Journal Article

Enhanced Cytokinin Synthesis in Tobacco Plants Expressing <i>P<sub>SARK</sub>::IPT</i> Prevents the Degradation of Photosynthetic Protein Complexes During Drought

Rosa M. Rivero, Jacinta Gimeno, Allen Van Deynze, Harkamal Walia and Eduardo Blumwald

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 51, issue 11, pages 1929-1941
Published in print November 2010 | ISSN: 0032-0781
Published online September 2010 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcq143
Enhanced Cytokinin Synthesis in Tobacco Plants Expressing PSARK::IPT Prevents the Degradation of Photosynthetic Protein Complexes During Drought

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

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To identify genes associated with the cytokinin-induced enhanced drought tolerance, we analyzed the transcriptome of wild-type and transgenic tobacco (Nicotiana tabacum ‘SR1’) plants expressing PSARK::IPT (for senescence-associated receptor kinase::isopentenyltransferase) grown under well-watered and prolonged water deficit conditions using the tomato GeneChip. During water deficit, the expression of genes encoding components of the carotenoid pathway leading to ABA biosynthesis was enhanced in the wild-type plants, but repressed in the transgenic plants. On the other hand, transgenic plants displayed higher transcript abundance of genes involved in the brassinosteroid biosynthetic pathways. Several genes coding for proteins associated with Chl synthesis, light reactions, the Calvin–Benson cycle and photorespiration were induced in the transgenic plants. Notably, increased transcript abundance of genes associated with PSII, the cytochrome b6/f complex, PSI, NADH oxidoreductase and the ATP complex was found in the PSARK::IPT plants. The increased transcript abundance was assessed by quantitative PCR and the increased protein levels were confirmed by Western blots. Our results indicated that while the photosynthetic apparatus in the wild-type plants was degraded, photosynthesis in the transgenic plants was not affected and photosynthetic proteins were not degraded. During water deficit, wild-type plants displayed a significant reduction in electron transfer and photochemical quenching, with a marked increase in non-photochemical quenching, suggesting a decrease in energy transfer to the PSII core complexes and an increase in cyclic electron transfer reactions.

Keywords: Cytokinins; Drought; IPT; Nicotiana tabacum ‘SR1’; Photosynthesis; Water deficit

Journal Article.  7648 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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