Morgan, J.A. and Brown, R.H. (1979) Photosynthesis in grass species differing in carbon dioxide fixation pathways. 2. A search for species with intermediate gas exchange and anatomical characteristics. Plant Physiology, 64 (2). pp. 257-262.
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Abstract
33 grass spp. were examined in 2 experiments in an attempt to locate plants with photosynthetic responses to O2, CO2 compensation conc. and leaf anatomy intermediate to those of C3 and C4 plants; those examined included 7 from the Laxa group in the genus Panicum, one of which, P. milioides, had been reported earlier to have intermediate characteristics. The species with O2- sensitive photosynthesis typical of C3 plants showed 37% increase in apparent photosynthesis at 2% O2 compared with 21% O2 at 25 deg C and 335 mu l/l CO2, whereas in Panicum milioides, P. schenckii and P. decipiens, members of the Laxa group, increases ranged from 25 to 30%. The remainder of the spp. did not respond to O2. Spp. with O2 responses characteristic of C3 plants exhibited CO2 compensation conc. of 44 mu l/l or higher at 21% O2 and 25 deg to 27.5 deg , and spp. characterized as O2 insensitive had values of 6 mu l/l or less. The CO2 compensation conc. ( GAMMA ) values of P. milioides, P. schenckii and P. decipiens ranged from 10.3 to 23.3 mu l/l. Other spp. of the Laxa group exhibited O2 response and GAMMA values of either C3 (P. laxum, P. hylaeicum and P. rivulare) or C4 (P. prionitis) plants. Leaves of spp. with O2 response and CO2 compensation values typical of C3 plants had poorly developed or nearly empty bundle sheath cells, and much larger distances and mesophyll cell numbers between veins than did the O2-insensitive ones. Vein spacings in P. milioides, P. schenckii and P. decipiens ranged from 0.18 to 0.28 mm and mesophyll cell number between veins from 5.2 to 7.8. While these vein spacings were closer than those of most C3 grasses, 2 O2-sensitive spp. of Dactylis had vein spacings similar to the Panicum spp., and veins in Glyceria striata, another O2-sensitive plant, were separated by only 4 mesophyll cells and 0.12 mm. Bundle sheath cells of the 3 intermediate Panicum spp. contained greater quantities of organelles than were typical for C3 grasses
| Item Type: | Article |
|---|---|
| Author Affiliation: | Department of Agronomy, Georgia University, Athens, GA 30602, USA |
| Subjects: | Plant Physiology and Biochemistry > Plant Physiology Plant Physiology and Biochemistry > Biochemistry |
| Divisions: | Other Crops |
| Depositing User: | Ms K Syamalamba |
| Date Deposited: | 08 May 2012 10:55 |
| Last Modified: | 08 May 2012 10:55 |
| Official URL: | http://dx.doi.org/10.1104/pp.64.2.257 |
| URI: | http://eprints.icrisat.ac.in/id/eprint/5182 |
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