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Abstract Detail


Oxidative Stress

Rivero, Rosa M [1], Mitler, Ron [2], Sakakibara, Hitoshi [3], Gepstein, Shimon [4], Gepstein, Amira [5], Blumwald, Eduardo [6].

Drought tolerance induced by the autoregulated biosynthesis of cytokinins.

The autoregulated biosynthesis of cytokinins, mediated by the expression of a isopentyltransferase (IPT) gene driven by a an inducible early-senescence/late maturation promoter (SARK, senescence-associated receptor kinase), resulted in the remarkable drought tolerance of transgenic tobacco plants. The transgenic plants displayed vigorous growth after a severe drought (18 days without watering). The transgenic plants retained photosynthetic activity during drought and did not show chlorophyll degradation. After rewatering (2 weeks), the plants recovered photosynthetic activity and active growth. Our results showed that plants expressing SARK::IPT, cytokinins were synthesized in the whole plant and transported to the bottom leaves. cDNA macroarrays filters containing stress-related genes were used to assess the effects of IPT on the expression of these genes in the transgenic plants. Many genes were upregulated as compared to the WT plants. Most of these upregulated genes are associated with desiccation, oxidative metabolism, photosynthesis and sugar metabolism. The activity of a large number of enzymes associated with antioxidant production together with photosynthetic activities and sugar production correlated with the gene expression changes. Our results suggest that autoregulated biosynthesis of cytokinins, enhances the production of antioxidants during drought, contributing to protect the photosynthetic machinery, contributing to enhanced stress tolerance and improved yields in the transgenic plants. In addition, transgenic plants displayed vigorous growth when watered with 30% of the amount of water used under operational greenhouse practices with a relatively low yield penalty, suggesting a much improved water use efficiency.


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1 - University of California, Davis, Plant Sciences, One Shields Ave, University Extension Center, Mail Stop 5, Davis, CA, 95616, USA
2 - University of Nevada, Reno, Biochemistry
3 - RIKEN, Yokohama, Kanagawa, JAPAN, Plant Science Center
4 - Technion Institute, ISRAEL, Biology
5 - Technion Israel Inst Technol, PLant Biology, Technion Israel Inst Technol, Haifa, 32000, Israel
6 - University of California, Davis, Plant Sciences

Keywords:
drought and cytokinins.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P06003
Abstract ID:128


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