Effective carbon partitioning driven by exotic phloem-specific regulatory elements fused to the Arabidopsis thaliana AtSUC2 sucrose-proton symporter gene

Table 3 Exudation and retention of 14C in leaves after photosynthetic labeling

Plant Line	Percent Cumulative Exudation					Soluble Residual	Insoluble Residual
	0 hrs	2 hrs	4 hrs	9 hrs	20 hrs
WT^a	0.0 ± 0.0^b	20.8 ± 4.1	36.7 ± 6.5	56.4 ± 6.2	70.1 ± 6.2	19.4 ± 4.9	10.5 ± 2.2
SUC2p (1039)^a	0.1 ± 0.2	16.6 ± 5.3	31.4 ± 8.7	52.8 ± 6.5	66.5 ± 5.7	21.4 ± 1.8	12.1 ± 5.3
CoYMVp (1070)	0.5 ± 0.4^c	14.3 ± 3.1^c	27.8 ± 6.1^c	51.4 ± 4.6	67.9 ± 4.2	19.9 ± 1.3	12.2 ± 3.0
RolCp (1133)	0.0 ± 0.0	15.1 ± 4.4^c	26.8 ± 7.1^c	47.0 ± 4.2^c	62.6 ± 2.6^c	24.4 ± 1.6^c	12.9 ± 1.9

Percentage of ¹⁴C-photosynthate exuded from cut petioles and retained in the leaf 20 hours after photosynthetic labeling with ¹⁴CO₂. Four mature leaves from each of four replicate plants were arranged in a 24 well microtiter plate and photosynthetically labeled for 20 minutes with 14CO2 in a sealed chamber three feet below a 400 W metal halide bulb. Exudation into 15 mM EDTA proceeded for 20 hours under ambient room light, and the EDTA solutions were changed and counted at the indicated time points.
^a [25]
^b Average ± Std. Dev., n = 4
^c Student's T-test, p ≤ 0.1 relative to WT.

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