Molecular mechanisms of gravity perception and signal transduction in plants

Abstract

Gravity is one of the environmental cues that direct plant growth and development. Recent investigations of different gravity signalling pathways have added complexity to how we think gravity is perceived. Particular cells within specific organs or tissues perceive gravity stimulus. Many downstream signalling events transmit the perceived information into subcellular, biochemical, and genomic responses. They are rapid, non-genomic, regulatory, and cell-specific. The chain of events may pass by signalling lipids, the cytoskeleton, intracellular calcium levels, protein phosphorylation-dependent pathways, proteome changes, membrane transport, vacuolar biogenesis mechanisms, or nuclear events. These events culminate in changes in gene expression and auxin lateral redistribution in gravity response sites. The possible integration of these signalling events with amyloplast movements or with other perception mechanisms is discussed. Further investigation is needed to understand how plants coordinate mechanisms and signals to sense this important physical factor.

A Core Regulatory Pathway Controlling Rice Tiller Angle Mediated by the LAZY1-Dependent Asymmetric Distribution of Auxin

“…In plants, gravitropism involves the perception of gravity and signal transduction cascades that lead to an asymmetric distribution of auxin and differential growth between the upper and lower sides of responding organs (Strohm et al, 2012). Genetic studies in Arabidopsis have identified several genes involved in shoot gravitropism such as SGR genes and PHOSPHOGLUCOMUTASE genes (Hashiguchi et al, 2013(Hashiguchi et al, , 2014Kim et al, 2016;Kolesnikov et al, 2016). Although other studies have used "omics" techniques and identified gravitropism-related genes or proteins in several species (Moseyko et al, 2002;Kimbrough et al, 2004;Hu et al, 2013Hu et al, , 2015Schenck et al, 2013;Taniguchi et al, 2014;Gerttula et al, 2015;Schüler et al, 2015), the direct link between tiller or branch angle and gravitropism has not yet been established.…”

On the growth and form of shoots

“…One of the most commonly observed of these movements is gravitropism, wherein plant shoots perceive the direction of gravity and regulate their growth to achieve a steady orientation with respect to gravity [2][3][4][5][6][7][8]. The perception of gravity occurs within specialized cells called statocytes through the sedimentation of intracellular statoliths [5,8,9] onto sensory structures. This mechanical signal leads to a differential growth across the cross section of a shoot and thence active (sentient) bending of the respective organ [5][6][7][8]10].…”

Simulated microgravity promotes the formation of tridimensional cultures and stimulates pluripotency and a glycolytic metabolism in human hepatic and biliary tree stem/progenitor cells

“…The transduction of the gravity signal on which its biologic effects rely on is currently under investigation 28,29 . Extracellular mechanic stimuli, capable to modulate cell metabolism and mitochondria, have been described primarily in plant cells 28,29 .…”

“…The transduction of the gravity signal on which its biologic effects rely on is currently under investigation 28,29 . Extracellular mechanic stimuli, capable to modulate cell metabolism and mitochondria, have been described primarily in plant cells 28,29 . In this contest the sensorial apparatus has been identified in membrane receptors, cytoskeletal, and intracellular messengers linked to the modulation of metabolic enzymes 28,29 .…”

“…Extracellular mechanic stimuli, capable to modulate cell metabolism and mitochondria, have been described primarily in plant cells 28,29 . In this contest the sensorial apparatus has been identified in membrane receptors, cytoskeletal, and intracellular messengers linked to the modulation of metabolic enzymes 28,29 . Aryl hydrocarbon receptor (AHR) a member of the basic-helix/loop/helix per-Arnt-sim (bHLH/PAS) family of “sensors” of foreign and endogenous signals, has been implicated in gravity sensation.…”