Phytohormone-based strategies for improving wheat tolerance to drought and Russian wheat aphid infestation

Overview

Drought stress and Russian wheat aphid (RWA) infestation are persistent threats to global wheat production, and the interaction between these two stresses remains poorly understood at the hormonal level. This research program investigates how three key phytohormones—jasmonic acid (JA), salicylic acid (SA), and abscisic acid (ABA)—respond to combined drought and aphid pressure in wheat cultivars with differing drought tolerance and aphid resistance profiles. By correlating phytohormone levels with antioxidative capacity and osmolyte concentration, the project seeks to identify biochemical markers of combined-stress tolerance. A secondary objective evaluates whether exogenous application of specific hormones can improve growth parameters and reduce RWA damage, offering a potential agronomic intervention for growers facing both stressors.

The findings are expected to support the development of more resilient wheat cultivars and inform integrated pest and water management strategies, which are increasingly relevant for food security in semi-arid production regions.

Technical specifications

Research design:

• A completely randomised greenhouse trial with three replications in a split-split plot arrangement
• Main plots: infestation levels (control versus RWA-infested)
• Subplots: drought levels (0%, 30%, and 50% field capacity)
• Sub-sub plots: four wheat cultivars selected for contrasting drought tolerance and aphid resistance

Plant materials and growing conditions:

• Growth substrate: air-dried red soil (Bainsvlei Amalia 2300) mixed with peat at a 1:1 ratio
• Experimental unit: a single pot per treatment combination
• Location: greenhouse facilities at the Department of Plant Sciences, University of the Free State

Measurements and analyses:

• Quantification of JA, SA, and ABA levels in response to drought, aphid infestation, and their combination
• Assessment of antioxidative capacity and osmolyte concentration as indicators of stress tolerance
• Evaluation of growth parameters following exogenous application of specific phytohormones
• Correlation analyses linking hormone profiles to RWA resistance across cultivars

Technology readiness level

This is an early-stage fundamental research program at Technology Readiness Level 1–2 (basic research and proof-of-concept formulation). The hypothesis has been developed based on existing literature on phytohormone signalling and plant stress biology, but the planned greenhouse validation experiments have not yet been executed. Future validation will generate the first empirical dataset linking JA, SA, and ABA dynamics to combined drought and RWA stress in the selected wheat cultivars. Outputs are expected to inform downstream cultivar screening pipelines and potential field-scale trials rather than deliver a market-ready product in the near term.