Peroxidase and β-1,3-glucanase synergistic functions strengthen plant cell wall and protect wheat against Diuraphis noxia infestation
Siphephelo N.N. Zondo, Mpho S. Mafa
Abstract
MAIN CONCLUSION: Peroxidase and β-1,3-glucanase functions improved cell wall lignification and reduced callose during plant-pest interactions. Lignification effectively strengthens the cell wall, whilst callose deposition weakens and makes the cell wall porous. In the past two decades, studies have demonstrated that wheat infested with Russian wheat aphid (RWA) changes its biochemical and physiological metabolic functions. These changes include increased β-1,3-glucanases and peroxidase (POD) activity in the resistant cultivars. The POD activity is associated with reactive oxygen species production or quenching. However, the β-1,3-glucanase physiological function is not fully understood. Here, we reviewed the cell wall-related roles of POD and β-1,3-glucanase and their implication on plant biochemical and physiological processes during biotic stress, particularly RWA infestation. We demonstrate that β-1,3-glucanases cell wall isozymes regulate callose accumulation in the resistant wheat cultivar, improving the transport of signalling molecules within RWA-infested plants. In other plant systems, the β-1,3-glucanases' activity is linked with the formation of the non-penetration papillae (NPP), whilst the POD is associated with the lignification of the NPP. These cell wall modifications deter RWA feeding and improve plant health. In addition, there is increasing evidence that β-1,3-glucan oligosaccharides trigger pattern immune responses during the plant-pest/pathogen interaction, indicating that upregulation of β-1,3-glucanases activity in resistant cultivars can induce this type of defence response during RWA-wheat interaction. We conclude that POD and β-1,3-glucanases' activities are central to cell wall reinforcements and induction of immune responses in the resistant wheat infested with RWA. Therefore, this work highlights the synergistic effects of POD and β-1,3-glucanases in regulating cell wall modification that strengthens the cell wall, making it impenetrable to pest (including RWA) attacks.