Co-regulation of water and K+ transport in sunflower plants during water stress recovery

16-day-old sunflower (Helianthus annuus L.) plants were subjected to deficit irrigation for 12 days. Following this period, plants were rehydrated for 2 days to study plant responses to post-stress recovery. The moderate water stress treatment applied reduced growth in all plant organs and the accumulation of K+ in the shoot. After the rehydration period, the stem recovered its growth and reached a similar length to the control, an effect which was not observed in either root or leaves. Moreover, plant rehydration after water stress favored the accumulation of K+ in the apical zone of the stem and expanding leaves. In the roots of plants under water stress, watering to field capacity, once the plants were de-topped, rapidly favored K+ and water transport in the excised roots. This quick and short-lived response was not observed in roots of plants recovered from water stress for 2 days. These results suggest that the recovery of plant growth after water stress is related to coordinated water and K+ transport from the root to the apical zone of the stem and expanding leaves. This stimulation of K+ transport in the root and its accumulation in the cells of the growing zones of the stem must be one of the first responses induced in the plant during water stress recovery. (C) 2016 Elsevier GmbH. All rights reserved.