Manipulation of arginase expression modulates abiotic stress tolerance in Arabidopsis: effect on arginine metabolism and ROS accumulation

Abstract

Arginine is an important medium for the transport and storage of nitrogen, and arginase (also known as arginine amidohydrolase, ARGAH) is responsible for catalyse of arginine into ornithine and urea in plants. In this study, the impact of AtARGAHs on abiotic stress response was investigated by manipulating AtARGAHs expression. In the knockout mutants of AtARGAHs, enhanced tolerances were observed to multiple abiotic stresses including water deficit, salt, and freezing stresses, while AtARGAH1- and AtARGAH2-overexpressing lines exhibited reduced abiotic stress tolerances compared to the wild type. Consistently, the enhanced tolerances were confirmed by the changes of physiological parameters including electrolyte leakage, water loss rate, stomatal aperture, and survival rate. Interestingly, the direct downstream products of arginine catabolism including polyamines and nitric oxide (NO) concentrations significantly increased in the AtARGAHs-knockout lines, but decreased in overexpressing lines under control conditions. Additionally, the AtARGAHs-overexpressing and -knockout lines displayed significantly reduced relative arginine (% of total free amino acids) relative to the wild type. Similarly, reactive oxygen species accumulation was remarkably regulated by AtARGAHs under abiotic stress conditions, as shown from hydrogen peroxide (H2O2), superoxide radical () concentrations, and antioxidant enzyme activities. Taken together, this is the first report, as far as is known, to provide evidence that AtARGAHs negatively regulate many abiotic stress tolerances, at least partially, attribute to their roles in modulating arginine metabolism and reactive oxygen species accumulation. Biotechnological strategy based on manipulation of AtARGAHs expression will be valuable for future crop breeding.

In vivo role ofArabidopsisarginase in arginine metabolism and abiotic stress response

“…[16][17][18][19][20][21][22][23] Consistently, we found that the knockout mutants and overexpression transgenic plants showed opposite abiotic stress responses and manipulation of arginase expression modulate both ADC and NOS pathway. 5 Interestingly, AtARGAHs could modulate ROS accumulation and antioxidant enzyme activities under abiotic stress conditions, which is consistent with the results that both polyamines and NO play complex roles to deal with ROS derived from environmental stresses. 4,5,16,21 All these results may give new insights and evidences about crosstalk of NO and polyamines under abiotic stress conditions, and functional link between NO and polyamines metabolisms and ROS accumulation in vivo.…”

“…5 Interestingly, AtARGAHs could modulate ROS accumulation and antioxidant enzyme activities under abiotic stress conditions, which is consistent with the results that both polyamines and NO play complex roles to deal with ROS derived from environmental stresses. 4,5,16,21 All these results may give new insights and evidences about crosstalk of NO and polyamines under abiotic stress conditions, and functional link between NO and polyamines metabolisms and ROS accumulation in vivo. 4,5,16,21 We hypothesized that NO and polyamines might share the same pathways to activate rapid stress responses in the plant.…”

“…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. [2][3][4][5] Our previous research together with other published data confirmed that proper levels of NO might be necessary and beneficial for plants in response to both abiotic stress and disease resistance. [6][7][8][9][10][11]13,14 As to polyamines, overexpression of several polyamine metabolism genes including ADC and SPMS resulted in increased polyamines and enhanced abiotic stress tolerance, while knockdown of these genes had the opposite results.…”

“…[2][3][4][5] If arginase expression was modulated, the direct insight was to examine the arginine accumulation. Although changes of AtARGAHs expression had no significant effect on upstream ArticLe AddenduM the production of nitrogen species and reactive oxygen species (ROS).…”

“…[1][2][3][4][5] As shown in Figure 1, arginase (also known as ARGAH in Arabidopsis) is responsible for catalyze of arginine to ornithine and urea, and arginine decarboxylase (ADC) can metabolize arginine to agmatine and further to polyamines including putrescine, spermidine, spermine, etc. 2,3,5 Additionally, although nitric oxide synthase (NOS) has not been cloned in higher plants, similar NOS activity of animals has been detected in many plant species by many research groups. [6][7][8][9][10][11] And it has been confirmed that NO might be generated primarily during the conversion of arginine to citrulline by the NOS, especially in responses to several biotic and abiotic stresses.…”