Minimal impacts on the wheat microbiome when Trichoderma gamsii T6085 is applied as a biocontrol agent to manage fusarium head blight disease

Abstract

Fusarium head blight (FHB) is a major fungal disease that causes severe yield and quality loss in wheat. Biological control can be integrated with other management strategies to control FHB. For this purpose, Trichoderma gamsii strain T6085 is a potential biocontrol agent to limit the infection of F. graminearum and F. culmorum in wheat. However, the possible impacts of T. gamsii T6085 on the broader microbiome associated with the wheat plant are not currently understood. Therefore, we identified bacteria and fungi associated with different wheat tissues, including assessment of their relative abundances and dynamics in response to the application of T6085 and over time, using amplicon sequencing. Residues of the prior year’s wheat crop and the current year’s wheat spikes were collected at multiple time points, and kernel samples were collected at harvest. DNA was extracted from the collected wheat tissues, and amplicon sequencing was performed to profile microbiomes using 16S v4 rRNA amplicons for bacteria and ITS2 amplicons for fungi. Quantitative PCR was performed to evaluate the absolute abundances of F. graminearum and T. gamsii in different wheat tissues. Disease progression was tracked visually during the growing season, revealing that FHB severity and incidence were significantly reduced when T6085 was applied to wheat spikes at anthesis. However, treatment with T6085 did not lessen the F. graminearum abundance in wheat spikes or kernels. There were substantial changes in F. graminearum abundance over time; in crop residue, pathogen abundance was highest at the initial time point and declined over time, while in wheat spikes, pathogen abundance increased significantly over time. The predominant bacterial taxa in wheat spikes and kernels were Pseudomonas, Enterobacter, and Pantoea, while Alternaria and Fusarium were the dominant fungal groups. Although the microbiome structure changed substantially over time, there were no community-scale rearrangements due to the T6085 treatment. The work suggests several other taxa that could be explored as potential biocontrol agents to integrate with T6085 treatment. However, the timing and the type of T6085 application need to be improved to give more advantages for T6085 to colonize and reduce the F. graminearum inoculum in the field.

Containment of Fusarium culmorum and Its Mycotoxins in Various Biological Systems by Antagonistic Trichoderma and Clonostachys Strains

“…It can be assumed that an increase in biomass (although unfavorable from an economic point of view) indicates greater plant vigor and, consequently, plant health. Moreover, as evidenced by the previously cited literature reports [ 58 , 73 , 74 ], the effect of inoculation with Trichoderma fungi in field conditions could depend on weather conditions. According to locally monitored data (2017/2018 in Cerekwica, Western Poland; GPS coordinates: 52°5′ N, 16°7′ E), the temperature during the sowing of winter wheat Legenda in the second half of September 2017 was T max 17 °C and T min 13 °C, with precipitation of 3 mm.…”

“…Previous studies have indicated that the effect of Trichoderma pre-inoculation is not stable over time and may depend on climatic conditions. Sarocco et al [ 73 ] and Alukumbura et al [ 74 ] described the variable effects of the pre-inoculation of T. gamsii T6085 wheat ears on the frequency and severity of FHB caused by F. graminearum and wheat agronomic parameters. Based on quantitative analysis, Alukumbura et al [ 74 ] noted that pre-inoculation with T. gamsii T6085 did not limit the abundance of F. graminearum in wheat ears/kernels, although disease rates were reduced.…”

“…Sarocco et al [ 73 ] and Alukumbura et al [ 74 ] described the variable effects of the pre-inoculation of T. gamsii T6085 wheat ears on the frequency and severity of FHB caused by F. graminearum and wheat agronomic parameters. Based on quantitative analysis, Alukumbura et al [ 74 ] noted that pre-inoculation with T. gamsii T6085 did not limit the abundance of F. graminearum in wheat ears/kernels, although disease rates were reduced. Meanwhile, Gimeno et al [ 51 ] analyzed the effect of C. rosea on reducing the severity of wheat disease caused by F. graminearum .…”

Trichoderma gamsiiT6085, a biocontrol agent of Fusarium head blight, modulates biocontrol‐relevant defence genes expression in wheat

“…Demonstrating the modulation of defence-related genes in wheat-both at localized and systemic level-not only when T6085 is inoculated alone but also when applied prior to infection with the pathogen, means this isolate can profit from all the mechanisms of action, direct and indirect, of a commercial biocontrol agent (Collinge et al, 2022). In light of these new results, it is possible to assert that the effect already observed under field conditions (Alukumbura et al, 2022;Sarrocco, 2023) in terms of disease control is due to the ability of T6085 to modulate a defence response in its plant host.…”

“…Recently, the use of beneficial bacteria, yeasts and filamentous fungi has been reported to reduce FHB both in terms of disease control and prevention of mycotoxin contamination (Sarrocco, Mauro, et al, 2019), with endophytes actually considered as the last frontier in the management of FHB on cereals (Rojas et al, 2020). Within this context, the ability of Trichoderma gamsii T6085 to control FHB symptoms (Alukumbura et al, 2022;Vicente et al, 2020) and mycotoxin accumulation, coupled with mycoparasitic, antagonistic and competitive activities against Fusarium graminearum, one of the main causal agents of FHB on wheat, have been investigated for a long time (Matarese et al, 2012;Sarrocco et al, 2013;Sarrocco, Valenti, et al, 2019). The ability of this isolate to compete for cultural debris possession and to endophytically colonize wheat roots and spikes has been demonstrated (Sarrocco et al, 2013(Sarrocco et al, , 2021, while the plant response to T6085 colonization has not been fully investigated yet.…”