PLANT PHYSIOLOGY , Vol 109, Issue 2 593-601, Copyright © 1995 by American Society of Plant Biologists
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WHOLE PLANT, ENVIRONMENTAL, AND STRESS PHYSIOLOGY |
Translatable RNA Populations Associated with Maintenance of Primary Root Elongation and Inhibition of Mesocotyl Elongation by Abscisic Acid in Maize Seedlings at Low Water Potentials
I. N. Saab, THD. Ho and R. E. Sharp
Plant Science Unit, University of Missouri, Columbia, Missouri 65211 (I.N.S., R.E.S)
Previous work indicated that accumulation of abscisic acid (ABA) acts
differentially to maintain elongation of the primary root and inhibit
elongation of the mesocotyl of maize (Zea mays L.) seedlings at low water
potentials ([psi]w). Subsequent results indicated specific locations in the
elongation zones where elongation is maintained, inhibited, or unaffected
by endogenous ABA at low [psi]w. This information was utilized in this
study to identify in vitro translation products of RNA associated with the
maintenance or inhibition of elongation in the primary root and mesocotyl,
respectively, by endogenous ABA at low [psi]w. The results distinguished
products associated specifically with the elongation responses from those
nonspecifically associated with ABA accumulation or low [psi]w, as well as
normal cell development and maturation. In the primary root, the
maintenance of elongation at low [psi]w by ABA was associated with the
maintenance of expression of three products that were also expressed during
elongation at high [psi]w, the expression of a novel product, and the
suppression of two products. In the mesocotyl, the inhibition of elongation
by ABA after transplanting to low [psi]w was associated with the induction
of a novel translation product. However, the induction of this product, as
well as accumulation of ABA and inhibition of elongation, occurred without
a decline in tissue water content. The results demonstrate the necessity of
examining the association of gene expression with elongation responses to
low [psi]w with a high degree of spatial resolution.
