Effect of CO2 enrichment and increased nitrogen supply on the induction of sunflower (Helianthus annuus L.) primary leaf senescence
2016
Canales, F.J. | de la Haba, P. | Barrientos, E. | Agüera, E.
A study was made of the effect of atmospheric CO₂ enrichment and increased nitrogen availability on primary leaf senescence in sunflower (Helianthus annuus L.). First, markers normally used for monitoring leaf development (dry weight, leaf surface area, protein content, photosynthetic pigment levels, CO₂ fixation rate, changes in the enzymes involved in nitrogen metabolism, and plant-tissue oxidative status) were measured in plants grown for 42 days under ambient (400 µL L⁻¹) or enriched CO₂ conditions (800 µL L⁻¹), and with two different levels of nitrate supply (10 mM and 25 mM). Second, two-dimensional electrophoresis (2-DE) was used to compare primary-leaf protein profiles (16 and 42 days) in sunflowers grown under ambient or enriched CO₂ conditions with elevated nitrate supply. Plants grown under enriched CO₂ conditions and with high nitrogen supply displayed faster growth, a higher CO₂ fixation rate, and increased activity by antioxidative and nitrogen-metabolism-related enzymes than those grown under elevated CO₂ with low nitrogen supply. These findings indicate that CO₂ enrichment and increased nitrate availability slow down the induction of senescence, suggesting that senescence may be directly related to leaf C/N ratio. These results enhance our understanding of the sunflower’s response to increased atmospheric CO₂ levels, one of the environmental factors favoring climate change.
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