Sucrose Promotes the Proliferation and Differentiation of Callus by Regulating ROS Intensity in Agapanthus praecox

Abstract

The proliferation and differentiation of callus is the foundation for plant regeneration and propagation. The type of carbon sources in the medium significantly influences the efficacy of callus proliferation and differentiation in plants in vitro. Our study performed transcriptomic and physiological analyses utilizing sucrose, glucose, and maltose to understand the physiological and molecular characteristics of the proliferation and differentiation potential affected by carbon sources in Agapanthus praecox. Differentially expressed genes were notably associated with plant hormone signal transduction, glycolysis/gluconeogenesis, and MAPK signaling in the proliferation and differentiation of callus. The physiological indicators suggest glucose enhanced both callus and cell size by increasing endogenous indole-3-acetic acid (IAA), cytokinin, brassinosteroid, gibberellin (GAs), starch, and glucose levels, while concurrently reducing levels of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) and hydroxyl radical (·OH). Conversely, sucrose treatment promoted differentiation potential by elevating IAA oxidase activity alongside stress-related hormones such as abscisic acid and ethylene levels. Additionally, sucrose treatment led to increased accumulation of sucrose, fructose, H2O2, and ·OH within the callus tissue. Furthermore, sucrose influenced the regenerative capacity by modulating glycometabolism and osmoregulation. Our study posits that glucose facilitates callus proliferation via diminished ROS intensity while sucrose promotes callus differentiation by maintaining moderate ROS levels. Altogether, our results suggest carbon sources affected the regenerative capabilities of callus by regulating plant hormone signal and ROS intensity in A. praecox.