3.5 N transporters and glutamate receptors were differentially
altered in the leaf and
SAM
Since the N distribution showed dramatic change, we specifically
screened for the N metabolism-related gene expression in the
transcriptome profile. Of the 210 N-related genes, 164 had expression
(FPKM>0.1). Among them, 158 genes were significantly
impacted by the tissue type, 109 genes were affected by N application
rate, and 94 were altered by [CO2] (Table S2).
Apparently, eCO2 exerted a less influential effect to
this specific category of genes than the N application. Further
ascribing the putative functions of those being significantly affected
by [CO2] had revealed that 20 of the 94 (21.3%)
were glutamate receptors and nitrate or ammonium transporters. In
contrast, only seven of 70 (10%) CO2 non-responsive
genes belonged to these groups. It seems that more N metabolite
receptors and transporters were specifically altered by
eCO2, suggesting that N redistribution/reallocation may
become more active under the eCO2. Among them, nine genes displayed
contrasting induction and suppression changes between the leaf and SAM
(Fig. 5). They were putative major facilitator family transporter
(NRT2.3a/b, LOC_Os01g50820, Fig. 5A), ammonium transporters
(LOC_Os01g61510, LOC_Os02g34580, and LOC_Os03g62200, Fig. 5B-D), high
affinity nitrate transporter (LOC_Os04g40410, Fig. 5E) and peptide
transporter PTR2 (NRT1.1a/b, LOC_Os10g40600, Fig. 5F). The others were
all putative glutamate receptors (LOC_Os06g08910, LOC_Os09g26144, and
LOC_Os09g26160, Fig. 5G-H). These genes were likely the critical
contributor to the change of N distribution among organs in the
eCO2 adaptation process in rice plant.