Arbuscular mycorrhizal (AM) fungi are soil-borne fungi belonging to the ancient phylum Glomeromycota and are important symbionts of the arbuscular mycorrhiza, enhancing plant nutrient acquisition and resistance to various abiotic stresses. In contrast to their significant physiological implications, the molecular basis involved is poorly understood, largely due to their obligate biotrophism and complicated genetics. Here, we identify and characterize three genes termed Fm201, Ri14-3-3 and RiBMH2 that encode 14-3-3-like proteins in the AM fungi Funneliformis mosseae and Rhizophagus irregularis, respectively. The transcriptional levels of Fm201, Ri14-3-3 and RiBMH2 are strongly induced in the pre-symbiotic and symbiotic phases, including germinating spores, intraradical hyphae- and arbuscules-enriched roots. To functionally characterize the Fm201, Ri14-3-3 and RiBMH2 genes, we took advantage of a yeast heterologous system owing to the lack of AM fungal transformation systems. Our data suggest that all three genes can restore the lethal Saccharomyces cerevisiae bmh1 bmh2 double mutant on galactose-containing media. Importantly, yeast one-hybrid analysis suggests that the transcription factor RiMsn2 is able to recognize the STRE (CCCCT/AGGGG) element present in the promoter region of Fm201 gene. More importantly, Host-Induced Gene Silencing of both Ri14-3-3 and RiBMH2 in Rhizophagus irregularis impairs the arbuscule formation in AM symbiosis and inhibits the expression of symbiotic PT4 and MST2 genes from plant and fungal partners, respectively. We further subjected the AM fungus-Medicago truncatula association system to drought or salinity stress. Accordingly, the expression profiles in both mycorrhizal roots and extraradical hyphae reveal that these three 14-3-3-like genes are involved in response to drought or salinity stress. Collectively, our results provide new insights into molecular functions of the AM fungal 14-3-3 proteins in abiotic stress responses and arbuscule formation during AM symbiosis.

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Purpose: The purpose of this study was to assess the effect of microbial biofertilizer and nanofertilizer on the growth, allicin content and elemental content of garlic in China. Method: We conducted field trial of microbial biofertilizer and germanium-containing controlled release nanofertilizer along two consecutive winter periods of 2020/2021 and 2021/2022 in a major garlic production area at Pizhou city to determine the effect of treatment in comparison to the local fertilization practice. Result: The results revealed that the application of microbial biofertilizer and germanium-containing controlled release nanofertilizer increased the bulb yield by approximately 6-28% and 14%, respectively, compared with local fertilization practice. Meanwhile, the application of microbial biofertilizer consistently increased the allicin content of garlic in year 2021 and 2022. Furthermore, we also observed a strong positive correlation between shoot nitrate concentration at spring garlic stage and the final garlic bulb yield, implying that the accumulation of nitrate content in garlic at spring garlic stage maybe beneficial to biomass accumulation through either nutritional effect and increased chilling tolerance. Conclusion: Taken together, our results revealed that the application of microbial biofertilizer and germanium-containing controlled release nanofertilizer can increase growth and nitrogen use efficiency of garlic in our experiment.