Isolated root tips of pea (Pisum sativum L. cv. Feltham First) and Commelina communis L. were air-dried until they lost between 10% and 40% of their fresh weight, followed by a period of incubation at these reduced water contents. These treatments resulted in increased ABA production, suggesting that root tips of both species have the capacity to synthesize ABA in increased amounts when water deficits develop in the root. The ABA concentration in pea roots increased linearly as turgors fell below about 0-15 M Pa and relative water contents (R WC) fell below 90%. Commelina roots produced more ABA when RWC fell below a similar value but the threshold turgor for increased ABA production in Commelina roots was around 0-30 MPa. Roots of intact plants loaded with ABA as a result of incubation in solutions of varying concentrations provided ABA to leaves which resulted in increased ABA concentrations in the leaves when these were assayed several hours later. This occurred when these roots were not contributing substantially to transpirational flux. Leaves on shoots that were enclosed and darkened and therefore not transpiring, did not accumulate ABA from 'loaded* roots. A role for root-sourced ABA in root-to-shoot communication of the effects of soil drying is discussed.
|Number of pages||9|
|Journal||Journal of Experimental Botany|
|Publication status||Published - 1 Dec 1987|
Scopus Subject Areas
- Plant Science
- Water relations