Detail Ecological and evolutionary aspects of the emission of isoprene from land plants Bibliografi Author: Hanson, David Thomas ; Sharkey, Thomas D. (Advisor); Graham, Linda E. (Advisor) Topik: BIOLOGY; PLANT PHYSIOLOGY|BIOLOGY; BOTANY Bahasa: (EN )    ISBN: 0-599-64117-7     Penerbit: THE UNIVERSITY OF WISCONSIN - MADISON     Tahun Terbit: 1999     Jenis: Theses - Dissertation Fulltext: 9956195.pdf (0.0B; 0 download) Abstract Isoprene is a five-carbon hydrocarbon emitted from the leaves of plants. The emission of isoprene is light-dependent and temperature sensitive. Plants lose a large fraction of carbon as isoprene, however, the emission of isoprene increases the thermotolerance of photosynthesis. Isoprene emission from plants also has a large impact on atmospheric chemistry. Since isoprene increases the thermotolerance of photosynthesis, I hypothesized that warm growth temperatures and high light levels would increase the capacity for isoprene emission. I compared the capacity for isoprene emission with the expression of other thermotolerance mechanisms under two growth temperatures and two growth light intensities. Capacity was determined by measuring isoprene emission rates under standard assay conditions of 30°C and 1000 μmol photons m−2 s−1. Only the capacity for isoprene emission increased under high temperature and high light. Xanthophyll cycle intermediates increased in high light, but not high temperature and the chloroplast heat shock protein was not expressed in any of the conditions. Models that predict the flux of isoprene into the atmosphere assume that the capacity for isoprene emission is constant. Since I found that the capacity for isoprene emission varied with growth conditions, I tested the rate at which it changes. Acclimation to new growth temperatures occurred within a day. Acclimation to new light was more complicated. There was a short-term (min) acclimation of isoprene emission to assay light level and a small, long-term (4–6 day) acclimation to growth light level. Current models of isoprene emission need to be altered to reflect changes in the capacity for isoprene emission. Isoprene emission is most beneficial to plants experiencing rapid temperature fluctuation so it may be more beneficial to terrestrial plants than aquatic plants. I surveyed early divergent land plants for isoprene emission and compared the frequency of emitting species with published surveys of other photosynthetic organisms. I found that light-dependent isoprene emission was absent in algae and probably evolved in mosses, then was repeatedly lost in higher plants. I also found that isoprene emission increased the thermotolerance of photosynthesis in moss. Therefore, isoprene emission may have been beneficial for the radiation of early plants on land. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Lihat Sejarah Pengadaan  Konversi Metadata   Kembali

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