Growth-promoting bioactivities of Bipolaris sp. CSL-1 isolated from Cannabis sativa suggest a distinctive role in modifying host plant phenotypic plasticity and functions

Endophytic fungi have been considered as strong plant growth promoters due to phytohormones production. The current study reports the isolation of endophytic fungi from bio-prospective medicinal plant cannabis sativa. Endophytic fungus Bipolaris sp. CSL-1 from the leaves of C. sativa was isolated. Culture filtrate (CF) was primarily investigated for indole-3-acetic acid (IAA) and gibberellins (GAs) and was further evaluated for its capability to enhance mutant Waito-C rice growth attributes. A variety of plant growth characteristics, including seedling length, seedling biomass, and chlorophyll content, were significantly promoted by the CF, and the growth-promoting effect was due to IAA and various GAs in the CF. Gas chromatography/mass spectrometry analysis revealed the quantities (ng/mL) of various GAs, including GA1 (0.758 ± 0.005), GA3 (0.00015 ± 0.005), GA4 (0.945 ± 0.081), GA7 (0.6382 ± 0.012), GA9 (0.0125 ± 0.0002), and GA24 (0.0139 ± 0.0013). Similarly, endogenous GA4 (33.243 ± 4.36), GA24 (29.64 ± 2.68), GA7 (22.5 ± 1.3), and GA12 (25.21 ± 2.8) were significantly upregulated in rice mutant after CF application. Furthermore, RT-PCR indicated that IAA and GA pathway genes (des, ggs2, P50-1, P450-4, and iaaH) were expressed in CSL-1 and the combined application of CSL-1 spore suspension with yucasin and uniconazole to maize seedlings revealed that CSL-1 such as exogenous GA3 and IAA alleviated the negative effect of uniconazole and yucasin and promoted maize-seedling growth. These findings suggest that the endophytic fungus CSL-1, which produces IAA and GAs, can play a vital role in promoting plant growth and that CSL-1 could be used to enhance crop growth and mitigate plant stress under a variety of environmental conditions.