Stomatal Conductance Depends on Abscisic Acid Production in Both Guard Cells and in Phloem Companion Cells

Abstract

The question how plants use water is important as water availability is often a limiting factor for plant growth. Stomata are mainly responsible for water loss from plant tissues and, therefore, regulatory mechanisms controlling stomatal apertures are in the research focus of plant water management. Abscisic acid (ABA) has an important role in reducing stomatal conductance, however, importance of ABA biosynthesis in guard cells and in phloem is not fully studied. To address this question, we generated transgenic plants with restored ABA biosynthesis either in guard cells or in phloem by using tissue-specific promoters. Our study shows that both guard cells and phloem companion cells can produce ABA in quantities which are enough to regulate plant development and stomatal conductance on the level of wildtype plants.