5-Aminolevulinic acid could enhance the salinity tolerance by alleviating oxidative damages in Salvia miltiorrhiza

Xin Li,Ullah Najeeb,Jianyao Shou,Jianmin Pan,Zhuoni Hou,Ling Xu,Juanjuan Li,Faisal Islam,Yebo Qin

doi:10.1590/fst.103121

Abstract

S. miltiorrhiza is a Chinese medicinal plant that is widely cultivated. The root growth in S. miltiorrhiza are inhibited by soil salinity. Here we investigated the capability of a plant growth regulator, 5-ALA to promote the growth of S. miltiorrhiza under different salt stresses. Five-month old S. miltiorrhiza roots were uniformly irrigated with different levels of salt solution i.e. 0, 100, 200 mM NaCl. After 3 days of treatment, salt-treated S. miltiorrhiza plants were sprayed with different concentrations of ALA (0, 10 mg L-1, 20 mg L-1) on the leaves and cultured for another 7 days. Results revealed that ALA treated plants produced significantly higher biomass by sustaining leaf chlorophyll content under salt stressed. 10 mg L-1 ALA significantly up-regulated antioxidant enzymes activities under studied salinity treatments. Positive effects of ALA on antioxidant defense systems were also supported by a significant increase in the expression of SOD isoenzymes genes (CSD1, FSD1 and MSD2), defense response genes (DXS1, C4H, GGPPS) and stress-related gene (MYB36 , MYB39) of ALA treated plants. This study suggested that ALA can protect S. miltiorrhiza from salinity induced oxidative stress and injury by promoting antioxidant defense system, boosting secondary metabolic pathways and protecting photosynthetic pigments.

Highlights

Salinity, drought, cold, and extreme temperature are the major abiotic stresses which restrain the growth and development of plants (Guo et al, 2018)
In the absence of aminolevulinic acid (ALA) treatment, S. miltiorrhiza plants experienced a significant reduction in plant height, root length and biomass production under salinity treatments (Table 2). 10 mg L-1ALA significantly improved the growth and increased the fresh weights of leaves and roots of S. miltiorrhiza under different salinity stresses
Dry weight of roots under the treatment of 20 mg L-1 ALA + 200mM NaCl declined 31.91%, as compared to the 200mM NaCl treatment alone. This suggests that selection of an optimum level of ALA i.e. 10 mg L-1 is crucial for protecting S. miltiorrhiza plants from salinity stress injury

Summary

Introduction

Drought, cold, and extreme temperature are the major abiotic stresses which restrain the growth and development of plants (Guo et al, 2018). Soil salinity has become a major yield limiting factor for cultivated crops in many parts of the world (Khan et al, 2019). Saline soils occurred on the eastern coastline of China (Gengmao et al, 2014). Salinity stressed plants might capture these enhanced ROS by modifying the activities of antioxidant enzymes, for instance POD, APX and SOD (Gengmao et al, 2014). Some plants i.e. sunflowers and some medicinal plants have negative effects under saline soils (Liu & Shi, 2010; Guo et al, 2018). Investigation of salt tolerance mechanisms of these plants are very important for the further salinity tolerance breeding

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