Effects of 24‐epibrassinolide on plant growth, osmotic regulation and ion homeostasis of salt‐stressed canola

Abstract

This study evaluated effects of foliar spraying 24-epibrassinoide (24-EBL) on the growth of salt-stressed canola. Seedlings at the four-leaf stage were treated with 150 mM NaCl and different concentrations of 24-EBL (10(-6), 10(-8), 10(-10), 10(-12) M) for 15 days. A concentration of 10(-10) M 24-EBL was chosen as optimal and used in a subsequent experiment on plant biomass and leaf water potential parameters. The results showed that 24-EBL mainly promoted shoot growth of salt-stressed plants and also ameliorated leaf water status. Foliar spraying of salt-stressed canola with 24-EBL increased osmotic adjustment ability in all organs, especially in younger leaves and roots. This was mainly due to an increase of free amino acid content in upper leaves, soluble sugars in middle leaves, organic acids and proline in lower leaves, all of these compounds in roots, as well as essential inorganic ions. Na(+) and Cl(-) sharply increased in different organs under salt stress, and 24-EBL reduced their accumulation. 24-EBL improved the uptake of K(+), Ca(2+), Mg(2+) and NO3(-) in roots, which were mainly transported to upper leaves, while NO3(-) was mainly transported to middle leaves. Thus, 24-EBL improvements in ion homeostasis of K(+)/Na(+), Ca(2+)/Na(+), Mg(2+)/Na(+) and NO3(-)/Cl(-), especially in younger leaves and roots, could be explained. As most important parts, younger leaves and roots were the main organs protected by 24-EBL via improvement in osmotic adjustment ability and ion homeostasis. Further, physiological status of growth of salt-stressed canola was ameliorated after 24-EBL treatment.

The role of 24-epibrassinolide in the regulation of photosynthetic characteristics and nitrogen metabolism of tomato seedlings under a combined low temperature and weak light stress

“…EBR also affects other developmental processes, such as the germination of seeds, root and stem growth, fruit development, senescence, abscission, and maturation (Müssig, 2005;Fariduddin et al, 2014). Many studies have shown that EBR could confer resistance to plants against various abiotic and biotic stresses, such as drought stress (Yuan et al, 2010), mixed salinity-temperature stress (Hayat et al, 2010), heat stress (Kagale et al, 2007), salt stress (Liu et al, 2014), cadmium stress (Hasan et al, 2011), phenanthrene stress (Ahammed et al, 2013), and Ca(NO 3 ) 2 stress (Yuan et al, 2012). Recently, several studies demonstrated that foliar application of EBR could enhance plant tolerance to different stresses via improving photosynthetic capacity, mainly owing to an increase in the chlorophyll (Chl) content, and the up-regulation in the expression levels of various oxidative stress marker genes (Choudhary et al, 2012;Yuan et al, 2012).…”

Regulation of 2,4-epibrassinolide on mineral nutrient uptake and ion distribution in Ca(NO3)2 stressed cucumber plants

“…Wang et al (2012) found that BRs are likely to play a negative role in regulating Fe-deficiency-induced ferric reductase activity and Fe translocation from roots to shoots in cucumber exposure in a Fe-deficient medium. Under NaCl stress, EBL reduced the accumulation of Na + and Cl − in shoot and root of canola, and improved the ion homeostasis of K + /Na + , Ca 2+ /Na + , Mg 2+ /Na + and NO 3 − /Cl − in younger leaves and roots (Liu et al, 2014). However, the mechanism of how BRs regulate ion distribution still needs further research.…”

Transcriptome Analysis of Pepper (Capsicum annuum) Revealed a Role of 24-Epibrassinolide in Response to Chilling

“…Under stress, plants produce a number of phytohormones, such as salicylic acid (SA), brassinosteroids (BRs), and abscisic acid (ABA), which play a critical role in the perception of external signals and the activation of defense mechanism within plants. Brassinosteroids, a group of naturally occurring plant steroids, have been shown to provide positive effects on the regulation of plant growth and a broad spectrum of physiological responses to abiotic stresses, such as high and low temperature stress (Mazorra et al, 2002; Bajguz, 2009), drought (Yuan et al, 2010), and salinity injury (Liu et al, 2014). For example, BRs increase thermotolerance of plants by inducing heat shock protein synthesis and gene expression for heat tolerance (Dhaubhadel et al, 2002; Dhaubhadel and Krishna, 2008).…”