Priming of plant innate immunity by β-aminobutyric acid improved barley resistance to grain aphid (Sitobion avenae).

The present study explored the effects of β-aminobutyric acid (BABA) on wheat (Triticum aestivum L.) in the context of grain aphid infestation, aiming to promote crop resilience to biotic stress. Wheat seeds were treated with BABA at 50 µM before being cultivated in a controlled environment, revealing significant improvements in the physiological and biochemical responses of the treated plants, particularly under aphid pressure.  BABA treatment led to substantial increases in photosynthetic efficiency and antioxidant defenses, with a remarkable 39% enhancement in photosynthetic rates compared to untreated infested plants. The investigation into amino acid composition revealed significant following BABA application, where some amino acids such as proline, phenylalanine, asparagine and glutamine levels rose particularly in infested plants. These shifts in amino acid profile acted as precursors to the enhanced antioxidant metabolites, which resulted in increased content of antioxidant molecules in BABA-treated plants, with flavonoids rising by 24%, polyphenols by 58% and tocopherols by 55% compared to untreated plants under aphid infestation. Moreover, studying anthocyanin metabolism, as an important flavonoid pigment, helped to understand how variations in phenylalanine amino acid content can increase the production of anthocyanins in BABA-treated plants under both infestation (+ 296%) and non-infestation conditions (+ 90%). Furthermore, BABA-treated plants exhibited a 47% increase in fresh weight under infestation conditions. These results underscore BABA’s potential as a biostimulant that promotes healthier physiological responses in wheat, positioning it as a valuable tool in sustainable pest management strategies.