Growth at elevated CO2 concentrations leads to modified profiles of secondary metabolites in tobacco cv. SamsunNN and to increased resistance against infection with potato virus Y.
The effect of elevated CO2 concentrations on the levels of secondary metabolites was investigated in tobacco plants grown under two nitrogen supply (5 and 8 mM NH4NO3) and CO2 conditions (350 and 1000 p.p.m.) each. High CO2 resulted in a dramatic increase of phenylpropanoids in the leaves, including the major carbon-rich compound chlorogenic acid (CGA) and the coumarins scopolin and scopoletin at both nitrogen fertilizations. This was accompanied by increased PAL activity in leaves and roots, which was even higher at the lower nitrogen supply. Hardly any change was observed for the structural phenolic polymer lignin and the sesquiterpenoid capsidiol. In contrast, elevated CO2 led to clearly decreased levels of the main nitrogen-rich constituent nicotine at the lower N-supply (5 mM NH4NO3) but not when plants were grown at the higher N-supply (8 mM NH4NO3). Inoculation experiments with potato virus Y (PVY) were used to evaluate possible ecological consequences of elevated CO2. The titre of viral coat-protein was markedly reduced in leaves under these conditions at both nitrogen levels. Since PR-gene expression and free salicylic acid (SA) levels remained unchanged at elevated CO2, we suggest that the accumulation of phenylpropanoids, for example, the major compound CGA and the coumarins scopolin and scopoletin may result in an earlier confinement of the virus at high CO2. Based on our results two final conclusions emerge. First, elevated CO2 leads to a shift in secondary metabolite composition that is dependent on the availability of nitrogen. Second, changes in the pool of secondary metabolites have important consequences for plant-pathogen interactions as shown for PVY as a test organism.
Matros
Andrea
A
Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, D-06466 Gatersleben, Germany.
Amme
Steffen
S
Kettig
Barbara
B
Buck-Sorlin
Gerhard H
GH
Sonnewald
Uwe
U
Mock
Hans-Peter
HP
D002244:Carbon / Q000032:analysis; D002245:Carbon Dioxide / Q000378:metabolism*; D007113:Immunity, Innate; D008031:Lignin / Q000032:analysis; D009538:Nicotine / Q000378:metabolism*; D009584:Nitrogen / Q000032:analysis; D010636:Phenols / Q000378:metabolism*; D010650:Phenylalanine Ammonia-Lyase / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000201:enzymology; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology; D017800:Potyvirus / Q000502:physiology*; D020156:Salicylic Acid / Q000032:analysis; D014026:Nicotiana / Q000145:classification / Q000254:growth & development / Q000378:metabolism* / Q000821:virology*
D010636:Phenols; D010940:Plant Proteins; D002245:Carbon Dioxide; D009538:Nicotine; D002244:Carbon; D008031:Lignin; D010650:Phenylalanine Ammonia-Lyase; D009584:Nitrogen; D020156:Salicylic Acid