Abstract
Elevated atmospheric CO2 concentration
(eCO2) reduces nitrogen (N) content in rice plants and
stimulates tillering. However, these are contradictory to the general
consensus that reduced N would constrain rice tillering. To resolve
this, we detected N distribution in organs and transcriptomic changes of
different organs after subjected to eCO2 in combination
with different N application rates. Our results indicated that
eCO2 promoted rice tillers more under higher N supply
conditions, and confirmed that N availability constrained tillering in
the early growth stage. Despite N content declined in the leaf and
sheath of rice exposed to eCO2, the new-born tillers had
a stable or higher N content compared to those under ambient
CO2. Apparently the redistribution of N within the plantper se was a critical adaptation strategy to eCO2condition. Transcriptomic analysis revealed that eCO2introduced less extensive alteration of gene expression than N
application. Most importantly, the expression levels of multiple
N-related transporters and receptors were differentially regulated,
suggesting that multiple genes were involved in sensing the N signal and
transporting N metabolites in adapting to eCO2. The
redistribution of N in different organs could be a universal adaptation
strategy of terrestrial plants to eCO2.
Keywords: atmospheric CO2, rice, tiller, nitrogen,
distribution, gene expression.