Penicillium simplicissimum and Trichoderma asperellum counteract the challenge of Puccinia striiformis f. sp. tritici in wheat plants

Abstract

Abstract Background Yellow (stripe) rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an economic disease of wheat. Growth-promoting fungi (GPF) such as Trichoderma asperellum and Penicillium simplicissimum have been investigated for their potential to control yellow rust and their involvement in gene expression of four PR proteins for all-stage resistance. Results Wheat plants (cv. Sids-12) treated individually with each of the biocontrol agents, P. simplicissimum and T. asperellum, at 24 and 48 hpi showed a resistance response (infection type = 2) to yellow rust, compared to the non-treated plants, which showed highly susceptible response (infection type = 9). Both biocontrol agents induced resistance against yellow rust on wheat plants, exhibiting a moderate resistance (10 MR) and reduced the colony size of Pst (0.6 mm2). Moreover, P. simplicissimum and T. asperellum increased (P ≤ 0.05) the grain yields of wheat plants infected with Pst. Scanning electron microscope (SEM) of yellow rust infected wheat leaves treated with P. simplicissimum and T. asperellum at 24 and 48 hpi showed hyperparasitism on Pst urediniospores and inhibition of the spore germination. Expressions of pathogenesis-related (PR) protein genes, PR1, PR2, PR3 and PR4 were higher in wheat plants treated with both biocontrol agents than the non-treated checks. Conclusion P. simplicissimum and T. asperellum exhibited biocontrol potential against yellow rust disease caused by P. striiformis f. sp. tritici (Pst) on wheat plants. It was found that wheat defence mechanism against Pst was activated by a high expression of PR protein genes induced by both biocontrol agents.