Calcium: The Missing Link in Auxin Action

Abstract

Due to their sessile lifestyles, plants need to deal with the limitations and stresses imposed by the changing environment. Plants cope with these by a remarkable developmental flexibility, which is embedded in their strategy to survive. Plants can adjust their size, shape and number of organs, bend according to gravity and light, and regenerate tissues that were damaged, utilizing a coordinating, intercellular signal, the plant hormone, auxin. Another versatile signal is the cation, Ca2+, which is a crucial second messenger for many rapid cellular processes during responses to a wide range of endogenous and environmental signals, such as hormones, light, drought stress and others. Auxin is a good candidate for one of these Ca2+-activating signals. However, the role of auxin-induced Ca2+ signaling is poorly understood. Here, we will provide an overview of possible developmental and physiological roles, as well as mechanisms underlying the interconnection of Ca2+ and auxin signaling.

The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis

“…Stimulation of cytosolic Ca 2+ transients by auxin has been reported recently (Monshausen et al, 2011), and critical roles in mediating auxin responses have been suggested for intracellular Ca 2+ (Vanneste and Friml, 2013). Therefore, it is interesting to note that the mitochondrial matrix response to NAA was far more pronounced than that of the cytosol when measured in the root tip, a hot spot of auxin regulation (Figures 6 and 7).…”

SAUR Proteins as Effectors of Hormonal and Environmental Signals in Plant Growth

“…Numerous studies have suggested that Ca 2+ is involved in auxin signaling or responses (reviewed in Vanneste and Friml, 2013). Auxin induces a rapid and transient increase of cytosolic Ca 2+ concentration in various plant species.…”

Calcium mobilizations in response to changes in the gravity vector inArabidopsisseedlings

“…The processes from the [Ca 2+ ] c -increase to the gravitropic response, which are highly likely auxin dependent, 54 are also not identified yet, and left for future studies.…”