Effects of 6-Benzyladenine, γ-Aminobutyric Acid, and Nitric Oxide on Plant Growth, Photochemical Efficiency, and Ion Accumulation of Perennial Ryegrass Cultivars to Salinity Stress

Abstract

<jats:p>Plant growth regulators (PGRs) can mediate plant response to salinity stress. Perennial ryegrass (<jats:italic>Lolium perenne</jats:italic>) cultivars of BrightStar SLT, Catalina, Inspire, and SR4660ST were exposed to 0, 100, or 200 m<jats:sc>m</jats:sc> NaCl for 14 d. 6-benzyladenine (6-BA, 10 µ<jats:sc>m</jats:sc>), γ-aminobutyric acid (GABA, 500 µ<jats:sc>m</jats:sc>), nitric oxide (NO, 200 µ<jats:sc>m</jats:sc>), and H<jats:sub>2</jats:sub>O were applied to the foliage every day for 3 days before stress and then every 2 days during salinity stress. Averaged across the four cultivars, a foliar spray of NO increased leaf fresh weight (FW) and dry weight (DW) at 0 m<jats:sc>m</jats:sc> NaCl, whereas application of 6-BA increased DW and GABA reduced Na<jats:sup>+</jats:sup> concentration at 100 m<jats:sc>m</jats:sc> NaCl, compared with H<jats:sub>2</jats:sub>O application. Plants treated with 6-BA, GABA, and NO had less chlorotic and necrotic leaf tissue than plants treated with H<jats:sub>2</jats:sub>O at 200 m<jats:sc>m</jats:sc> NaCl. Spray of 6-BA and NO increased FW and DW, but application of all three PGRs maintained higher leaf photochemical efficiency and lower leaf Na<jats:sup>+</jats:sup> concentration compared with H<jats:sub>2</jats:sub>O treatment at 200 m<jats:sc>m</jats:sc> NaCl. Across salinity and PGR treatments, ‘Catalina’ exhibited higher plant height than the ‘Inspire’ and SR4660ST, and SR4660ST had relatively higher Na<jats:sup>+</jats:sup> concentration than ‘Catalina’ but not ‘BrightStar SLT’ and ‘Inspire’. The results demonstrate that 6-BA, GABA, and NO ameliorated salinity tolerance of perennial ryegrass by improving growth and photochemical efficiency or reducing Na<jats:sup>+</jats:sup> accumulation.</jats:p>

Effects of Exogenous Sodium Nitroprusside Spraying on Physiological Characteristics of Soybean Leaves at the Flowering Stage under Drought Stress

“…In response to NO, CAT activity showed a gradual increase over time [40]. Ji et al [41] Sprayed NO donors on the leaves of cotton to increase the biosynthesis of the CAT gene in cotton under normal growth conditions and thereby increase CAT activity, consistent with the results of this experiment. To sum up, spraying SNP increased the activity of antioxidant enzymes in soybean and enhanced the ability of soybean to cope with drought stress.…”

The Role of Nitric Oxide in Plant Responses to Salt Stress

“…A previous report showed that CK and NO regulated the salt tolerance of perennial ryegrass by reducing Na + accumulation and improving growth and photochemical efficiency [ 90 ]. Other researchers demonstrated that the foliar application of SNP increased the expression of CK biosynthesis genes (e.g., ZR , IPA , and IPT1 ) in cotton, suggesting that NO promotes CK biosynthesis, which delays salt-induced leaf senescence [ 91 ].…”

Exogenous 6-Benzyladenine Improves Waterlogging Tolerance in Maize Seedlings by Mitigating Oxidative Stress and Upregulating the Ascorbate-Glutathione Cycle

“…Thus, supplemental 6-BA allows plants to overcome the negative effects of various types of abiotic stress. Treatment with 6-BA has been shown to enhance photochemical efficiency, increase growth, and reduce Na + accumulation in ryegrass in a saline environment; thus effectively preventing the inhibition of growth in plants experiencing salt stress (Ji et al, 2019). The exogenous application of 6-BA could significantly reduce toxicity caused by cadmium (Cd) and uranium (U) on rapeseed, subsequently reducing malondialdehyde (MDA) and H 2 O 2 levels and increasing antioxidant levels (Chen et al, 2020).…”

“…However, to the best of our knowledge, no study has investigated the role of 6-BA-induced tolerance to waterlogging stress in waxy corn. Based on previous studies, which have explored the role of 6-BA in other plants undergoing different forms of stress (Ji et al, 2019;Chen et al, 2020;Hu et al, 2020;Li et al, 2020;Wang X. Y. et al, 2020), we hypothesized that 6-BA scavenges ROS by the promotion of the AsA-GSH cycle system and alleviates the adverse effects of oxidative damage from waterlogging stress in waxy corn seedlings, thereby enhancing tolerance to waterlogging in waxy corn seedlings. Hence, the effect of leaf-sprayed 6-BA in two genotypes of waxy corn seedlings when waterlogged was investigated by comparing morphology, ROS metabolism, cell stability, and the AsA-GSH cycle to verify whether 6-BA prevents oxidative damage from waterlogging stress in waxy corn seedlings.…”