespread threat to humanity, plants play an important role in cancer prevention, as well as in therapy. Medicinal plants provide new active chemopreventive molecules. In addition, treatment with plants can ease side-effects as well as provide support to the fears and anxieties of the sick. In this review, methods of exploring new plants and new active plant-derived compounds are described, including ethnobotanical research and screening procedures. Three newly researched medicinal plants, native of Israel, are selected, and new research findings related to their anticancer activities are presented. The plants are: Crocus sativus, Vitex agnus-cactus and Withania somnifera. All three plants are known in traditional medicine and their therapeutical uses are documented. Most findings are preliminary and further studies are required for clinical applications.

Sheehan H.,Institute of Plant science | Hermann K.,Institute of Plant science | Kuhlemeier C.,Institute of Plant science
Cold Spring Harbor Symposia on Quantitative Biology | Year: 2012

A major function ofangiosperm flowers isthe recruitment of animal pollinators that serve to transfer pollen among conspecific plants. Distinct sets of floral characteristics, called pollination syndromes, are correlated with visitation by specific groups of pollinators. Switches among pollination syndromes have occurred in many plant families. Such switches must have involved coordinated changes in multiple traits and multiple genes. Two well-studied floral traits affecting pollinator attraction are petal color and scent production. We review current knowledge about the biosynthetic pathways for floral color and scent production and their interaction at the genetic and biochemical levels. A key question in the field concerns the genes that underlie natural variation in color and scent and how such genes affect pollinator preference, reproductive isolation, and ultimately speciation. © 2012 Cold Spring Harbor Laboratory Press; all rights reserved.

Koltai H.,Institute of Plant science
Trends in Plant Science | Year: 2014

Strigolactones, previously identified as active stimuli of seed germination in parasitic plants, are now recognized as a new group of plant hormones that are active in both shoots and roots. Here, we review recent insights into the concepts of strigolactones-signal transduction and their mode of action. Although strigolactones are sensed via a cell-specific reception system, at least some aspects of their activity are conducted in a non-cell-autonomous fashion. Strigolactones also affect trafficking and plasma-membrane localization of the auxin transporter PIN, thereby regulating auxin flux. We present a model for strigolactone-signal transduction that might also explain the integration of strigolactones into other hormone-signaling pathways via the regulation of PIN auxin transporters. © 2014 Elsevier Ltd.

Koltai H.,Institute of Plant science
Plant Science | Year: 2014

Strigolactones produced by various plant species are involved in the development of different plant parts. They are also exuded by plant roots to the rhizosphere, where they are involved in the induction of seed germination of the parasitic plants Striga and Orobanche, hyphal branching of the symbiotic arbuscular mycorrhizal fungi (AMF), and the symbiotic interaction with Rhizobium. In the present discussion paper, the essentialness of strigolactones as communication signals in these plant interactions is discussed in view of the existence of other plant-derived substances that are able to promote these plant interactions. In addition, the importance of strigolactones for determination of interaction specificity is discussed based on current knowledge on strigolactone composition, perception and delivery. The different activities of strigolactones in plant development and in the rhizosphere suggest their possible use in agriculture. However, despite efforts made in this direction, there is no current, practical implementation. Possible reasons for the encountered difficulties and suggested solutions to promote strigolactone use in agriculture are discussed. © 2014 Elsevier Ireland Ltd.

Ashkenazy H.,Tel Aviv University | Penn O.,Tel Aviv University | Doron-Faigenboim A.,Institute of Plant science | Cohen O.,Tel Aviv University | And 3 more authors.
Nucleic Acids Research | Year: 2012

Ancestral sequence reconstruction is essential to a variety of evolutionary studies. Here, we present the FastML web server, a user-friendly tool for the reconstruction of ancestral sequences. FastML implements various novel features that differentiate it from existing tools: (i) FastML uses an indel-coding method, in which each gap, possibly spanning multiples sites, is coded as binary data. FastML then reconstructs ancestral indel states assuming a continuous time Markov process. FastML provides the most likely ancestral sequences, integrating both indels and characters; (ii) FastML accounts for uncertainty in ancestral states: it provides not only the posterior probabilities for each character and indel at each sequence position, but also a sample of ancestral sequences from this posterior distribution, and a list of the k-most likely ancestral sequences; (iii) FastML implements a large array of evolutionary models, which makes it generic and applicable for nucleotide, protein and codon sequences; and (iv) a graphical representation of the results is provided, including, for example, a graphical logo of the inferred ancestral sequences. The utility of FastML is demonstrated by reconstructing ancestral sequences of the Env protein from various HIV-1 subtypes. FastML is freely available for all academic users and is available online at © 2012 The Author(s).

Bar-Ziv A.,Institute of Plant science
Plant signaling & behavior | Year: 2012

The V2 protein of Tomato yellow leaf curl geminivirus (TYLCV) is an RNA-silencing suppressor that counteracts the innate immune response of the host plant. However, this anti-host defense function of V2 may include targeting of other defensive mechanisms of the plant. Specifically, we show that V2 recognizes and directly binds the tomato CYP1 protein, a member of the family of papain-like cysteine proteases which are involved in plant defense against diverse pathogens. This binding occurred both in vitro and in vivo, within living plant cells. The V2 binding site within mCYP1 was identified in the direct proximity to the papain-like cysteine protease active site.

Mahesh A.,Institute of Plant science | Jeyachandran R.,St. Joseph's College
Plant Biosystems | Year: 2011

Hairy roots were efficiently induced from leaf and petiole explants of Taraxacum officinale after infection with the Agrobacterium rhizogenes strains A4 and ATCC 15834. The highest frequency of hairy root initiation was observed after transformation of leaf explants with the A4 strain. Hairy roots developed from leaf tissue produced more biomass than nontransformed roots. A quantitative study of sesquiterpene lactones showed that A. rhizogenes induced root cultures accumulated higher levels of these compounds than non-transformed and wild plant roots. The present results demonstrate that T. officinale hairy root culture is a valuable alternative approach for the production of sesquiterpene lactones. © 2011 Società Botanica Italiana.

Kamenetsky R.,Institute of Plant science
Acta Horticulturae | Year: 2011

Ornamental geophytes belong to numerous botanical taxa and show remarkable diversity with regard to morphology, developmental biology, genetic control and response to the environment. Flower development of geophytes is greatly influenced both by the genetics of the individual plant and by environmental factors; their interactions affect a series of molecular and biochemical processes leading to the transition of the plant from vegetative to reproductive development. While the morphological and physiological aspects of florogenesis have been studied in several bulbous species, there is still only limited information on the genetic control of meristem transition, formation of inflorescence, individual flowers, and flower parts. Elucidating the genetic control of florogenesis in geophytes is important, not only for better understanding of their developmental biology, but also because of their agronomic and economic importance. Molecular characterization of genes involved in flower morphology could help to develop novel floral architecture in flower bulbs by classical breeding or by genetic manipulations. Until now, most genetic studies have been performed on commercially important crops. However, a model bulbous species has to stand several specific criteria: a short juvenile period, easy pollination and seed germination, well studied morphological and physiological aspects, an established transformation system. Recent results, prospects and future investigations of physiological, biochemical and molecular mechanisms of florogenesis in ornamental geophytes are discussed.

Osem Y.,Institute of Plant science | Lavi A.,Institute of Plant science | Rosenfeld A.,Ecolo GIS
Biological Invasions | Year: 2011

The expansion of P. halepensis from plantations into natural sites of high conservation value is becoming a frequent occurrence across the Mediterranean zone of Israel. We studied how colonization of Pinus halepensis in natural Mediterranean habitats is related to afforestation, cattle grazing and fire. The study was conducted in a Mediterranean garrigue (Shrubland) located in Ramat Hanadiv Nature Park, southern Mt. Carmel region, Israel. The study area (ca. 350 ha) was divided into cells (100 × 100 m) each of which was categorized with respect to distance from planted pines, grazing (grazed since 1990/ungrazed), fire (burned in 1980/unburned), and vegetation structure (garrigue, dense garrigue, dense woodland). The location of colonizing pines, typically three m or more in height, was determined using an aerial photograph. Density of colonizing pines decreased linearly with the distance from planted pines within 300 m from planted pines with a long tail that extended out to ca 1,000 m. Over 90% of the colonizing pines that were found were located within a distance of 300 m (56% of the park area) from planted pines. Colonization was about two times greater under grazing than without grazing. The effects of fire and of the interaction fire × grazing were found insignificant. A separate analysis reveled that colonization was about 2 times larger in patches of sparse woody cover than in those of dense cover. In conclusion, pine colonization was mainly determined by the proximity to seed sources. Additionally, pine colonization was enhanced by cattle grazing probably through reduction of the natural vegetation cover. © 2010 Springer Science+Business Media B.V.

Kamenetsky R.,Institute of Plant science
Acta Horticulturae | Year: 2014

Flowering involves a variety of molecular, physiological, and biochemical mechanisms regulating the proper timing and correct development of the reproductive organs. Sensing and integration of the external cues (temperature, photoperiod, irradiance, and stress) by the plant are necessary for the optimal timing of flowering during the year, for synchronized flowering within a population, and for successful seed development. Therefore, horticultural manipulations aimed at directing flowering to specific periods usually make use of these cues. In geophytes, florogenesis can be divided into several consecutive steps: induction, initiation, differentiation (organogenesis), maturation and growth of floral organs, anthesis and senescence. A major distinction can be made between the geophytes in which flower initiation takes place within the bulb during the "dormancy" period prior to growth ("Tulip type"), and those in which flowering is initiated during active growth, following the development of several leaves ("Lily type"). The commercial cultivars of L. longiflorum require low temperatures and a long photoperiod for florogenesis. Although breeding of commercially important hybrids has great commercial value, only limited data are available on molecular regulation of flowering. To date, two basic strategies have been used to isolate genes involved in florogenesis. The first is based on sequence homology between species. Numerous homologues of genes from model plants have recently been isolated from geophytes. The second approach is broader and involves the determination of a large number of genes, using cDNA libraries and isolation of the genes expressed in specific tissue locations or physiological states. Recently, next generation sequencing (NGS) technology has been used to sequence the transcriptomes (RNA-seq) of lily cultivars. Investigations in the coming decade are expected to improve our understanding of this process, thus contributing to the development of breeding techniques and the production of new hybrids.

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