Table 1.

Glucan-Bound Phosphate Content Is Higher in the sex4 Mutant Than in Wild-Type Plants

	Glucan-Bound Phosphate
	(nmol P μmol−1 Glc Equivalents)		(nmol P g−1 FW)
	Starch	Amylopectin	Starch	Phospho-Oligosaccharides	Total
Wild type	1.3 ± 0.1	1.5 ± 0.1	89.4 ± 8.3	ND	89.4 ± 8.3
sex4	0.9 ± 0.0	1.4 ± 0.1	134.7 ± 5.6	452.2 ± 82.5	586.9 ± 109.8

Arabidopsis wild-type and sex4 mutant plants were harvested at the end of the light period. Leaf starch was purified, and the amylopectin content was determined to be 91.8% ± 0.1% and 65.2% ± 1.1% for wild-type and sex4 starch, respectively (mean ± se; n = 3). Starch-bound phosphate from the same starch preparation was determined. Quantification of starch and phospho-oligosaccharides on a fresh weight (FW) basis was done with a different batch of plants as described (see Methods; plants harvested at the end of the light period). Values represent the mean ± se (n = 5 individual plants). Note that the phosphate content of phospho-oligosaccharides is slightly underestimated because it was assumed that each phospho-oligosaccharide is only singly phosphorylated. ND, not detectable.