# Puccinia triticina and Salicylic Acid Stimulate Resistance Responses in Triticum aestivum Against Diuraphis noxia Infestation

## TL;DR

This study shows that using a specific wheat rust isolate and salicylic acid can boost wheat's natural defenses against aphid infestations, reducing damage and improving antioxidant activity.

## Contribution

The novel finding is that avirulent Puccinia triticina isolate UVPt13 and salicylic acid priming effectively enhance wheat resistance to Russian wheat aphid.

## Key findings

- Priming with UVPt13 and salicylic acid significantly reduced leaf damage caused by Russian wheat aphid.
- UVPt13 and salicylic acid increased antioxidant enzyme activities like superoxide dismutase and peroxidase.
- Catalase activity decreased more in UVPt13-treated plants compared to other treatments.

## Abstract

Wheat plants encounter both biotic and abiotic pressure in their surroundings. Among the biotic stress factors, the Russian wheat aphid (RWA: Diuraphis noxia Kurdjumov) decreases grain yield and quality. The current RWA control strategies, including resistance breeding and the application of aphicides, are outpaced and potentially environmentally harmful. Alternatively, priming can stimulate defence responses to RWA infestation. This study investigated the priming potential of two priming agents, avirulent Puccinia triticina (Pt) isolates and salicylic acid (SA), against RWA infestation. The priming effect of Pt isolates and SA in reducing RWA-induced leaf damage and increased antioxidant activities is an indication of defence responses. Selected South African wheat cultivars and Lesotho landraces, grown under greenhouse conditions, were inoculated with Pt isolates (UVPt13: avirulent, UVPt26: virulent) and treated with SA at the seedling or booting stages. The leaf damage rating score was used for phenotyping. The antioxidant-mediated defence responses were evaluated in three selected cultivars for further priming investigation. Our results revealed that the priming agents significantly reduced the leaf damage in most cultivars at both growth stages, and UVPt13 and SA priming significantly (p ≤ 0.05) increased superoxide dismutase, peroxidase, and ascorbate peroxidase activities. However, catalase activity exhibited a more pronounced decline in plants treated with the UVPt13 isolate. The Pt isolate priming was more efficient than the SA application. However, it is crucial to investigate the potential of effectors from the avirulent Pt isolate to prime wheat plants for resistance against RWA infestation. This could contribute to developing strategies to enhance crop protection and relieve pest pressure in wheat production.