Table 1.

Chlorophyll Content and Chloroplast Number in Differently Aged Leaves of mex1 and Wild-Type.

		Mean chlorophyll content (SPAD units)		Mean chloroplast number per mesophyll cell
	Leaf age	16-h photoperiod	12-h photoperiod	12-h photoperiod
Wild-type	Young	33.1 ± 0.3	35.1 ± 0.4	11.1 ± 0.4
	Mature	30.6 ± 0.5	33.1 ± 0.6	73.1 ± 2.0
	Old	23.7 ± 0.4	29.4 ± 0.6	n.d.
mex1	Young	26.7 ± 1.7	29.9 ± 1.6*	9.4 ± 0.3*
	Mature	20.1 ± 0.6*	25.8 ± 0.2*	35.0 ± 1.6*
	Old	12.3 ± 0.7*	21.7 ± 0.5*	n.d.

Plants were grown and analyzed in independent experiments. For chlorophyll contents, the values are the means ± SE of three to six measurements on different plants. Measurements were made using a SPAD chlorophyll meter and expressed on a leaf area basis. For the 16-h photoperiod, old, mature, and young leaves (leaf numbers 1, 3–4, 7–8, respectively) of 3-week-old plants were analyzed. For the 12-h photoperiod, 4-week-old plants were analyzed (leaf numbers 1, 6–7, 10–11). For chloroplast numbers, values are the mean chloroplast count ± SE of 50 mesophyll cells prepared from three leaves (mature leaf, 7–8; young leaf, 14) from wild-type and mex1 plants (4 and 5 weeks old, respectively). Values for mex1 marked with an asterisk are significantly different from the corresponding wild-type values (student's t-test, p ≤ 0.05). n.d., not determined.