Abscisic Acid Translocation and Influence of Water Stress on Grain Abscisic Acid Content

Abstract

The movement of foliar applied [1-¹⁴C]abscisic acid (ABA) in wheat plants (Triticum aestivum L., cv. Kolibri) was investigated at two stages of grain development (1000 grains, weight 19 and 24 g dry matter). [1−¹⁴C]ABA seemed to be readily translocated within 12 h into the developing grains as well as in other plant parts. A subsequent rapid metabolism took place leading to a decreased activity of the ABA-containing chromatogram fraction in the younger plants 48 h after application. The metabolism seemod to be less intensive in the older grains, where the activity running with the ABA increased over 64 h. Treating the leaves of barley plants (Hordeum vulgare, L., cv. Union) 2 weeks after anthesis with a gentle stream of warm air (36° C) resulted in a significant increase in the ABA content of all parts of the ear. The results mentioned above indicate that this may be partially due to translocation from other parts of the plant such as the leaves.