AUXIN RESPONSE FACTOR 1 Acts as a Positive Regulator in the Response of Poplar to Trichoderma asperellum Inoculation in Overexpressing Plants

Abstract

Numerous Trichoderma strains have been reported to be optimal biofertilizers and biocontrol agents with low production costs and environmentally friendly properties. Trichoderma spp. promote the growth and immunity of plants by multiple means. Interfering with the hormonal homeostasis in plants is the most critical strategy. However, the mechanisms underlying plants’ responses to Trichoderma remain to be further elucidated. Auxin is the most important phytohormone that regulates almost every aspect of a plant’s life, especially the trade-off between growth and defense. The AUXIN RESPONSE FACTOR (ARF) family proteins are key players in auxin signaling. We studied the responses and functions of the PdPapARF1 gene in a hybrid poplar during its interaction with beneficial T. asperellum strains using transformed poplar plants with PdPapARF1 overexpression (on transcription level in this study). We report that PdPapARF1 is a positive regulator for promoting poplar growth and defense responses, as does T. asperellum inoculation. PdPapARF1 also turned out to be a positive stimulator of adventitious root formation. Particularly, the overexpression of PdPapARF1 induced a 32.3% increase in the height of 40-day-old poplar plants and a 258% increase in the amount of adventitious root of 3-week-old subcultured plant clones. Overexpressed PdPapARF1 exerted its beneficial functions through modulating the hormone levels of indole acetic acid (IAA), jasmonic acid (JA), and salicylic acid (SA) in plants and activating their signaling pathways, creating similar results as inoculated with T. asperellum. Particularly, in the overexpressing poplar plants, the IAA level increased by approximately twice of the wild-type plants; and the signaling pathways of IAA, JA, and SA were drastically activated than the wild-type plants under pathogen attacks. Our report presents the potential of ARFs as the crucial and positive responders in plants to Trichoderma inducing.

Comparative Transcriptomics Suggests Early Modifications by Vintec® in Grapevine Trunk of Hormonal Signaling and Secondary Metabolism Biosynthesis in Response to Phaeomoniella chlamydospora and Phaeoacremonium minimum

“…Since then, the way in which Trichoderma spp. affect plant species in response to diverse abiotic and biotic stimuli has been widely studied ( Tucci et al, 2011 ; De Palma et al, 2019 ; Wang et al, 2020 ; Yan et al, 2021 ). For instance, several studies report that Trichoderma spp.…”

“…The role of auxin signaling has been widely studied in connection with growth promotion induced by Trichoderma. Initially, Trichoderma was thought to modulate plant growth via the production of hormone-like compounds ( Gravel et al, 2007 ; Contreras-Cornejo et al, 2009 ; Wang et al, 2020 ). Recent studies reveal that Trichoderma may activate the internal molecular mechanisms of plants, thereby altering hormonal signaling ( Martínez-Medina et al, 2017 ; Patel et al, 2019 ; Wang et al, 2020 ).…”

“…Initially, Trichoderma was thought to modulate plant growth via the production of hormone-like compounds ( Gravel et al, 2007 ; Contreras-Cornejo et al, 2009 ; Wang et al, 2020 ). Recent studies reveal that Trichoderma may activate the internal molecular mechanisms of plants, thereby altering hormonal signaling ( Martínez-Medina et al, 2017 ; Patel et al, 2019 ; Wang et al, 2020 ). Wang et al (2020) report that, in AUXR1, overexpressing poplar plantlets in which auxin is constitutively overproduced the level of indole-3-acetic acid decreases upon inoculation by T. asperellum .…”

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“…In this study, the mul-miRn73 was predicted to target the auxin regulator auxin response factor 1, which was proposed to be served as a transcription factor of auxin-responsive genes ( Wang W.Q. et al, 2020 ; Wang Y.F. et al, 2020 ).…”

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“…PdPapARF1-overexpressing plants showed a positive regulator for promoting poplar growth and defense responses, as does Trichoderma asperellum inoculation [54],…”