XVI International Botanical Congess

Previous work established that ABA accumulation is required for root growth maintenance in water-stressed maize seedlings, and acts by preventing ethylene-induced growth inhibition. We are exploring this interaction in detail using two novel systems. First, gas analysis shows that in roots of intact, water-stressed maize seedlings ethylene production increases several-fold in ABA-deficient roots and that ethylene sensitivity is likely altered. Second, Arabidopsis seedlings have been grown at constant and reproducible low water potentials on agar plates. Root elongation continues at low water potentials that inhibit shoot growth, and under mild stress an increase in root elongation occurs. The roles of ABA and its interaction with ethylene are being studied using mutants defective in ABA synthesis and/or ethylene sensitivity.