Azomite, a volcanic ash-based fertilizer modulates gene expression during photomorphogenesis through phyB-dependent and independent pathways

Authors: MEHLFERBER, ELIJAH - University Of California Berkeley; Mc Cue, Kent; YANG, BI - Carnegie Institute - Stanford; REED, ROBERT - I-Cultiver; FERREL, JON - Azomite Mineral Products, Inc; KHANNA, RAJNISH - I-Cultiver

Submitted to: Plant Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2025
Publication Date: 5/29/2025
Citation: Mehlferber, E., Mc Cue, K.F., Yang, B., Reed, R., Ferrel, J., Khanna, R. 2025. Azomite, a volcanic ash-based fertilizer modulates gene expression during photomorphogenesis through phyB-dependent and independent pathways. Plant Gene. 43. Article 100523. https://doi.org/10.1016/j.plgene.2025.100523.
DOI: https://doi.org/10.1016/j.plgene.2025.100523

Interpretive Summary: This study investigates the effects of a volcanic ash-based fertilizer, Azomite, on plant growth and nutrient uptake. After confirming preliminary experiments on tomato plants, gene expression changes in Arabidopsis seedlings were analyzed in response to azomite under different light conditions. Azomite contains over 70 minerals and trace elements and has been shown to enhance tomato fruit production, suggesting that it may influence plant metabolism. The research focuses on how Azomite regulates genes involved in carbon assimilation and nutrient uptake, specifically the SUBERMAN gene, which controls root suberization. Arabidopsis seedlings treated with Azomite under continuous red light displayed increased growth, while seedlings in darkness showed no significant changes, highlighting the role of Azomite in preparing seedlings to respond to light. Comparative studies using light sensing mutants revealed overlapping genes regulated by light and Azomite. The study also established dose-dependent responses to Azomite in both tomato plants and Arabidopsis seedlings, with higher doses reducing effectiveness. Previous findings suggest that Azomite may enhance nutrient uptake by modulating root exudates, which alter the root microbiome and promote carbohydrate metabolism. This research contributes to the understanding of how micronutrient-rich fertilizers like Azomite affect plant growth and their ability to respond to light, with potential implications for agricultural practices and crop production optimization.

Technical Abstract: Azomite is a lightly weathered dacitic (rhyolitic) tuff breccia (DTB), it is silicon-based with over 70 minerals and trace elements (micronutrients). In previous studies, the application of Azomite increased greenhouse tomato production. In the tomato root endosome, Azomite caused functional shifts from a higher abundance of microbes involved in metabolism of 2- to 4- carbon compounds to higher levels of microbes involved in carbohydrate metabolism. This suggested a possible increase in carbohydrate production and shift in exudates involved in microbial recruitment. Parallel studies with 4-day old Arabidopsis seedlings revealed that photosynthetically active radiation was required for Azomite-induced increase in both hypocotyl length and cotyledon area. These data suggested that Azomite may influence growth through changes in photosynthesis, leading to carbohydrate-enriched root exudates and increased growth. Here, we present RNAseq analysis in response to Azomite of 4-day old Arabidopsis seedlings grown either in continuous darkness (Dc) or under continuous red-light (Rc). Significant changes in genes involved in carbon assimilation and nutrient uptake, amongst other functional pathway categories are reported. Comparison with phyB (phytochrome B, red-light photoreceptor) mutant seedlings is shown to determine the overlap between phyB-regulated genes and Azomite-responsive genes. Two concentrations, 0.5 g and 1.0 g of Azomite were included because our previous results with tomato and Arabidopsis exhibited a dose-dependent response. Several genes are identified as responding differentially, including SUBERMAN, a myb-family transcription factor that regulates suberization of the root endodermis. This study advances our understanding of how complex mixtures of micronutrients such as Azomite influence gene expression during plant growth and development.