Seed Treatment with Trichoderma longibrachiatum T6 Promotes Wheat Seedling Growth under NaCl Stress Through Activating the Enzymatic and Nonenzymatic Antioxidant Defense Systems.

Shuwu Zhang,Bingliang Xu,Yantai Gan

doi:10.3390/ijms20153729

Abstract

Salt stress is one of the major abiotic stresses limiting crop growth and productivity worldwide. Species of Trichoderma are widely recognized for their bio-control abilities, but little information is regarding to the ability and mechanisms of their promoting plant growth and enhancing plant tolerance to different levels of salt stress. Hence, we determined (i) the role of Trichoderma longibrachiatum T6 (TL-6) in promoting wheat (Triticum aestivum L.) seed germination and seedling growth under different levels of salt stress, and (ii) the mechanisms responsible for the enhanced tolerance of wheat to salt stress by TL-6. Wheat seeds treated with or without TL-6 were grown under different levels of salt stress in controlled environmental conditions. As such, the TL-6 treatments promoted seed germination and increased the shoot and root weights of wheat seedlings under both non-stress and salt-stress conditions. Wheat seedlings with TL-6 treatments under different levels of NaCl stress increased proline content by an average of 11%, ascorbate 15%, and glutathione 28%; and decreased the contents of malondialdehyde (MDA) by an average of 19% and hydrogen peroxide (H2O2) 13%. The TL-6 treatments induced the transcriptional level of reactive oxygen species (ROS) scavenging enzymes, leading to the increases of glutathione s-transferase (GST) by an average of 17%, glutathione peroxidase (GPX) 16%, ascorbate peroxidase (APX) 17%, glutathione reductase (GR) 18%, dehydroascorbate reductase (DHAR) 5%. Our results indicate that the beneficial strain of TL-6 effectively scavenged ROS under NaCl stress through modulating the activity of ROS scavenging enzymes, regulating the transcriptional levels of ROS scavenging enzyme gene expression, and enhancing the nonenzymatic antioxidants in wheat seedling in response to salt stress. Our present study provides a new insight into the mechanisms of TL-6 can activate the enzymatic and nonenzymatic antioxidant defense systems and enhance wheat seedling tolerance to different levels of salt stress at physiological, biochemical and molecular levels.

Highlights

Salinity stress is one of the serious abiotic stresses and global environmental problems that adversely affecting and limiting the plant growth and yield, agricultural production and environmental health worldwide [1,2]
Compared with wheat seeds that were soaked with sterile water, the seeds treated with the strain of TL-6 increased the germination rate by an average of 6%, germination potential 8%, and germination index 10%, across the three NaCl treatments (0, 10 and 20 mg mL−1)
Trichoderma spp. are common and free-living fungi that are well researched for their growth promoting and biocontrol properties [19]

Summary

Introduction

Salinity stress is one of the serious abiotic stresses and global environmental problems that adversely affecting and limiting the plant growth and yield, agricultural production and environmental health worldwide [1,2]. It is predicted that more than 20% of global agricultural production was affected [5] by salinity worldwide. In order to alleviate the adverse effects caused by salt stress, many researchers have tried to breed and develop salt-tolerant plant cultivars to alleviate this situation. It is worthwhile to explore the question of how to mitigate the adverse effects of salt stress, and enhance plant tolerance to salt stress, and eventually increase the plant yields

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Conclusion