FIGURE 4.

The small branched glucans in the isa3lda double mutant are liberated by AMY3. Plants harvested at the end of the night were immediately frozen in liquid N₂. Samples were extracted using perchloric acid. Note the difference in the x axes. A, soluble malto-oligosaccharides in isa3, isa3lda, amy3isa3, and amy3isa3lda mutants, analyzed by HPAEC-PAD. Representative chromatograms are shown. Only isa3lda contains small branched glucans. Elution times of glucans with d.p. 6–8 are indicated by dashed lines. Bars illustrate the bimodal distribution of glucans with one branch point (black bar) and two or more branch points (gray bar; see “Results”). B, soluble malto-oligosaccharides of isa3lda mutants were fractionated by HPAEC. Those eluting between the retention times corresponding to linear chains of d.p. 8 and 9 were collected and debranched enzymatically, yielding linear chains of d.p. 3 and 6. C, chains eluting between the retention times corresponding to linear chains of d.p. 14 and 15 were collected and debranched enzymatically, yielding linear chains of d.p. 3, 6, and 9.