Table 2.

The levels of total, inorganic, organic nitrogen and RNA in top leaves of wild-type (Wt) and SO RNA interference mutants (Ri) plants under normal growth conditions (0 day) or after being exposed to eleven days of extended dark stress (11 day).

Total, Organic and Inorganic (Nitrate and Ammonium) Nitrogen in the Top Leaves.
µmol·g−1 Fw		Wt				SO Ri
		0 day		11 day		0 day		11 day
Inorganic N	N (nitrate)	65.4 ± 5.6 Ba		98.8 ± 13.2 Ab		44.8 ± 3.7 Bb		133.2 ± 8.4 Aa
	N (ammonium)	10.3 ± 0.9 Bb		42.3 ± 12.1 Ab		14.8 ± 2.7 Ba		73.4 ± 10.2 Aa
Organic N		346.9 ± 11.5 Aa		327.6 ± 8.0 Aa		325.2 ± 10.5 Aa		259.7 ± 26.7 Bb
Total N		422.5 ± 12.5 Ba		468 ± 6.7 Aa		384.7 ± 12.6 Bb		466.3 ± 37.7 Aa
The levels of nitrate and ammonium in the stem just below the top leaves *
µmol·mL−1 sap		Wt				SO Ri
		0 day		11 day		0 day		11 day
Inorganic N	N (nitrate)	0.7 ± 0.07 Bb		10.0 ± 2.6 Ab		1.4 ± 0.4 Ba		15.7 ± 1.7 Aa
	N (ammonium)	4.3 ± 0.8 Bb		11.4 ± 1.0 Ab		5.0 ± 0.5 Ba		41.4 ± 4.7 Aa
Total RNA in the top leaves **
µg·g−1 Fw	Wt				SO Ri
	0 day	11 day	degraded		0 day		11 day		degraded
RNA	320.0 ± 31.2 Aa	221.9 ± 20.2 Ba	98.1 ± 18.3 b		388.3 ± 18.5 Aa		197.5 ± 24.1 Ba		190.9 ± 15.1 a

* For nitrate determination in the stem xylem sap, exudate was collected from stem topped 1 cm below the top leaves after applying 6.2 bar for 10 min by a pressure chamber, Arimad 2; ** Degraded RNA was calculated as the RNA level in T0 minus the level in T11. The values denoted with different letters are significantly different according to the Turkey-Kramer HSD test (JMP 8.0 software, [37]; p < 0.05, n = 3–10). Different lower case letters indicate differences between SO mutant and wild-type plants within the same treatment. Different upper case letters indicate significant difference within the plant genotypes in response to treatment. The data for SO-compromised plants represent the mean for SO Ri 131 and SO Ri 421 mutants.