Table 1.

Genes responding to rising pCO₂ and involved in pigment synthesis, photosystems, C metabolism, C storage, N assimilation, and stress response.

Gene or IPF number	Gene function category	Annotation	Log2 values at different time points (h)
			0.75	2	4	8	24	72	336
PIGMENT GENES (3 OF THE 33)
cpcI	8	Phycocyanin synthesis	ns	ns	ns	ns	ns	0.93	0.92
crtO	2	Beta-carotene synthesis	ns	ns	ns	1.05	ns	ns	ns
1003	16	Beta-carotene synthesis	ns	0.94	0.99	ns	ns	ns	ns
PHOTOSYSTEM GENES (0 OF THE 31)
C METABOLISM GENES (2 OF THE 38)
zwf	6	Glycolysis and oxidative pentose	ns	ns	ns	0.90	ns	ns	ns
icd	6	Phosphate pathway citric acid cycle	ns	ns	ns	0.95	ns	ns	ns
C STORAGE GENES (4 OF THE 15)
phaC	5	Polyhydroxyalkanoate storage	ns	ns	ns	1.13	ns	ns	ns
phaA	5	Polyhydroxyalkanoate storage	ns	ns	ns	1.18	ns	ns	ns
phaB	5	Polyhydroxyalkanoate storage	ns	ns	ns	1.15	ns	ns	ns
phaE	5	Polyhydroxyalkanoate storage	ns	ns	0.91	1.20	ns	ns	ns
N ASSIMILATION GENES (9 OF THE 29)
glnN	1	GS/GOGAT	ns	1.24	1.51	0.94	ns	1.16	1.45
gltB	1	GS/GOGAT	ns	ns	ns	0.91	ns	ns	ns
nrtA	14	Nitrate transport	ns	1.08	1.02	ns	ns	ns	ns
nrtB	14	Nitrate transport	ns	0.99	ns	ns	ns	ns	ns
ntcB	1	Nitrate transport	ns	1.05	0.90	ns	ns	ns	ns
nirA	1	Nitrite reductase	ns	0.92	ns	ns	ns	ns	ns
1263	14	Ammonium transport	ns	1.15	1.44	0.97	ns	ns	ns
urtA	14	Urea transport	ns	ns	0.94	ns	ns	ns	ns
5363	14	Urea transport	ns	0.91	1.01	ns	ns	ns	ns
STRESS-RELATED GENES (8 OF THE 22)
flv2	15	Flavoprotein	ns	ns	−1.81	ns	ns	ns	ns
flv4	15	Flavoprotein	ns	ns	−2.31	ns	ns	ns	ns
isiA	8	Chlorophyll-binding	ns	ns	−1.47	−1.33	ns	ns	−1.76
isiB	8	Flavodoxin	ns	ns	−1.03	ns	ns	ns	ns
sigB	12	Sigma factor	ns	ns	ns	ns	ns	−1.16	ns
sigE	12	Sigma factor	ns	ns	ns	0.94	ns	ns	ns
sigH	12	Sigma factor	ns	ns	−1.30	−1.36	−1.59	−2.49	−2.62

Log2 values quantify gene expression at the given time point (after increasing the pCO₂) with respect to gene expression at t = 0 (just before increasing the pCO₂). Only the responsive genes are shown; the complete data set including all non-responsive genes is provided in Supplementary Table 4. IPF numbers are the locus tags of Microcystis PCC 7806 in the EMBL database (AM778843–AM778958). ns, not significant; GS/GOGAT, glutamine synthetase/glutamine-2-oxoglutarate amidotransferase; Gene function categories (CyanoBase), (1) amino acid biosynthesis; (2) biosynthesis of cofactors, prosthetic groups, and carriers; (5) central intermediary metabolism; (6) energy metabolism; (8) photosynthesis, and respiration; (12) transcription; (14) transport and binding proteins; (15) other categories; (16) hypothetical.