Alex Lipsky, PhD
Micropropagation of plants (Alstromeria, Calla lily, new cultivsrs of Ornithogalum) for laboratory uses and establishment of propagation protocols for new crops.
Reduction of soft rot caused by Pectobacterium carotovorum in Zandetechia spp. or other geophytes by the use of chemical defense elicitors. To minimize proliferation and destruction caused by the soft rot bacterium we study the application of plant activators, an approach hardly tested in monocot geophytes. These compounds are capable of inducing systemic resistance mechanisms in various plant species against bacterial, viral and fungal plant pathogens. The potential of this approach in monocots was already demonstrated in model plants (mainly grasses, i.e. wheat, oat, rice and maize) where it was establish as highly effective and long lasting compared to dicots. A system based on plant leaf discs or tuber sections was established and calibrated to test virulence and pathogenicity of Pectobacterium strains. The defense elicitors are tested and analyzed in that system. Methyl jasmonate was found to inhibit the bacteria and the development of disease symptoms for up to seven days in the leaf discs assay. BTH was able to reduce disease symptoms however, the resistance was not persistent.
• The lab is also involved in the study of secondary metabolites production and relationship to the plants defense response, during the induced/challeged state. The study involves biochemical and analytical chemistry approaches for the separation, quantification and identification of the induced compounds. Secondary metabolites are studied with special emphasis on antimicrobial activity against Pectobacterium carotovorum. The structure of two induced compounds was established and confirmed as flavonoides C-glycosides of apigenin - swertizin and isovitexin.
• The lab is exploring expression patterns of defense related genes. We study the homologs of several monocot defense-related genes including jasmonic acid-related genes (LOX1, MYB), PR genes (PR1, PR2 ?-1,3 glucanase, PR5, PR10, PR-9 Peroxidase) and phytoalexines related genes (flavonoid o-methyltransferase, chalcone synthase) in the monocot geophytes system.
• The lab uses biotechnology approaches to produce Pecotobacterium resistant Ornithogalum dubium plants. The production of transformed plants expressing the antimicrobial peptide tachyplesin was accomplished with the lab of Dr. Avner Cohen. We have developed a screening protocol for resistance during the regeneration and microporopagation process of the transformed plantlets.
Characterization of Pectobacterium carotovorum isolates from several plant hosts including ornamental geophytes
Our lab founded a collection of bacterial isolates from several plant hosts including ornamental geophytes. We study these isolates with special focus on virulence and specificity. Molecular techniques and bioinformatics approaches were used to analyze the differences among strains. The results reflected a significant distance between Pectobacterium carotovorum subsp. carotovorum isolates from dicots and monocot hosts. The 16S rRNA sequence analysis and AFLP support early genomic divergence within this taxon.
We are also involved in field studies concerned with Pectobacterium transfer and capability to shift between ornamental crops.
List of Publications
1. Yedidia, I., Benhamou, N., Chet, I. 1999. Induction of defense responses in cucumber plants (Cucumis sativus L.) by the biocontrol agent Trichoderma harzianum. App. Environ. Microbiol. 3: 1061-1070
2. Yedidia, I., Benhamou, N., Kapulnik, Y., Chet, I. 2000. Induction and accumulation of PR proteins activity during early stages of roots colonization by the mycoparasite Trichoderma harzianum. Plant Physiol. Biochem. 38: 863-873.
3. Yedidia, I., Srivatka, A., Kapulnik, Y., Chet, I. 2001. Effect of Trichoderma harzianum on uptake of microelements and increased growth response of cucumber plants. Plant Soil. 235:235-242.
4. Yedidia, I., Shoresh, M., Kerem, Z., Kapulnik, Y., Chet, I. 2003. Concomitant induction of systemic resistance to Pseudomonas syringae pv. lachrymans in cucumber by Trichoderma asperellum (T-203) and the accumulation of phytoalexins. Appl. Environ. Microbiol. 69: 7343-7353.
5. Wallerstein, I., Wallerstein, I. S., and Yedidia, I. 2004. Interaction between natural winter daylight conditions and supplementary artificial lightning in the induction of flowering in the longday plant Hypericum indorum. Flowering News Letter. 38: 34-42.
6. Shoresh, M., Yedidia, I., Chet, I. 2005. The involvement of JA/ethylene signaling pathway in the systemic resistance induced in cucumber by Trichoderma asperellum T203. 2005. Phytopathology. 95: 76-84
7. Bing Ma, Michael E. Hibbing, Hye-Sook Kim, Ralph Reedy, Iris Yedidia, Jane Breuer, Jeff Breur, Jeremy Glasner, Nicole T. Perna, Arthur Kelman, and Amy O. Charkowski. 2007. The Host Range and Molecular Phylogenies of the Soft Rot Enterobacterial Genera Pectobacterium and Dickeya. Phytopathology. 97:1150-1163.
7.a. Editor's pick: Phytopathology. 2007. 97: September issue.
8. Luzzatto T, Yishay M, Lipsky A, Ion A, Belausov E, Yedidia I. 2007. Efficient, long-lasting resistance against the soft rot bacterium Pectobacterium carotovorum in calla lily provided by the plant activator methyl jasmonate. Plant Pathology. 56: 692-701.
8.a. Cover page: Plant Pathology. 2007. 56: August issue.
9. Tal Luzzatto, Avner Golan, Moran Yishay, Itshak Bilkis and Iris Yedidia. 2007. Priming of antimicrobial phenolics during induced resistance response towards Pectobacterium carotovorum in the ornamental monocot calla lily. Agricultural and Food Chemistry. 55: 10315-10322
10. Moran Yishay, Saul Burdman, Angel Valverde, Tal Luzzatto, Ron Ophir and Iris Yedidia. 2008. Differential pathogenicity and genetic diversity among Pectobacterium carotovorum subsp. carotovorum isolates from monocot and dicot hosts support early genomic divergence within this taxon. Environmental Microbiology. 10: 2746-2759.
11. Iris Yedidia, Alex Lipsky, Avner Golan, Moran Yishay, Aurel Ion, and Tal Luzzatto. 2008 Polyphenols induction in the defense response of calla lily towards Pectobacterium carotovorum. Acta Horticulture. In press.
12. Iris Yedidia, Ron Ophir, Moran Yishay, Aurel Ion, Tal Luzzatto, Avner Golan, and Saul Burdman. A story of an old battle: Pectobacterium carotovorum and ornamental monocots. Acta Horticulture. In press.
13. A. Cohen, A. Lipsky, T. Arazi, N. Gollop, S. Manulis, A. Ion, R. Stav, D. Sandler-Ziv, C. Fintea and I. Yedidia. Molecular Breeding of Ornithogalum for Erwinia Resistance. Acta Horticulture. In press.
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