01117naa a2200133 a 450000100080000000500110000800800410001910000180006024500980007826000090017652007290018570000180091477300510093216480361998-05-21       1980    bl ---       0--  u    #d1 aHIRSCH, A. M.  aUltrastructural changes in sunflower root cells relation to boron deficiency and added auxin.  c1980  aThe responses of sunflower root cells to conditions of boron deficiency and to the addition of exogenous auxin were studied on the utrastructural level. Although gross morphological effects such as inhibition of root elongation and a change in the direction of cell expansion from longitudinal to radial are similar in both auzin-treated and boron-deficient seedling roots. ultrastructural changes are different in the two treatments. An increase in cell wall thickness and a loss of membrane integrity are seen as early as 6h in seedlings grown without boron. Auxin-treated root cells do not show this response. A role for boron may involve maintenance of membrane integrity rather than determining endogenous auxin levels.1 aTORREY, J. G.  tCandian Journal Botanygv.58, p.856-866, 1980.