Role of Plant Hormones in Plant Response to Elevated CO2 Concentrations: Above- and Below-ground Interactions

Abstract

AbstractMany commercial greenhouses increase their atmospheric CO2 levels to enhance their productivity. However, this practice is energetically expensive, and frequently ventilating the greenhouse (to prevent plant diseases) releases CO2 into the atmosphere. While it is well known that elevated atmospheric CO2 (eCO2) can promote plant growth and development by affecting cell division, elongation, differentiation and stomatal regulation, our understanding of how phytohormones are involved in regulating plant growth under eCO2 is still limited. While eCO2 stimulates root growth and development, it is not clear whether the roots are responding to basipetal hormone transport and/or local changes in hormone homeostasis due to enhanced accumulation of sugars in the roots. Since enriching the root zone (RZ) with CO2 (RZ CO2) may be a cheaper and more sustainable alternative to aerial CO2 enrichment, we also review the effects of RZ CO2 enrichment on phytohormone concentrations. Much more work is needed to piece together our fragmentary understanding of how plants integrate long-distance hormone signalling pathways in response to eCO2.KeywordsElevated atmospheric CO2Root zone CO2 enrichmentRhizosphere CO2 movementRoot growthBasipetal hormone transportHormone homeostasis