Regulation of Water Deficit-Induced Abscisic Acid Accumulation by Apoplastic Ascorbic Acid in Maize Seedlings

Abstract

Water deficit-induced abscisic acid (ABA) accumulation is one of the most important stress signaling pathways in plant cells. Redox regulation of cellular signaling has currently attracted particular attention, but much less is known about its roles and mechanisms in plant signaling. Herein, we report that water deficit-induced ABA accumulation could be regulated by ascorbic acid (AA)-controlled redox status in leave apoplast. The AA content in non-stressed leaves was approximately 3 µmol/g FW, corresponding to a mean concentration of 3 mmol/L in a whole cell. Because AA is mainly localized in the cytosol and chloroplasts, the volume of which is much smaller than that of the whole cell, AA content in cytosolic and chloroplast compartments should be much higher than 3 mmol/L. Water deficit-induced ABA accumulation in both leaf and root tissues of maize seedlings was significantly inhibited by AA and reduced glutathione (GSH) at concentrations of 500 µmol/L and was completely blocked by 50 mmol/L AA and GSH. These results suggest that the AA-induced inhibition of ABA accumulation should not occur at sites where AA exists in high concentrations. Although water deficit led to a small increase in the dehydroascorbic acid (DHA) content, no significant changes in AA content were observed in either leaf or root tissues. When compared with the whole leaf cell, the AA content in the apoplastic compartment was much lower (i.e. approximately 70 nmol/g FW, corresponding to 0.7 mmol/L). Water deficit induced a significant decrease (approximately 2.5-fold) in the AA content and an increase (approximately 3.4-fold) in the DHA content in the apoplastic compartment, thus leading to a considerably decreased redox status there, which may have contributed to the relief of AA-induced inhibition of ABA accumulation, alternatively, promoting water deficit-induced ABA accumulation. Reactive oxygen species (ROS) could not mimic water deficit in inducing ABA accumulation, suggesting that the inhibition of ABA accumulation by AA or GSH was not related to their ROS-scavenging ability. The results of the present study suggest that the redox status in the apoplastic compartment, as determined by AA and DHA, may play a vital role in the regulation of the signaling process for water deficit-induced ABA accumulation.

Deciphering Ascorbic Acid Regulatory Pathways in Ripening Tomato Fruit Using a Weighted Gene Correlation Network Analysis Approach

“…In this work, many hormone/signal‐related genes also were found in this positively related module including jasmonic acid regulatory protein gene, auxin response factor, ethylene response factor, gibberellin‐induced protein gene, calmodulin protein gene, and so on. These results show that AsA content is positively related to the hormones/signals such as jasmonic acid, auxin and ethylene, suggesting that AsA content in tomato fruit may be critically regulated by several hormones/signals synergistically, as previously suggested (Hu et al ; Lima‐Silva et al ). Nevertheless, it cannot be excluded that AsA may play significant roles in the regulatory pathways of those hormones/signals metabolism.…”

Variations in Growth, Photosynthesis and Defense System Among Four Weed Species Under Increased UV‐B Radiation

“…Activity of SOD, CAT and APX were measured according to Lei et al (2005). Ascorbic acid (ASA) contents were measured according to Hu et al (2005).…”

Proteome readjustments in the apoplastic space of Arabidopsis thaliana ggt1 mutant leaves exposed to UV-B radiation

“…The apoplast—i.e., the extraprotoplastic matrix of plant cells, including the cell wall—contains a number of enzymatic and non-enzymatic components involved in many physiological processes and is therefore important in the plant cell's response to both abiotic and biotic stress (Dietz, 1997 ; Agrawal et al, 2010 ). Being at the interface with the external environment, rapid fluctuations occur in this compartment as a consequence of unfavorable conditions, such as salinity (Hernandez et al, 2001 ), ozone (Jaspers et al, 2005 ) drought (Hu et al, 2005 ), and UV-B radiation (Pristov et al, 2013 ), with consequent changes in the concentrations and redox state of its components.…”