Abscisic acid regulates root growth under osmotic stress conditions via an interacting hormonal network with cytokinin, ethylene and auxin

Abstract

Summary Understanding the mechanisms regulating root development under drought conditions is an important question for plant biology and world agriculture.We examine the effect of osmotic stress on abscisic acid (ABA), cytokinin and ethylene responses and how they mediate auxin transport, distribution and root growth through effects on PIN proteins. We integrate experimental data to construct hormonal crosstalk networks to formulate a systems view of root growth regulation by multiple hormones.Experimental analysis shows: that ABA‐dependent and ABA‐independent stress responses increase under osmotic stress, but cytokinin responses are only slightly reduced; inhibition of root growth under osmotic stress does not require ethylene signalling, but auxin can rescue root growth and meristem size; osmotic stress modulates auxin transporter levels and localization, reducing root auxin concentrations; PIN1 levels are reduced under stress in an ABA‐dependent manner, overriding ethylene effects; and the interplay among ABA, ethylene, cytokinin and auxin is tissue‐specific, as evidenced by differential responses of PIN1 and PIN2 to osmotic stress.Combining experimental analysis with network construction reveals that ABA regulates root growth under osmotic stress conditions via an interacting hormonal network with cytokinin, ethylene and auxin.

Proline Accumulation Is Regulated by Transcription Factors Associated with Phosphate Starvation

“…S8). Blocking of ABA biosynthesis was reported to release inhibition of root growth under moderate osmotic stress (Rowe et al, 2016), supporting our finding that ABA is implicated in growth control during stress. Growth restriction during osmotic stress can be mediated by growth-repressing DELLA proteins, which are stabilized by ABA, but are promoted to degradation by gibberellins (Achard et al, 2006;Golldack et al, 2013).…”

“…These results suggest that there is an intimate relationship among starvation, senescence-related pathways, and ABA signaling, which regulates responses to phosphate deficiency. ABA triggers defenses during drought or high-soil salinity and mediates growth inhibition (Finkelstein, 2013;Rowe et al, 2016). We found that on phosphate-deficient medium, rosette growth of the ABA deficient aba2-3 mutant was less reduced than wild type, suggesting that ABA is implicated in growth inhibition in such nutritional stress.…”

The Role and Regulation of ABI5 (ABA-Insensitive 5) in Plant Development, Abiotic Stress Responses and Phytohormone Crosstalk

“…PIN1 , a gene encoding the auxin transporter, showed a decreased expression when osmotic stress was applied (Rowe et al, 2016). Salt stress disturbed the expression of the PIN genes and stabilized AXR3/IAA17, which in turn reduced the size of the root meristem because of the lower auxin level (Liu et al, 2015).…”

A Genome-Scale Analysis of the PIN Gene Family Reveals Its Functions in Cotton Fiber Development

“…The influx and efflux carriers of the auxin transporter that are distributed in the plasma membrane are grouped into three major categories: auxin resistant 1/like aux1 (AUX1/LAX) influx carriers, P-glycoprotein (MDR/PGP/ABCB) efflux/conditional transporters, and plant specific PIN-FORMED (PIN) efflux carriers. The PINs are known as the most important auxin carriers that control the auxin PAT process (Péret et al, 2012; Adamowski and Friml, 2015; Yue et al, 2015; Row et al, 2016). Recently, PIN-LIKES (PILS) family, which are localized to the endoplasmic reticulum and involved in the regulation of intracellular auxin homeostasis, was characterized as a novel putative auxin carriers (Barbez et al, 2012; Feraru et al, 2012).…”