Transgenic, non-isoprene emitting poplars don’t like it hot
| Autor: | Barbara Ehlting, Martina Bauerfeind, Katja Behnke, Markus Teuber, Jörg Bohlmann, Andrea Polle, Jörg-Peter Schnitzler, Robert Hänsch, Sandrine Louis |
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| Rok vydání: | 2007 |
| Předmět: |
0106 biological sciences
chemistry.chemical_classification 0303 health sciences Non-photochemical quenching Cell Biology Plant Science Isoprene synthase Biology Photosynthesis 01 natural sciences Zeaxanthin 03 medical and health sciences chemistry.chemical_compound chemistry Biochemistry 13. Climate action Chlorophyll Xanthophyll Genetics biology.protein Biophysics Chlorophyll fluorescence Isoprene 030304 developmental biology 010606 plant biology & botany |
| Zdroj: | The Plant Journal. 51:485-499 |
| ISSN: | 1365-313X 0960-7412 |
| Popis: | The physiological role of isoprene emission in plants is a matter of much debate. One of the most widely propagated hypotheses suggests a function of isoprene in the protection of leaf physiological processes against thermal and oxidative stress. To test this hypothesis, we developed transgenic Grey poplar (Populusxcanescens) plants in which gene expression of isoprene synthase (ISPS) was either silenced by RNA interference (RNAi) or upregulated by over-expression of the ISPS gene. Despite increased ISPS mRNA levels, we did not observe consistent increases in isoprene emission in the over-expressing lines, indicating post-transcriptional control of ISPS by co-suppression. In the RNAi lines, levels of isoprene emission were effectively suppressed to virtually zero. Transgenic plants were subjected to temperature stress with three transient heat phases of 38-40 degrees C, each followed by phases of recovery at 30 degrees C. Parallel measurements of gas exchange, chlorophyll fluorescence and isoprene emission provided new insights into the physiological link between isoprene and enhanced temperature tolerance. Transgenic non-isoprene-emitting poplars showed reduced rates of net assimilation and photosynthetic electron transport during heat stress, but not in the absence of stress. The decrease in the efficiency of photochemistry was inversely correlated with the increase in heat dissipation of absorbed light energy, measured as NPQ (non-photochemical quenching). Isoprene-repressed poplars also displayed an increased formation of the xanthophyll cycle pigment zeaxanthin in the absence of stress, which can cause increased NPQ or may indicate an increased requirement for antioxidants. In conclusion, using a molecular genetic approach, we show that down-regulation of isoprene emission affects thermotolerance of photosynthesis and induces increased energy dissipation by NPQ pathways. |
| Databáze: | OpenAIRE |
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