Research in my lab 1. Strigolactones as new plant hormones and as regulators of mycorrhiza symbiosis To gain an insight into the mechanism of strigolactons activity on plant development and plant-mycorrhiza interaction, we are studying model systems of tomato and Arabidopsis, examining an array of mutants and reporter-gene-expressing lines. Today, strigolactones are considered a new group of plant hormones, or their biosynthetic precursors (Gomez-Roldan and others, 2008, Umehara and others, 2008). They are produced in many plants and their synthesis-associated genes are present in all plants (Klee, 2008). Years ago, strigolactones were identified as inducers of witchweed germination (Cook and others, 1972) and then, in multiple studies, as signals for plant interactions with both witchweed and mycorrhizal fungi (e.g., Matsuva and others, 2005; Akiyama and Hayashi, 2006; Bouwmeester and others, 2007; Besserer and others, 2008; Goldwasser and others, 2008; Yoneyama and others, 2008). The production of strigolactones has been demonstrated in many plant species (e.g, Gomez-Roldan and others, 2008; Umehara and others, 2008; Sato and others, 2005), mainly in the roots (Foo and others, 2001), and to be derived from the carotenoid pathway (Matusova and others, 2005) via the activity of various oxygenases (Gomez-Roldan and others, 2008; Umehara and others, 2008 and references therein).
Very recently, strigolactones have been suggested to play a pivotal role in the regulation of above-ground plant architecture by inhibiting shoot branching; this was deduced from studies of Arabidopsis, pea and rice mutants which were defective in strigolactone production or perception (Gomez-Roldan and others, 2008; Umehara and others, 2008). However, the mechanisms underlying the effects of strigolactones on plant growth remain elusive. Hence,in my lab, we are studying the mechanism of strigolactone action, both as modulators of plant structure, and as regulators of interaction between plants and the arbuscular mycorrhiza fungi. Our peer reviewed publications in this subject: Koltai H., Dor E., Hershenhorn J., Joel D.M., Weininger S., Lekalla S., Shealtiel H., Bahattacharya C., Eliahu E., Resnick N., Barg R. and Kapulnik Y. (2009). Strigolactones' Effect on Root Growth and Root-Hair Elongation may be Mediated by Auxin-Efflux Carriers. Journal of Plant Growth Regulation, 29:129-136. Dor E., Alperin B., Wininger S., Ben-Dor B., Somvanshi V.S., Koltai H., Kapulnik Y. and Hershenhorn J. (2009). Characterization of a novel tomato mutant resistant to Orobanche and Phelipanche spp. weedy parasites. Euphytica, 171: 371-380 Koltai H., LekKala S.P., Bahattacharya C., Mayzlish-Gati E., Resnick N., Wininger S., Dor E., Yoneyama K., Yoneyama K., Hershenhorn J., Joel D.M. and Kapulnik Y. (2010). A Tomato Strigolactone-Impaired Mutant Displays Aberrant Shoot Morphology and Plant Interactions. Journal of Experimental Botany, 61: 1739-1749 Mayzlish-Gati E., LekKala S.P., Resnick N., Wininger S., Bhattacharya C., Lemcoff J.H., Kapulnik Y., Koltai H. (2010). Strigolactones are positive regulators of light-harvesting genes in tomato. Journal of Experimental Botany, 61: 3129-3136 Kapulnik Y., Delaux P-M, Resnick N, Mayzlish-Gati E, Wininger S, Bhattacharya C, Séjalon-Delmas N, Combier J-P, Bécard G, Belausov E, Beeckman T, Dor E, Hershenhorn J, Koltai H. (2010). Strigolactones affect lateral root formation and root hair elongation in Arabidopsis. Planta, in press. Books, book chapters and invited reviews Koltai H. and Kapulnik Y. (2010). Strigolactones as mediators of plant growth responses to environmental conditions. Plant Signaling and Behavior, in press. 
2. Application of Mycorrhiza to a variety of ornamental crops and herbs
In intensive agriculture, which takes place in Israel in semi-arid regions, under greenhouse conditions, soil disinfection methods are applied routinely. As a result, a reduction in the native Arbuscular Mycorrhiza Fungi (AMF) population is observed. The application of AMF inoculum to the soil has been proven to be effective in preventing stunting syndrome in plants, and in enhancement of their growth, and increasing in their resistance to abiotic and biotic stress. This was demonstrated especially for pepper and chive. However, for economic and practical reasons, AMF inoculum application is not yet feasible for many crops. Therefore, it has become important to introduce convenient and inexpensive method(s) for applying AM inoculum, which will enable the direct application of AM inoculum in the greenhouse, before or at the time of planting. Ornamental crops are high-cash crops, and are being grown especially in semi-arid regions, under greenhouse conditions in Israel. Our lab is aimed at expanding AMF usage for a variety of ornamental crops. For that purpose, we have examined avenues for application of AMF, for their efficacy in supporting colonization of various host roots. An example for the effect of AMF on growth is demonstrated below, for Lisianthus. One of our test case is the usage of AMF for lisianthus, an ornamental crop, one of the major crops grown in Israel. We examine several different methods of AMF application and their effect on growth and yield of lisinathus. AMF was shown to enhance lisianthus growth and yield, especially once AMF was introduced to the growth medium during seeding and to the pit hole during planting. Enhanced growth and yield parameters included flowering stem length and number of flowers. Yield enhancement was recorded both under low and regular Phosphorus conditions. Also, a tendency towards a higher resilience against two pathogenic fungi was recorded following AMF inoculation. Hence, AMF is suggested to be a useful growth amendment for promotion of lisianthus commercial production, and may potentially be applied for additional ornamental crops. Picture taken from Yair station, Arava R&D This study is conducted in collboration with Prof. Yoram Kapulnik from the Volcani Center, Israel, Dr. Eitan Shlomo, and is located in MOP DAROM and inYair station, Arava R&D. 3. Flowering regulation of ornamental crops: Development of growth protocol for Echinops - please see http://www.agri.gov.il/he/people/597.aspx
4. Development of functional genomics tools: microarray hybridization specificity Microarray-hybridization specificity is one of the main effectors of microarray result quality (1). This is especially true for many species of interest, including many important species, for which readymade microarrays are still not available. Studies of these species, using microarrays of related species or strains (i.e., cross-species, cross-strain or cross-population microarray hybridizations), may suffer from reduced specificity (1,2). Previously, we have developed an approach that utilizes the raw, quantification data of microarray hybridization for increase of results specificity (3). Observed differences between scanned image spot characteristics of raw quantification data of high and low specificity hybridizations were found correlative to the phylogenetic distance between the target and reference species and to the level of sequence-similarity of their genes. Based on these results, filtration of raw quantification data was applied and was proved to yield improved biological results (3). We present a new computational tool, ISHY (Increased Specificity of microarray Hybridization), which by image processing means, utilizes the raw, quantification data of microarray hybridization. It uses pre-established (3) and novel spot characteristics, and combines these with gene sequence data for extraction of valid results with enhanced specificity; ISHY has been tested for data of several microarray experiments to explore and promote microarray hybridization specificity. Hybridization specificity may be dissected, by defining four hybridization levels, from the single probe to the microarray platform, and be affected by various effectors of hybridization specificity. Some of the effectors may be better controlled by processing of raw hybridization data, combined with probe sequence data. Based on our findings, the role of microarrays as a tool for high throughput functional genomics will be discussed in view of the emerging era of ultra-fast sequencing of multiple species and strains. This research is conducted in collaboration with Prof. Hanock Czosnek from the Hebrew University, Rehovot, Israel.
Our peer reviewed publications in this subject: Bar-Or C.**, Bar-Eyal M., Gal T.Z.**, Kapulnik Y., Czosnek H. and Koltai H. (2006) Derivation of Species-Specific Hybridization-like Knowledge out of Cross-Species Hybridization Results. BMC Genomics 7: 110. Bar-Or C.**, Czosnek H. and Koltai H. (2007) Cross-species microarray hybridizations: a developing tool for studying diversity. Trends in Genetics 23:200-207. Bar-Or C.**, Novikov E., Reiner A., Czosnek H. and Koltai H. (2007) Utilizing Microarray Spot Characteristics to Improve Cross-Species Hybridization Results. Genomics, 90:636-645.
Koltai H. and Weingarten-Baror C.** (2008). Specificity of DNA microarray hybridization: characterization, effectors and approaches for data correction. Nucleic Acids Research, 36:2395-2405. Lab Members
Dr. Einav Mayzlish-Gati, post doctoral fellow Dr. Mor Grinberg-Yaari Yulia Kaplan, Research Engineer Niv Faig, MSc student Maja Cohen, MSc student Dickla Koren, undergraduate student Yoni Salami, undergraduate student
Past Lab members Dr. Chatalie Bahattacharya, post doctoral fellow Hadas Vrotzlavsky, MSc student Doron Meir, MSc student Einat Eliyahu, MSc student Anat Mosheyov, PhD student Hagit Shealtiel Dr. Sivarama Lekalla, post doctoral fellow Igor Kolotilin, Ph.D., PostDoc Carmiya Bar-Or, Ph.D., Ph.D. student Zohar Freiman, MSc student Tali Z. Gal, Ph.D.Post-doctoral fellow Elitsur Aussenberg, MSc Galit Weil, MSc student Vishal Somvanshi, Ph.D., Post-doctoral fellow Amir Butbul, Undergraduate student Anton Khankin, Undergraduate student
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Recent Publications Koltai, H. and Volpin, H. (2003). Agricultural genomics: an approach to plant protection. Eur. J. Plant Pathol. 109: 101-108. Gal, T.Z.**, Glazer I. and Koltai, H. (2003). Differential Gene expression during desiccation stress in Steinernema feltiae IS6.J. Parasitol. 89: 761-766. Gal, T.Z.**, Glazer I. and Koltai, H. (2004). An LEA3 family member is involved in survival of C. elegans during exposure to dehydration stress.FEBS letters 577: 21-26 Bar-Or C.**, Kapulnik Y. and Koltai H. (2005).A broad characterization of the transcriptional profile of the tomato response to the plant parasitic root knot nematode. Eur. J. Plant Pathol. 111: 181-192 Gal T.Z.**, Glazer I., Sherman A. and Koltai H. (2005). Protein interaction of Nucleosome Assembly Protein-1 and Casein Kinase 2 during desiccation response in the insect-killing nematode Steinernema feltiae IS-6. J. Parasitol. 91: 691-693 Gal T.Z.**, Glazer I., and Koltai H. (2005).Worms in stress: responding to the post genomics era.Mol. Biochem. Parasitol. 143:1-5 Shani Z., Dekel M., Roiz L., Horowitz M., Kolosovski N., Lapidot S., Alkan S., Koltai H., Tsabary G., Goren R., Shoseyov O. (2006). Expression of endo-1,4-beta-glucanase (cel1) in Arabidopsis thaliana is associated with plant growth, xylem development and cell wall thickening. Plant Cell Rep. 25: 1067-1074. Gal T.Z.**, Aussenberg E.R.**, Bordman S., Kapulnik Y., and Koltai H. (2006).
Expression of a plant expansin is necessary for completion of the root knot nematode life cycle. Planta 4:1-8 Bar-Or C.**, Bar-Eyal M., Gal T.Z.**, Kapulnik Y., Czosnek H. and Koltai H. (2006) Derivation of Species-Specific Hybridization-like Knowledge out of Cross-Species Hybridization Results. BMC Genomics 7: 110. Bar-Or C.**, Czosnek H. and Koltai H. (2007) Cross-species microarray hybridizations: a developing tool for studying diversity.Trends in Genetics 23:200-207. Bar-Or C.**, Novikov E., Reiner A., Czosnek H. and Koltai H. (2007)
Utilizing Microarray Spot Characteristics to Improve Cross-Species Hybridization Results Genomics, 90:636-645. Kolotilin I, Koltai H, Tadmor Y, Bar-Or C, Reuveni M, Meir A, Nahon S, Shlomo H, Chen L, Levin I. (2007) Transcriptional profiling of high pigment-2dg tomato mutant links early fruit plastid biogenesis with its overproduction of phytonutrients. Plant Physiology 145:389-401. Somvanshi V.S.**, Koltai H. and Glazer I. (2008). Expression of different desiccation-tolerance related genes in various species of entomopathogenic nematodes. Molecular and Biochemical Parasitology, 158:65-71. Koltai H. and Weingarten-Baror C.** (2008). Specificity of DNA microarray hybridization: characterization, effectors and approaches for data correction. Nucleic Acids Research, 36:2395-2405. Dermatsev V., Weingarten-Baror C., Resnick N., Gadkar V., Wininger S., Kolotilin I., Mayzlish-Gati E., Zilberstein A., Koltai H. and Kapulnik Y. (2009). Microarray analysis and functional tests suggest expansins' involvement in the early stages of AM fungus Glomus intraradices symbiosis on tomato (Solanum lycopersicum). Molecular Plant Pathology, 11:121 - 135. Levin M., Resnick N., Rosianskey Y., Kolotilin I., Wininger S., Lemcoff H., Cohen S., Galili G., Koltai H. and Kapulnik Y. (2009). Transcriptional profiling of Arabidopsis thaliana plants' response to low relative humidity suggests a shoot-root communication. Plant Science, 177: 450-459 Koltai H., Dor E., Hershenhorn J., Joel D.M., Weininger S., Lekalla S., Shealtiel H., Bahattacharya C., Eliahu E., Resnick N., Barg R. and Kapulnik Y. (2009). Strigolactones' Effect on Root Growth and Root-Hair Elongation may be Mediated by Auxin-Efflux Carriers. Journal of Plant Growth Regulation, 29:129-136. Dor E., Alperin B., Wininger S., Ben-Dor B., Somvanshi V.S., Koltai H., Kapulnik Y. and Hershenhorn J. (2009).Characterization of a novel tomato mutant resistant to Orobanche and Phelipanche spp. weedy parasites. Euphytica, 171: 371-380
Meir D.**, Pivonia S., Levita R., Dori I., Ganot L., Meir S., Salim S., Resnick N., Wininger S., Shlomo E. and Koltai H. (2010). Application of Mycorrhizae to Ornamental Horticultural Crops: Lisianthus (Eustoma grandiflorum) as a Test Case. Spanish Journal of Agriculture Research, 8: 85-810 Bar-Akiva A., Ovadia R., Rogachev I., Bar-Or C., Bar E., Freiman Z., Nissim-Levi A., Gollop N., Lewinsohn E., Aharoni A., Weiss D., Koltai H. and Oren-Shamir M. (2010). Metabolic networking in Brunfelsia calycina petals after flower opening. Journal of Experimental Botany, 61: 1393-1403 Koltai H., LekKala S.P., Bahattacharya C., Mayzlish-Gati E., Resnick N., Wininger S., Dor E., Yoneyama K., Yoneyama K., Hershenhorn J., Joel D.M. and Kapulnik Y. (2010). A Tomato Strigolactone-Impaired Mutant Displays Aberrant Shoot Morphology and Plant Interactions. Journal of Experimental Botany, 61: 1739-1749 Mayzlish-Gati E., LekKala S.P., Resnick N., Wininger S., Bhattacharya C., Lemcoff J.H., Kapulnik Y., Koltai H. (2010). Strigolactones are positive regulators of light-harvesting genes in tomato. Journal of Experimental Botany, 61: 3129-3136 Kapulnik Y., Delaux P-M, Resnick N, Mayzlish-Gati E, Wininger S, Bhattacharya C, Séjalon-Delmas N, Combier J-P, Bécard G, Belausov E, Beeckman T, Dor E, Hershenhorn J, Koltai H. (2010) Strigolactones affect lateral root formation and root hair elongation in Arabidopsis. Planta, in press. Books, book chapters and invited reviews 4c. Volpin H, Koltai H. (2004).
Postgenomic Challenges in Plant Bioinformatics.
In: The New Avenues in Bioinformatics (eds., J. Seebach and E.Rubin). Pp. 135-143. Kluwer Academic Publishers, Dordrecht. 5b. Koltai H., Meir D., Resnik N., Shlomo E., Wininger S. and Ben-Dor B. (2008)
Application of Mycorrhiza to Ornamental Horticulture Crops. In: Mycorrhiza Works (eds. Y. Kapulnik and F. Feldman). Pp. 39-45. DFG Selbstverlag, Braunschweig, Germany. 6a. Koltai H. and Bar-Or C. (2008).
Specificity of Oligonucleotide Microarray Hybridization: Effectors and Their Effects. In: Oligonucleotide Array Sequence Analysis (ed, F. Columbus). Pp. 15-24. NOVA Science Publishers, hauppauge, New York. 7b. Kapulnik Y. and Koltai H. (2009)
Effect of Arbuscular Mycorrhiza Symbiosis on Enhancement of Tolerance to Abiotic Stresses. In: Defensive Mutualism in Microbial Symbiosis (eds., J. White and M. Torres). Pp. 217-234. Taylor & Francis Group, LLC, Boca Raton, FL, USA. 8a. Koltai H. (2009)
Genomics and Genetic improvement of Entomopathogenic Nematodes.
Molecular Approaches and Techniques for the Study of Insect Pathogens. In: Genomics and Genetic improvement of Entomopathogenic Nematodes (eds., P.S. Stock, Boemare N., I. Glazer and J. Vandenberg). Pp.346-364. CABI Publishing, Wallingford, Oxfordshire, UK. 9b. Koltai H., Gadkar V. and Kapulnik Y. (2009).
Biochemical and Practical Views of Arbuscular Mycorrhizal Fungus-Host Association in Horticultural Crops. In: Horticultural Reviewes, (ed. J. Janick), John Wiley & Sons, Inc., in press. 10b. Koltai H. and Kapulnik Y. (2009).
Arbuscular mycorrhiza symbiosis under stress conditions: Benefits and costs. In: Cellular Origin, Life in Extreme Habitats and Astrobiology, Volume: Symbiosis and Stress (ed. J. Seckbach), in press. 11b. Koltai H. and Kapulnik Y. (2010). Strigolactones as mediators of plant growth responses to environmental conditions. Plant Signaling and Behavior, in press.
**a student or post-doc under my supervision Teaching Functional Genomics in the service of agriculture http://www3.huji.ac.il/htbin/course/shnaton13/2007/71994
Graduate course at the Hebrew University, Faculty of Agricultural, Food and Environmental Quality Sciences
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