MARIK, D. | bioRxiv Science

bioRxiv2024

Effects of nano urea on growth and gene expression of Arabidopsis thaliana in hydroponics

IntroductionHydroponics enables precise control over nutrient delivery, optimized water requirements and growing conditions. The combination of nanotechnology and hydroponics paves the way towards sustainable agriculture with less environmental footprints. We investigated the effects of nano urea on the model plant Arabidopsis thaliana in hydroponics. MethodsA growth experiment in a nitrogen-free hydroponic medium compared the effects of a liquid nano urea formulation (NUF) marketed by Indian Farmers Fertilizer Cooperative (IFFCO) to an equimolar bulk urea. Transcriptome analysis identified the molecular mechanisms of growth enhancement. Dynamic light scattering and transmission electron microscopy confirmed NUFs negative surface charge and sub-100 nm size, correlating its uptake and distribution in the plant. Results and discussionA two-week growth in the hydroponic medium with 70 M NUF led to a 20% higher biomass and 16% higher chlorophyll content than a medium with 70 M urea. Higher doses of NUF inhibited growth, whereas higher equivalent urea doses did not. NUF led to the differential expression of more genes than urea at 12 h to seven days of treatment. Nitrogen assimilation, growth, photosynthesis, and stress tolerance genes showed higher transcript levels in NUF than in urea. On the other hand, NUF led to greater suppression of many negative growth-regulating genes. After seven days of treatment, chlorophyll biosynthesis genes got up-regulated, while chlorophyll catabolism genes got down-regulated at higher levels by NUF than by urea, correlating with the higher chlorophyll content of NUF-treated seedlings. In conclusion, NUF outperformed equimolar urea for the growth promotion of A. thaliana at a low concentration in hydroponics, leading to a greater regulation of genes for nitrogen metabolism and chlorophyll biosynthesis. Our results suggest a potential use of NUF as a nitrogen fertilizer for hydroponic agriculture.

plant biology↗

bioRxiv2023

Peribacillus frigoritolerans T7-IITJ, a potential biofertilizer, induces plant growth-promotinggenes of Arabidopsis thaliana

This study aimed to isolate plant growth and drought tolerance-promoting bacteria from the nutrient- poor rhizosphere soil of several plant species from the Thar desert and unravel their molecular mechanisms of plant growth promotion, to develop effective biofertilizers for arid agriculture. Among our isolates of Thar desert rhizobacteria, Enterobacter cloacae C1P-IITJ, Kalamiella piersonii J4-IITJ, and Peribacillus frigoritolerans T7-IITJ, significantly enhanced root and shoot growth in the model plant Arabidopsis thaliana under PEG-induced drought stress in the lab. Whole genome sequencing and biochemical analyses of the non-pathogenic bacterium T7-IITJ revealed its plant growth-promoting traits, viz., solubilization of phosphate, iron, and nitrate and production of exopolysaccharides and auxin. Transcriptome analysis of Arabidopsis thaliana inoculated with T7-IITJ and exposure to drought revealed the induction of plant genes for photosynthesis, auxin and jasmonate signaling, nutrient mining and sequestration, redox homeostasis, and secondary metabolite biosynthesis pathways related to beneficial bacteria-plant interaction, but repression of many stress-responsive genes. Biochemical analyses indicated enhanced proline, chlorophyll, iron, phosphorous, and nitrogen content and reduced reactive oxygen species in plant tissues due to T7-IITJ inoculation. This bacterium could also improve the germination and seedling growth of Tephrosia purpurea, Triticum aestivum, and Setaria italica under drought. Additionally, T7-IITJ inhibited the growth of two plant pathogenic fungi, Rhizoctonia solani, and Fusarium oxysporum. These results suggest P. frigoritolerans T7-IITJ is a potent biofertilizer which can regulate plant genes promoting growth and drought tolerance.

plant biology↗