A Seed Mucilage-Degrading Fungus From the Rhizosphere Strengthens the Plant-Soil-Microbe Continuum and Potentially Regulates Root Nutrients of a Cold Desert Shrub

Abstract

Seed mucilage plays important roles in the adaptation of desert plants to the stressful environment. Artemisia sphaerocephala is an important pioneer plant in the Central Asian cold desert, and it produces a large quantity of seed mucilage. Seed mucilage of A. sphaerocephala can be degraded by soil microbes, but it is unknown which microorganism(s) can degrade mucilage or how the mucilage-degrading microorganisms affect rhizosphere microbial communities or root nutrients. Here, mucilage-degrading microorganisms were isolated from the rhizosphere of A. sphaerocephala, screened by incubation with mucilage stained with congo red and identified by sequencing and phylogenetic analyses. Fungal-bacterial networks based on high-throughput sequencing of rhizosphere microbes were constructed to explore the seasonal dynamic of interactions between mucilage-degrading microorganism(s) and its closely related microorganisms. The structural equation model was used to analyze effects of the mucilage-degrading microorganism, rhizosphere fungal/bacterial communities and soil physicochemical properties on root C and N. A mucilage-degrading microorganism was identified as the fungus Phanerochaete chrysosporium. Relative abundance of the mucilage-degrading fungus (MDF) was highest in May. Sub-networks showed that the abundance of fungi and bacteria closely related to the MDF also were highest in May. Interactions between the MDF and related fungi and bacteria were positive, which might enhance mucilage degradation. In addition, the MDF might regulate root C and N by affecting rhizosphere microbial community structure. Our results suggest that the MDF from the rhizosphere strengthens the plant-soil-microbe continuum, thereby potentially regulating microbial interactions and root nutrients of A. sphaerocephala.

Biotic stress-induced changes in root exudation confer plant stress tolerance by altering rhizospheric microbial community

“…Artemisia sphaerocephala, a remarkable plant of Asian cold deserts, was used in a study where mucilage-degrading microbes were isolated from the root-soil junction. From the study, it becomes evident that the MDF associated with the roots of A. sphaerocephala recruit bacterial groups like Actinobacteria, Firmicutes, Proteobacteria, and Verrucomicrobia towards the roots and regulate the rhizosphere microbiota (Hu et al, 2021). Further, microfluidics-based investigation for real-time study of plant-microbe interaction revealed that Bacillus subtilis exhibits chemotactic behaviour towards the root elongation zone, which might be due to the secretion of root exudates (Massalha et al, 2017;Sasse et al, 2018).…”