Molecular and physiological responses of Iranian Perennial ryegrass as affected by Trinexapac ethyl, Paclobutrazol and Abscisic acid under drought stress.

Drought stress is the major limiting factor which affects turfgrass management in area with restricted rainfall or irrigation water supply. Trinexapac ethyl (TE), Paclobutrazol (PAC) and Abscisic acid (ABA) are three plant growth regulators (PGRs) that are commonly used on turf species for increasing their tolerance to different environmental stresses such as drought. However, little is known about the impact of PGRs on stress tolerance of Iranian Perennial ryegrass (Lolium perenne). The present study was conducted to examine the visual and physiological changes of Iranian Perennial ryegrass in response to foliar application of TE, PAC, and ABA under drought stress conditions. According to the obtained results, application of all three PGRs considerably restored visual quality of drought exposed plants. TE treatment increased chlorophyll content, proline content and resulted in less malondialdehyde (MDA) in drought stressed Perennial ryegrass. Application of all PGRs enhanced the relative water content (RWC) and decreased the electrolyte leakage (EL) and Hydrogen peroxide contents (H2O2 content) of plants under drought stress, though the impact of TE was more pronounced. Throughout the experiment, TE- and ABA-treated plant showed greater soluble sugar (SSC) content as compared to the control. Antioxidant enzymes activities of drought exposed plants were considerably increased by PGRs application. Catalase (CAT) and Superoxide dismutase (SOD) activities were greater in TE-treated grasses followed by PAC-treated plants. Ascorbate peroxidase (APX) and peroxidase (POD) activities were significantly enhanced by TE and ABA application. The results of the present investigation suggest that application of TE, ABA and PAC enhances drought tolerance in Perennial ryegrass. TE, PAC and ABA were all effective in mitigating physiological damages resulting from drought stress, however the beneficial effects of TE were more pronounced. The result obtained of real time-PCR suggested that regulation of CAT, APX, POD and SOD genes expression at translational levels highly depended on the application of TE, PAC and ABA. Also, the results showed that deletion mutation in SOD and POD genes were not leading to enzyme inactivation.

Sheikh Mohammadi MH ，Etemadi N ，Arab MM ，Aalifar M ，Arab M ，Pessarakli M ... -  《-》

Responses of antioxidant gene, protein and enzymes to salinity stress in two genotypes of perennial ryegrass (Lolium perenne) differing in salt tolerance.

Salinity could damage cellular membranes through overproduction of reactive oxygen species (ROS), while antioxidant capacities play a vital role in protecting plants from salinity caused oxidative damages. The objective of this study was to investigate the toxic effect of salt on the antioxidant enzyme activities, isoforms and gene expressions in perennial ryegrass (Lolium perenne L.). Salt-tolerant 'Quickstart II' and salt-sensitive 'DP1' were subjected to 0 and 250 mM NaCl for 12 d. Salt stress increased the content of lipid peroxidation (MDA), electrolyte leakage (EL) and hydrogen peroxide (H₂O₂), to a greater extent in salt-sensitive genotype. Salt-stressed plant leaves exhibited a greater activity of superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11) at 4d after treatment (DAT), but a lower level of enzyme activity at 8 and 12d, when compared to the control. Catalase (CAT, EC 1.11.1.6) activity was greater at 4 DAT and thereafter decreased in salt tolerant genotype relative to the control, whereas lower than the control during whole experiment period for salt-sensitive genotype. There were different patterns of five isoforms of SOD, POD and two isoforms of APX between two genotypes. Antioxidant gene expression was positively related to isoenzymatic and total enzymatic activities during 12-d salt-treated leaves of two genotypes, with a relatively higher level in salt-tolerant genotype. Thus, salt tolerance could be related to the constitutive/induced antioxidant gene, leading to more efficient enzyme stimulation and protection in perennial ryegrass.

Hu L ，Li H ，Pang H ，Fu J ... -  《-》

Exogenous abscisic acid increases antioxidant enzymes and related gene expression in pepper (Capsicum annuum) leaves subjected to chilling stress.

Guo WL ，Chen RG ，Gong ZH ，Yin YX ，Ahmed SS ，He YM ... -  《Genetics and Molecular Research》

Alleviation of Drought Stress by Hydrogen Sulfide Is Partially Related to the Abscisic Acid Signaling Pathway in Wheat.

Ma D ，Ding H ，Wang C ，Qin H ，Han Q ，Hou J ，Lu H ，Xie Y ，Guo T ... -  《PLoS One》

Coronatine enhances drought tolerance via improving antioxidative capacity to maintaining higher photosynthetic performance in soybean.

Coronatine (COR), a structural and functional mimic of jasmonates, is involved in a wide array of effects on plant development and defence responses. This study was conducted to explore the role of exogenously applied COR in alleviating the adversities of drought stress in soybean. COR treatment markedly increased the activities of antioxidant enzymes and proline content, and reduced the accumulation of malondialdehyde and hydrogen peroxide under drought stress. Thus, COR-treated plants had higher leaf relative water content and lower electrolye leakage, which led to higher chlorophyll content, activities of RuBPCase and PEPCase, and net photosynthetic rate compared to control plants exposed to drought. COR also increased maximal efficiency of PS II photochemical reaction and photochemical quenching coefficient, but decreased non-photochemical quenching coefficient. These beneficial effects led to enhanced photosynthetic performance and the translocation of assimilated (14)C which promoted growth and accumulation of dry biomass in COR-treated soybean plants subjected to drought. Interestingly, COR application did not affect the growth and biomass accumulation under well-watered condition. These results suggested the involvement of COR on improving drought tolerance in soybean by modulating antioxidant systems and membrane stability to maintain higher photosynthetic performance.

Hao L ，Wang Y ，Zhang J ，Xie Y ，Zhang M ，Duan L ，Li Z ... -  《-》