Elevated atmospheric CO2 concentration triggers redistribution of
nitrogen to promote tillering in rice
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 plant per se was a critical adaptation strategy to eCO2
condition. Transcriptomic analysis revealed that eCO2 introduced 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.