Enhancement of cucumber resistance under salt stress by 2, 4-epibrassinolide lactones

Abstract

This study investigated the effects of exogenous 2, 4-epibrassinolide lactone (EBR) on the growth, photosynthetic pigments, antioxidant defense system, ion homeostasis, MAPK cascade and key genes of SOS signaling pathway of cucumber seedlings under salt stress using cucumber “Xinchun 4” as the test material. The experiment was set up with four treatments: foliar spraying of distilled water (CK), 50 mmol.L-1 NaCl (NaCl), 50 mmol.L-1 NaCl+foliar spray of 0.02 μmol.L-1 EBR (EBR+NaCl), and 50 mmol.L-1 NaCl+foliar spray of 24 μmol.L-1 Brassinazole (BRZ) (BRZ+NaCl). The results showed that EBR+NaCl treatment significantly increased plant height, above-ground fresh weight, total root length, total root surface area, average rhizome and photosynthetic pigment content compared to NaCl treatment. Meanwhile, compared with NaCl treatment, EBR+NaCl treatment significantly increased superoxide dismutase, catalase and ascorbate peroxidase (SOD, CAT and APX) activities, significantly promoted the accumulation of osmoregulatory substances (soluble sugars and proline), and thus effectively reduced malondialdehyde (MDA) content and relative electrical conductivity of cucumber leaves. Exogenous spraying of EBR also significantly reduced Na+/K+ under NaCl stress, effectively alleviating the toxic effects of Na+ ions. In addition, exogenous EBR induced the up-regulated expression of CsMAPK3, CsMAPK4, CsMAPK6 and CsMAPK9 genes in the MAPK cascade signaling pathway and CsSOS1, CsSOS2 and CsSOS3 genes in the SOS signaling pathway to enhance salt tolerance in cucumber under NaCl stress. Therefore, exogenous spraying EBR may effectively reduce the damage of salt stress on cucumber seedlings by improving antioxidant capacity, maintaining ion homeostasis and activating salt-tolerant related signaling pathways, which might promote the growth of cucumber seedlings and the establishment of root system morphology. This study provides a reference for EBR to improve the salt tolerance of cucumber.

Demography of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) reared on elicitor‐treated tomato plants with an innovative comparison of projected population sizes and application of the multinomial theorem for population survival

“…Following herbivore damage and/or external application, MJ activates direct (defense proteins) and indirect (volatile emissions) defense mechanisms 33,[65][66][67] by activating the antioxidant system, the accumulation of defense chemicals and attracting natural enemies. 68 Jasmonic acids and their derivatives have been shown to regulate gene expression in plant defense responses. [69][70][71][72][73] Jasmonatetreated plants usually defend against herbivores and diseases.…”

“…Herbivores are considered a biotic stress to plants and different defense signaling pathways can be activated in an infested plant. Following herbivore damage and/or external application, MJ activates direct (defense proteins) and indirect (volatile emissions) defense mechanisms 33,65–67 by activating the antioxidant system, the accumulation of defense chemicals and attracting natural enemies 68 …”

Integrated Transcriptomic and Metabolomic Analysis Reveals the Mechanism of Gibberellic Acid Regulates the Growth and Flavonoid Synthesis in Phellodendron chinense Schneid Seedlings

“…The soluble sugar contents in the leaves of collected seedlings were measured according to the published literature [68]. Briefly, fresh leaves (0.1 g) were ground in a mortar containing 5 mL of 80% ethanol solution, and the grinding fluid was moved into a 10 mL centrifuge tube in an 85 • C water bath for 30 min.…”

Effects of exogenous plant regulators on growth and development of “Kyoho” grape under salt alkali stress

“…In plants, the content of redox substances is strictly regulated. In addition, it has been reported that the rate of photosynthetic activity has been significantly improved (He et al, 2022). In terms of fruit quality improvement, BR spraying at appropriate mass concentrations was able to increase the yield of sugar beet tubers but had no significant effect on total sugar content (Lv et al, 2019).…”