A simple method for in vitro growth stimulation of tomato plantlets (Solanum lycopersicum)…

Arbuscular mycorrhizal fungi (AMF) have primarily been utilized as hardening agents for micropropagated plants. While in vitro co-culture models between AMF and plants exist, they are limited to pre-rooted explants and require either placing spores near roots, coating seeds with spores, or promoting root growth through water. Thus, this study aimed to create a simpler in vitro plant-fungal co-culture model for promoting plant growth, which can be applied at the beginning of plant culture and ensure no fungus-disinfectant contact. The hypothesis was that tomato seeds on the modified MS medium would germinate and form symbiosis with Rhizophagus irregularis MUCL43194 spores in the medium without any supporting steps. The findings from our study confirmed the hypothesis by the AMF-induced growth enhancement of inoculated tomato plantlets (high leaf number, plant fresh weight, and root number). Moreover, qPCR quantification with genomic DNA from inoculated root systems and specific primers for the large subunit nuclear ribosomal DNA of the fungus (LSU nrDNA) demonstrated successful establishment of the in vitro mycorrhiza, with increased colonization from the first to the third week of culture. AMF hyphae were also detected in tomato roots stained with 0.01% carbol fuchsin. However, despite the promoted growth of tomato plantlets, there was no further increase in LSU nrDNA copy number after three weeks of culture, which may be due to the low light intensity used in the experiment. To optimize the AMF-plant in vitro co-culture model, future studies should investigate different light intensities to increase plant photosynthesis and prolong AMF growth.

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Citation: An Nguyen Hoang, Nguyen Phan Thi Thao, Nga Nguyen Thi Minh, Nhi Ho Thi Hoang, Loc Nguyen Duc Bao, Phuc Nguyen Le Hoang, Vu Do Hoang, Nam Nguyen Quang Phuong, Khanh Truong Thi Minh, Phuc Tran Thien, Chi Le Thi Kim, Phuong Truong Thi Bich (2023) A simple method for in vitro growth stimulation of tomato plantlets (Solanum lycopersicum) through supplementation of Rhizophagus irregularis MUCL43194 spores in the MS culture medium. Plant Cell Tiss Organ Cult. https://doi.org/10.1007/s11240-023-02493-8