Details

Autor(en) / Beteiligte

• Banks, F.M
• Driscoll, S.P
• Parry, M.A.J
• Lawlor, D.W
• Knight, J.S
• Gray, J.C
• Paul, M.J

Titel

Decrease in phosphoribulokinase activity by antisense RNA in transgenic tobacco. Relationship between photosynthesis, growth, and allocation at different nitrogen levels

Ist Teil von

• Plant physiology (Bethesda), 1999-03, Vol.119 (3), p.1125-1136

Ort / Verlag

Rockville, MD: American Society of Plant Physiologists

Erscheinungsjahr

1999

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• To study the direct effects of photosynthesis on allocation of biomass by altering photosynthesis without altering leaf N or nitrate content, phosphoribulokinase (PRK) activity was decreased in transgenic tobacco (Nicotiana tabacum L.) with an inverted tobacco PRK cDNA and plants were grown at different N levels (0.4 and 5 mM NH(4)NO(3)). The activation state of PRK increased as the amount of enzyme was decreased genetically at both levels of N. At high N a 94% decrease in PRK activity had only a small effect (20%) on photosynthesis and growth. At low N a 94% decrease in PRK activity had a greater effect on leaf photosynthesis (decreased by up to 50%) and whole-plant photosynthesis (decreased by up to 35%) than at high N. These plants were up to 35% smaller than plants with higher PRK activities because they had less structural dry matter and less starch, which was decreased by 3- to 4-fold, but still accumulated to 24% to 31% of dry weight; young leaves contained more starch than older leaves in older plants. Leaves had a higher ion and water content, and specific leaf area was higher, but allocation between shoot and root was unaltered. In conclusion, low N in addition to a 94% decrease in PRK by antisense reduces the activity of PRK sufficient to diminish photosynthesis, which limits biomass production under conditions normally considered sink limited.