Co-Authors:
Zhang, Z., Department of Postharvest Science of Fresh Produce, ARO, The Volcani Center, P.O. Box 6, Bet-Dagan, 50250, Israel, College of Horticulture, South China Agricultural University, 510642 Guangzhou, China
Friedman, H., Department of Postharvest Science of Fresh Produce, ARO, The Volcani Center, P.O. Box 6, Bet-Dagan, 50250, Israel
Meir, S., Department of Postharvest Science of Fresh Produce, ARO, The Volcani Center, P.O. Box 6, Bet-Dagan, 50250, Israel
Rosenberger, I., Department of Postharvest Science of Fresh Produce, ARO, The Volcani Center, P.O. Box 6, Bet-Dagan, 50250, Israel
Halevy, A.H., The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, 76100, Israel
Philosoph-Hadas, S., Department of Postharvest Science of Fresh Produce, ARO, The Volcani Center, P.O. Box 6, Bet-Dagan, 50250, Israel
Abstract:
The microtubule reorientation during the gravitropic bending of cut snapdragon (Antirrhinum majus L.) spikes was investigated. Using indirect immunofluorescence methods, we examined changes in microtubule orientation in the cortex, endodermis and pith tissues of the shoot bending zone, in response to gravistimulation. Our results show that dense microtubule arrays were visible throughout the cortical, endodermal and pith shoot tissues, and that the transverse orientation of the microtubules (perpendicular to the growth axis) was specifically associated with the shoot growing bending zone. Microtubules showed gravity-induced kinetics of changes in their orientation, which occurred only in the upper stem flank and preceded shoot bending. While this observation, that the gravity-induced microtubule orientation precedes bending, was previously reported only in special above-ground organs such as coleoptiles and hypocotyls, our present study is the first to show that such patterns of change occur in mature flowering shoots. These changes were exhibited first in the upper flank of the cortex and then in the upper flank of the endodermis. No changes in microtubule orientation were observed in the cortex or endodermis tissues of the lower flanks or in the pith, suggesting that these tissues continue to grow during shoot gravistimulation. Our results imply that microtubules may be involved in growth cessation of the upper shoot flank occurring during the gravitropic bending of snapdragon cut spikes. © 2007 Elsevier GmbH. All rights reserved.
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