Salt Stress Affects Cortical Microtubule Organization and Helical Growth in Arabidopsis

Abstract

Cortical microtubule arrays are critical in determining the growth axis of diffusely growing plant cells, and various environmental and physiological factors are known to affect the array organization. Microtubule organization is partly disrupted in the spiral1 mutant of Arabidopsis thaliana, which displays a right-handed helical growth phenotype in rapidly elongating epidermal cells. We show here that mutations in the plasma membrane Na(+)/H(+) antiporter SOS1 and its regulatory kinase SOS2 efficiently suppressed both microtubule disruption and helical growth phenotypes of spiral1, and that sos1 and sos2 roots in the absence of salt stress exhibited altered helical growth response to microtubule-interacting drugs at low doses. Salt stress also altered root growth response to the drugs in wild-type roots. Suppression of helical growth appeared to be specific to spiral1 since other helical growth mutants were not rescued. The effects of sos1 in suppressing spiral1 defects and in causing abnormal drug responses were nullified in the presence of the hkt1 Na(+) influx carrier mutation in roots but not in hypocotyls. These results suggest that cytoplasmic salt imbalance caused by insufficient SOS1 activity compromises cortical microtubule functions in which microtubule-localized SPIRAL1 is specifically involved.

The Microtubule Plus-End Tracking Proteins SPR1 and EB1b Interact to Maintain Polar Cell Elongation and Directional Organ Growth in Arabidopsis

“…The idea that +TIPs, and SPR1 in particular, may be targets of environmental signaling is supported further by studies of salt stress. Wang et al (2011) found that salt stress led to the 26S proteasome-based degradation of SPR1 protein, while Shoji et al (2006) found that salt stress affected cortical MT array organization and suppressed the right-handed helical growth phenotype of spr1 mutant roots.…”

Microtubules Are a Target for Self-Incompatibility Signaling in Papaver Pollen

“…Microtubule reorganization and/or apparent depolymerization occurs in response to specific abiotic stimuli (Bartolo and Carter, 1991;Himmelspach et al, 1999;Shoji et al, 2006). Several examples of the microtubule cytoskeleton alterations in response to biotic stimuli, such as infection by pathogenic fungi or symbiotic interactions with mycorrhiza or rhizobia, exist (for review, see Takemoto and Hardham, 2004).…”

“…Cortical microtubules are also involved in signal-response coupling. It has been shown that abiotic stimuli, such as gravity (Himmelspach et al, 1999), hormones (Shibaoka, 1994), freezing (Bartolo and Carter, 1991), and salt stress (Shoji et al, 2006), result in the reorientation or depolymerization of microtubules. Biotic interactions resulting in microtubule alterations also exist.…”

Phospholipids

“…[13][14][15] It has been well documented MTs and MFs take part in salt stress, heat shock, dehydration and drought. 10,12,13,[15][16][17][18] However, the exact mechanisms about how MTs and MFs sense cues and reorganize themselves in these processes remain to be elucidated.…”