Trehalose Protects Maize Plants from Salt Stress and Phosphorus Deficiency

Abstract

This study was undertaken to elucidate the role of trehalose (Tre) in mitigating oxidative stress under salinity and low P in maize. Eight-day-old maize seedlings of two maize varieties, BARI Hybrid Maize-7 and BARI Hybrid Maize-9 were subjected to salinity (150 mM NaCl), low P (5 µM KH2PO4) and their combined stress with or without 10 mM Tre for 15-d.Salinity and combined stress significantly inhibited the shoot length, root length, and root volume, whereas, low P increased the root length and volume in both genotypes. Exogenous Tre in the stress treatments increased all of the growth parameters as well as decreased the salinity, low P and combined stress-mediated Na+/K+, ROS, MDA, LOX activity and MG in both genotypes. Under salinity and low P stress, the SOD activity increased in both genotypes, but the activity decreased in combined stress. POD activity increased in all stress treatments. Interestingly, Tre application enhanced the SOD activity in all the stress treatments but inhibited the POD activity. Both CAT and GPX activity were increased by saline and low P stress while the activities inhibited in combined stress. Similar results were found for APX, GR, and DHAR activities in both genotypes. However, MDHAR activity was inhibited in all the stresses. Interestingly, Tre enhanced CAT APX, GPX, GR, MDHAR and DHAR activities suggesting the amelioration of ROS scavenging in maize under all the stresses. Increased GST activity in presence or absence of Tre might involve in detoxification of hydroperoxides as well as leaf senescence. On the other hand, increased glyoxalase activities in saline and low P stress in BHM-9 suggested better MG detoxification system because of down-regulation of Gly-I activity in BHM-7 in those stresses. Tre also increased the glyoxalase activities in both genotypes under all the stresses. Tre improved the growth in maize seedlings by decreasing Na+/K+, ROS, MDA, and MG through regulating antioxidant and glyoxalase systems.

The genome of stress tolerant crop wild relativePaspalum vaginatumleads to increased biomass productivity in the cropZea mays

“…A non-targeted metabolic profiling of six legume plants in the Lotus genus under drought conditions revealed a significant increase in trehalose abundance across all species tested 89 . In maize, external trehalose treatment enhanced antioxidant activities under high salinity and P-deficient conditions, thus achieving better seedling growth 90 . Genetically modified rice plants that over-expressed a fusion gene encoding both Escherichia coli Trehalose-6-phosphate synthase and Trehalose-6-phosphate phosphatase, which are responsible for trehalose biosynthesis, exhibited 200-fold greater accumulation of trehalose and significantly higher tolerance to drought, salinity, and cold stress 91 .…”

The Stay-green Mutation Contributes to Enhanced Antioxidative Competence and Delays Leaf Senescence in Soybean Hybrid Z1

“…The ASA-GSH pathway comprises four enzymes, namely, APX, MDHAR, DHAR and GR (Raja et al 2017) and plays a key role in ROS detoxification by regulating intracellular levels of H 2 O 2 (Hasanuzzaman et al 2019;Raja et al 2020). In higher plants, H 2 O 2 is produced predominantly in the chloroplasts and peroxisomes, in which APX is widely distributed and reduces H 2 O 2 to H 2 O via the oxidation of ASA, thereby protecting these structures from oxidative damage (Rohman et al 2019).…”

“…The ASA-GSH pathway comprises four enzymes, namely, APX, MDHAR, DHAR and GR (Raja et al 2017) and plays a key role in ROS detoxification by regulating intracellular levels of H 2 O 2 (Hasanuzzaman et al 2019;Raja et al 2020). In higher plants, H 2 O 2 is produced predominantly in the chloroplasts and peroxisomes, in which APX is widely distributed and reduces H 2 O 2 to H 2 O via the oxidation of ASA, thereby protecting these structures from oxidative damage (Rohman et al 2019). The two Chl APX isogenes tAPX and sAPX are located in the thylakoid membrane and chloroplast stroma, respectively (Qiu et al 2020), the former of which is highly sensitive to exogenous H 2 O 2 (in contrast to sAPX) (Li 2014), and its expression is rapidly suppressed during senescence (Panchuk et al 2005 (Li 2014), and in the present study, we found that the expression of APX6 and APX3 (peroxisome APX) was significantly repressed during leaf senescence, whereas that of APX7 and APX2 (cytoplasmic APXs) was gradually up-regulated concomitant with H 2 O 2 accumulation during late senescence.…”

“…The three remaining key enzymes of the ASA-GSH cycle, MDHAR, DHAR, and GR, are responsible for the reduction of MDHA and DHA and play roles in maintaining the regeneration of ASA and GSH (Rohman et al 2019). A marked increase in APX activity is concomitant with an increase in ASA levels in maize leaves (Zhang et al 2014;Rohman et al 2019), whereas a deficiency in ASA can lead to the passivation or instability of APX enzyme activity (Ishikawa and Shigeoka 2008). In the present study, we detected higher levels of MDHAR, DHAR, and GR expression in Z1 during the filling stages, thereby indicating the enhanced regeneration of ASA and GSH in this variety, which promotes the effective removal of H 2 O 2 and, consequently, delays leaf senescence.…”