The polyamine spermine protects against high salt stress in Arabidopsis thaliana

Abstract

It is well known that changes in abiotic conditions such as the concentration of ions, temperature and humidity lead to modulation of polyamine contents in plants. However, little is known about the relevant parts these polyamines play in abiotic stress responses. Here we addressed a specific role of spermine during high salt stress using an Arabidopsis double knockoutmutant plant (acl5/spms) which cannot produce spermine. The mutant showed higher sensitivity to high salt than wild type plants. This phenotype was cured by exogenous spermine but not by the other polyamines putrescine and spermidine, suggesting a strong link between spermine-deficiency and NaCl-hypersensitivity. The mutant was also hypersensitive to high levels of KCl but not to MgCl 2 or to high osmoticum. NaCl-hypersensitivity of the mutant was compromised by treatment with Ca 2+ channel blockers. Moreover, the mutant showed poor growth on Ca 2+ -depleted Murashige-Skoog agar media. The data suggest that the absence of spermine causes an imbalance in Ca 2+ homeostasis in the mutant plant. Based on the data obtained, we propose a model for a role of spermine in high salt stress responses.

Polyamines: potent modulators of plant responses to stress

“…These findings were further strengthened from molecular studies that double knockout mutants of A. thaliana (acl5/spms) incapable of producing Spm, showed higher sensitivity to salt stress than wild type plants. This phenotype was rescued by exogenous application of Spm but not by Put and Spd indicating a strong link between Spm deficiency and hypersensitivity to NaCl (Yamaguchi et al 2006).…”

“…For example, expression of ADC2 and SPMS involved in Spm-biosynthesis are regulated by ABA, described in A. thaliana in response to salt stress (Yamaguchi et al 2006).…”

Speculation: Polyamines are important in abiotic stress signaling

“…The overexpression of vacuolar cation/H + exchangers was observed in spermine synthesis deficient plants, suggesting that polyamines have a role in the regulation of the vacuolar Ca 2+ level [57]. They are also able to block vacuolar cation channels in the sequence Page 14 of 33 A c c e p t e d M a n u s c r i p t 14 spermine 4 + > spermidine 3 + > putrescine 2 + .…”

In vivo role ofArabidopsisarginase in arginine metabolism and abiotic stress response

“…Although changes of AtARGAHs expression had no significant effect on upstream ArticLe AddenduM the production of nitrogen species and reactive oxygen species (ROS). [6][7][8][9][10][11][13][14][15][16][17][18][19][20][21][22][23][24] Among multiple signaling molecules, NO and polyamines might be ideal candidates to integrate several environment stress responses, but the crosstalk of NO and polyamines is complex and needs to be further dissected. 1,4,17 As shown in Figure 1, manipulating the expression of AtARGAHs supplied a good version to investigate the link between NO and polyamines, especially in plant responses to abiotic stress.…”