title: Molecular and physiological responses of Iranian Perennial ryegrass as affected by Trinexapac ethyl, Paclobutrazol and Abscisic acid under drought stress.
abstract: 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 (H2O2content) 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.
authors.affiliation: Department of Horticulture, College of Agriculture, Isfahan University of Technology, 8415683111 Isfahan, Iran.
authors.forename: Mohammad Hossein
authors.initials: MH
authors.lastname: Sheikh Mohammadi
authors.affiliation: Department of Horticulture, College of Agriculture, Isfahan University of Technology, 8415683111 Isfahan, Iran.
authors.forename: Nematollah
authors.initials: N
authors.lastname: Etemadi
authors.affiliation: Department of Horticultural Sciences, College of Abooraihan, University of Tehran (UT), Tehran, Iran.
authors.forename: Mohammad Mehdi
authors.initials: MM
authors.lastname: Arab
authors.affiliation: Young Researchers and Elite Club, Hamedan Branch, Islamic Azad University, Hamedan, Iran. Electronic address: m_alifar@ut.ac.ir.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Aalifar
authors.affiliation: Department of Horticultural Sciences, College of Abooraihan, University of Tehran (UT), Tehran, Iran.
authors.forename: Mostafa
authors.initials: M
authors.lastname: Arab
authors.affiliation: School of Plant Sciences, The University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Pessarakli
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism; D002241:Carbohydrates / Q000032:analysis; D002734:Chlorophyll / Q000378:metabolism; D003521:Cyclopropanes / Q000494:pharmacology*; D004573:Electrolytes / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D008129:Lolium / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000502:physiology*; D008315:Malondialdehyde / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D011392:Proline / Q000378:metabolism; D011809:Quinones / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D012995:Solubility; D013312:Stress, Physiological / Q000187:drug effects* / Q000235:genetics; D014230:Triazoles / Q000494:pharmacology*; D014867:Water / Q000378:metabolism
chemical_list: D000975:Antioxidants; D002241:Carbohydrates; D003521:Cyclopropanes; D004573:Electrolytes; D011809:Quinones; D014230:Triazoles; D014867:Water; D002734:Chlorophyll; D008315:Malondialdehyde; C053370:paclobutrazol; D000040:Abscisic Acid; D011392:Proline; D006861:Hydrogen Peroxide; C478127:trinexapac-ethyl
keywords: Abscisic acid; Drought stress; Paclobutrazol; Perennial ryegrass; Trinexapac-ethyl