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Cellular differentiation and tissue partitioning in caps of primary and lateral roots of Helianthus annuus
- Moore, R.
- Annals of botany 1985 v.55 no.3 pp. 367-373
- Helianthus annuus, roots, cell growth, cells, mucilages
- Cellular and tissue volumes in caps of primary and lateral roots of Helianthus annuus have been measured in order to determine quantitatively how tissues and their functions are partitioned in root caps. Patterns of change in cellular dimensions and volumes are similar in caps of primary and lateral roots. Significant increases in cellular dimensions and volume occur during the differentiation of columella cells and the innermost peripheral cells. There are no significant changes in cellular dimensions as either (i) the production and secretion of mucilage begins, or (ii) cells are sloughed from the cap. Tissues are partitioned similarly in caps of primary and lateral roots. indeed, root caps allocate 7–8 per cent of their volume for regeneration (i.e. calyptrogen tissue), 16–19 per cent of their volume for graviperception (i.e. columella tissue), and approx. 38 per cent of their volume for the production and secretion of mucilage. These results are discussed relative to patterns of cellular differentiation and tissue function in root caps.