Antioxidative metabolism in sugarcane (Poaceae) varieties subjected to water and saline stress

Marciana B De Morais,Terezinha R Camara,Cynthia C De Albuquerque,Cláudia Ulisses,Ricardo A Azevedo,Lilia Willadino

doi:10.1590/1807-1929/agriambi.v24n11p776-782

Abstract

ABSTRACT This study aimed to identify the antioxidant responses of sugarcane (Saccharum spp.) varieties subjected to water and saline stress. Sugarcane seedlings of six different varieties obtained through micropropagation were subjected to either water or saline stress, or a combination of water + saline stress. The study was carried out in May 2012, in a greenhouse at the Universidade Federal Rural de Pernambuco (UFRPE). The experimental design was randomized, with treatments arranged in a 6 × 4 factorial scheme (six varieties and four treatments), and four replicates. Lipid peroxidation, hydrogen peroxide (H2O2) concentrations, and relative water content (RWC) were evaluated. Furthermore, we evaluated the plants’ antioxidative defense systems by measuring the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). The sugarcane varieties had higher lipid peroxidation and/or higher H2O2 concentrations when subjected to the combined water + saline stress. The antioxidant enzymes responded to the water and saline stress treatments differently depending on the sugarcane variety. However, under combined saline + water stress conditions, the enzymes may have become inactivated, which indicates that the response to the combined water + saline stress was different from the sum of the responses to only water stress or only saline stress. High concentrations of malondialdehyde (MDA) associated with low RWC may be an effective indicator of multiple stress sensitivity in sugarcane varieties. The RB99395 and RB867515 sugarcane varieties responded more efficiently to environmental stress, and maintained their cell water content when subjected to either water or saline stress.

Highlights

Sugarcane (Saccharum spp.) cultivation in the Northeastern region of Brazil has been expanding to semi-arid regions, exposing the crop to an environment more prone to the combination of abiotic stressors, such as salinity of water and soil, and water deficits during certain stages of sugarcane development, or even throughout the plant life cycle (Lyra et al, 2012)
Under saline stress (T3), the RWC values remained above 75%, indicating that the sugarcane varieties experienced a moderate loss of water
The results indicate that sugarcane variety and water and saline stress treatments all significantly affected the superoxide dismutase (SOD), CAT, and ascorbate peroxidase (APX) activities (p < 0.05) (Table 3)

Summary

Introduction

Sugarcane (Saccharum spp.) cultivation in the Northeastern region of Brazil has been expanding to semi-arid regions, exposing the crop to an environment more prone to the combination of abiotic stressors, such as salinity of water and soil, and water deficits during certain stages of sugarcane development, or even throughout the plant life cycle (Lyra et al, 2012). The irregular rainfall in drier areas, combined with the high evaporative demand, limits productivity (Silva et al, 2015), and becomes a limiting factor for crop expansion. Exposure to one or several types of environmental stressors can increase the production of reactive oxygen species (ROS). Because of the multifunctional effects of ROS, cells have a defense system against ROS. This complex system uses coordinated actions, and consists of a large number of hydrophilic antioxidant compounds and enzymatic components, as well as non-enzymatic components, which prevent oxidative damage and ROS accumulation, ensuring normal cell function (Soares et al, 2019)

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