Protective and Curative Effects of Trichoderma asperelloides Ta41 on Tomato Root Rot Caused by Rhizoctonia solani Rs33

Ahmed A. Heflish,Abdulaziz A. Al-Askar,Ahmed Abdelkhalek,Said I. Behiry

doi:10.3390/agronomy11061162

Abstract

Two molecularly identified tomato isolates, Trichoderma asperelloides Ta41 and Rhizoctonia solani Rs33, were characterized and antagonistically evaluated. The dual culture technique showed that Ta41 had a high antagonistic activity of 83.33%, while a light microscope bioassay demonstrated that the Ta41 isolate over-parasitized the pathogen completely. Under greenhouse conditions, the application of Ta41 was able to promote tomato plant growth and had a significant increase in plant height, root length, and shoot fresh, shoot dry, root fresh, and root dry weight. It also improved chlorophyll content and total phenol content significantly, both in protective and in curative treatments. The protective treatment assay exhibited the lowest disease index (16.00%), while the curative treatment showed a disease index of 33.33%. At 20 days post-inoculation, significant increases in the relative expression levels of four defense-related genes (PR-1, PR-2, PR-3, and CHS) were observed in all Ta41-treated plants when compared with the non-treated plants. Interestingly, the plants treated with Ta41 alone showed the highest expression, with relative transcriptional levels of CHS, PR-3, PR-1, and PR-2 that were, compared with the control, 3.91-, 3.13-, 2.94-, and 2.69-fold higher, respectively, and the protective treatment showed relative transcriptional levels that were 3.50-, 3.63-, 2.39-, and 2.27-fold higher, respectively. Consequently, the ability of Ta41 to promote tomato growth, suppress Rs33 growth, and induce systemic resistance supports the incorporation of Ta41 as a potential bioagent for controlling root rot disease and increasing the productivity of crops, including tomatoes.

Highlights

The tomato (Lycopersicon esculentum L.) is the second-most commonly consumed vegetable crop after the potato worldwide [1]
Recognizing the importance of screening new Trichoderma species with more potent antifungal activity for agricultural use, the current study aimed to evaluate the protective and curative activities of Trichoderma asperelloides Ta41 on tomato root rot caused by Rhizoctonia solani
10 R. solani isolated from root on rot adiseased tomato plants, most shown)

Summary

Introduction

The tomato (Lycopersicon esculentum L.) is the second-most commonly consumed vegetable crop after the potato worldwide [1]. Several pathogens can infect tomato plants and cause diseases. Among the fungal pathogens causing several diseases in tomatoes, Rhizoctonia solani is the worst fungus that could damage tomato plants and reduce the yield [4,5,6]. R. solani is a destructive soil-borne pathogen that causes severe losses in many crops worldwide. The excessive use of chemical fungicides, the most common strategy used by farmers to control R. solani, poses severe risks to human health and the environment and leads to pathogen-resistant strains. Biological control is environment-friendly and effective in managing most plant fungal pathogens. Internal transcribed spacer (ITS), RNA polymerase II subunit 2 (Rpb2), and translation elongation factor 1 alpha (Tef-1) genes are the most used molecular markers in phylogenetic analysis for the high throughput sensitive identification and characterization of Trichoderma spp. for the early screening of potential antagonists against soil-borne pathogens [11]

Methods

Results

Discussion

Conclusion