Defects in leaf carbohydrate metabolism compromise acclimation to high light and lead to a high chlorophyll fluorescence phenotype in Arabidopsis thaliana

Table 3 Photosynthetic performance as well as pigment contents of Col-0 and adg1-1/tpt-2 plants grown on agar plates containing 1/2 strength MS medium (A) or 1/2 MS supplemented with 50 mM Suc (B) under HL-conditions

Plant line	F_v/F_mratio	ΦPSII	Chl content (mg·g^-1 fw)	Chl *a/b*ratio	Carotenoid content (μg·g^-1 fw)
A Plants grown on 1/2 MS
Col-0	0.76 ± 0.01	0.34 ± 0.03	1.43 ± 0.10	3.02 ± 0.14	51.3 ± 4.0
adg1-1/tpt-2	0.35 ± 0.10 ^b	0.06 ± 0.05 ^a	0.85 ± 0.14 ^b	2.22 ± 0.08 ^a	34.4 ± 6.0 ^c
B Plants grown on 1/2 MS + 50 mM Suc
Col-0	0.78 ± 0.01	0.35 ± 0.02	1.64 ± 0.21	2.87 ± 0.06	49.8 ± 7.7
adg1-1/tpt-2	0.63 ± 0.06 ^c	0.21 ± 0.04 ^c,c	1.55 ± 0.21 ^c	2.66 ± 0.03 ^a	59.3 ± 9.0

Photosynthesis parameters were determined with the Imaging-PAM fluorometer using the integrated light source. F_v/F_m ratios were determined after the leaves were dark-adapted for at least 15 min. The OPSII values refer to steady state photosynthesis, which was attained 7-10 min after onset of illumination at a PFD of 300 μmol·m^-2·s^-1. For pigment and carbohydrate measurements leaves were harvested in the middle of the light period. The data represent the mean ± SE of n = 4 measurements. Significant differences between the data were analyzed according to the Welch test. The letters as superscripts denote ^a,aP < 0.01, ^b,bP < 0.02, ^c,cP < 0.05. Plain letters = comparison of adg1-1/tpt-2 with Col-0 at the respective growth conditions, italic letters = comparison of adg1-1/tpt-2 plants grown on 50 mM Suc with those grown on 1/2 MS as a control. There were no significant differences found between Col-0 grown either on 1/2 MS or 50 mM Suc.

ISSN: 1471-2229