The locations and amounts of endogenous ions and elements in the cap and elongating zone of horizontally oriented roots of Zea mays L.: an electron-probe EDS study

摘要: We used quantitative electron-probe energy-dispersive x-ray microanalysis to localize endogenous Na, Cl, K, P, S, Mg and Ca in cryofixed freeze-dried cryosections of the cap (i.e. putative site graviperception) elongating zone gravicurvature) horizontally oriented roots Zea mays. Ca, K accumulate along lower side caps roots. The most dramatic asymmetries these ions occur apoplast, especially mucilage. could not detect any significant differences concentrations central cytoplasm columella cells upper sides horizontally-oriented However, increased amounts longitudinal walls suggest that may move down through tissue also accumulates (largely mucilage) roots, while Cl tend zone. Of ions, only increases concentration cortical vs These results indicate (1) gravity-induced differ significantly graviresponding (2) (3) growth correlates positively with cells, (4) apoplast (especially be an important component pathway via which rots are discussed relative mechanisms for graviperception gravicurvature