Antagonistic Activity of Trichoderma spp. Against Fusarium oxysporum in Rhizosphere of Radix pseudostellariae Triggers the Expression of Host Defense Genes and Improves Its Growth Under Long-Term Monoculture System

Abstract

Under consecutive monoculture, the abundance of pathogenic fungi, such as Fusarium oxysporum in the rhizosphere of Radix pseudostellariae, negatively affects the yield and quality of the plant. Therefore, it is pertinent to explore the role of antagonistic fungi for the management of fungal pathogens such as F. oxysporum. Our PCR-denatured gradient gel electrophoresis (DGGE) results revealed that the diversity of Trichoderma spp. was significantly declined due to extended monoculture. Similarly, quantitative PCR analysis showed a decline in Trichoderma spp., whereas a significant increase was observed in F. oxysporum. Furthermore, seven Trichoderma isolates from the R. pseudostellariae rhizosphere were identified and evaluated in vitro for their potentiality to antagonize F. oxysporum. The highest and lowest percentage of inhibition (PI) observed among these isolates were 47.91 and 16.67%, respectively. In in vivo assays, the R. pseudostellariae treated with four Trichoderma isolates, having PI > 30%, was used to evaluate the biocontrol efficiency against F. oxysporum in which T. harzianum ZC51 enhanced the growth of the plant without displaying any disease symptoms. Furthermore, the expression of eight defense-related genes of R. pseudostellariae in response to a combination of F. oxysporum and T. harzianum ZC51 treatment was checked, and most of these defense genes were found to be upregulated. In conclusion, this study reveals that the extended monoculture of R. pseudostellariae could alter the Trichoderma communities in the plant rhizosphere leading to relatively low level of antagonistic microorganisms. However, T. harzianum ZC51 could inhibit the pathogenic F. oxysporum and induce the expression of R. pseudostellariae defense genes. Hence, T. harzianum ZC51 improves the plant resistance and reduces the growth inhibitory effect of consecutive monoculture problem.

Changes in the Density and Composition of Rhizosphere Pathogenic Fusarium and Beneficial Trichoderma Contributing to Reduced Root Rot of Intercropped Soybean

“…From this point of view, Trichoderma communities are a important group in response to maize-soybean relay strip intercropping as compared to soybean monoculture. This is also proved in previous study by Chen et al (Chen et al 2021). That expanded monoculture of R. peseudostellariae altered Trhicoderma communities in the plant rhizosphere leading to relatively low level of antogonistic microorganisms, and among them T. harzianum ZC51 could inhibit the pathogenic F. oxysporum and induce the expression of defense genes.…”

“…In the Radix pseudostellariae rhizosphere, the consecutive monoculture increases the abundance of the pathogenic F. oxysporum but decreases Trichoderma spp. (Chen et al 2021). Recently, a maize-soybean relay strip intercropping is widely practised in Southwest China, and this cropping pattern is characterized by two-row maize plants strip intercropped with two-to-four rows of soybean which has positive effects on increasing the land equivalent ratio (Yang et al 2015), improving the soil nutrients and microbe structure (Chen et al 2017;Song et al 2020Song et al ,2021, reducing weeds and diseases in the eld ( Chang et al 2020;Su et al 2018) and increasing crop yield (Du et al 2018;Liu et al 2017) as compared to soybean monoculture.…”

In Vitro Study of Biocontrol Potential of Rhizospheric Microorganisms Against Fusarium Oxysporum F.SP. Albedinis

“…Confrontation methods: Pathogens-antagonistic fungi confrontation: To evaluate the effect and ability of antagonistic fungi to suppress mycelial growth of the 4 pathogenic strains of Foa (E22, SA6, SG10 and B10 / 08), direct confrontation method using the in vitro cocultivation assay were carried (Fig. 1A), according to Howell (2003), Sidaoui et al (2018), Tian et al (2020 and Chen et al (2021) with slight modifications. In this test, two discs of 0.5 mm of diameter, one from 7 days aged culture of Foa, and another from antagonist, were deposited in Petri dishes containing 15 mL of PDA medium, which were placed opposite to each other in the Petri dishes on the same diagonal line with a distance of 1cm from the edge.…”

“…against F. moniliforme. In fact, several strains of the genera Penicillium and Alternaria have been isolated and reported as potentially active agents in the biological control of certain plant diseases (Pecundo et al, 2021;Chen et al, 2021). In addition, a large part of the species of the genus Penicillium has several action mechanisms for plant protection (production of antibiotics, induction of resistance and the establishment of mycoparasitic interactions) against pathogenic microorganisms (Nicoletti and De Stefano, 2012).…”

Pathogen-Mediated Assembly of Plant-Beneficial Bacteria to Alleviate Fusarium Wilt in Pseudostellaria heterophylla

“…Continuous monoculture of traditional herbal medicines often leads to soil-borne disease. Like other traditional herbal medicines and crops, P. heterophylla is replanted on the same field with asexual propagation for many years, resulting in the high incidence of Fusarium wilt (FW), a replant disease caused by infection with Fusarium oxysporum ( Wu et al, 2016b , 2020a , 2021 ; Chen et al, 2021 ). FW is characterized by damping-off, wilting, and dry brown rot and is a disastrous disease in many crops (i.e., wheat, cotton, and chickpea) and fruits (i.e., banana, melon, and watermelon).…”