Search

Summary: Endoplasmic reticulum (ER) bodies are ER‐derived structures that contain a large amount of PYK10 myrosinase, which hydrolyzes tryptophan (Trp)‐derived indole glucosinolates (IGs). Given the well‐described role of IGs in root–microbe interactions, we hypothesized that ER bodies in roots are important for interaction with soil‐borne microbes at the root–soil interface.We used mutants impaired in ER bodies (nai1), ER body‐resident myrosinases (pyk10bglu21), IG biosynthesis (myb34/51/122), and Trp specialized metabolism (cyp79b2b3) to profile their root microbiota community in natural soil, evaluate the impact of axenically collected root exudates on soil or synthetic microbial communities, and test their response to fungal endophytes in a mono‐association setup.Tested mutants exhibited altered bacterial and fungal communities in rhizoplane and endosphere, respectively. Natural soils and bacterial synthetic communities treated with mutant root exudates exhibited distinctive microbial profiles from those treated with wild‐type (WT) exudates. Most tested endophytes severely restricted the growth of cyp79b2b3, a part of which also impaired the growth of pyk10bglu21.Our results suggest that root ER bodies and their resident myrosinases modulate the profile of root‐secreted metabolites and thereby influence root–microbiota interactions. [ABSTRACT FROM AUTHOR]

Glucosinolates are specialized defensive metabolites characteristic of the Brassicales order. Among them, aliphatic and indolic glucosinolates (IGs) are usually highly abundant in species from the Brassicaceae family. The exceptions this trend are species representing a subclade of the Camelineae tribe, including Capsella and Camelina genera, which have reduced capacity to produce and metabolize IGs. Our study addresses the contribution of specific glucosinolate-related myeloblastosis (MYB) transcription factors to this unprecedented backward evolution of IG biosynthesis. To this end, we performed phylogenomic and functional studies of respective MYB proteins. The obtained results revealed weakened conservation of glucosinolate-related MYB transcription factors, including loss of functional MYB34 protein, in the investigated species. We showed that the introduction of functional MYB34 from Arabidopsis thaliana partially restores IG biosynthesis in Capsella rubella , indicating that the loss of this transcription factor contributes to the backward evolution of this metabolic pathway. Finally, we performed an analysis of the impact of particular myb mutations on the feedback loop in IG biosynthesis, which drives auxin overproduction, metabolic dysregulation and strong growth retardation caused by mutations in IG biosynthetic genes. This uncovered the unique function of MYB34 among IG-related MYBs in this feedback regulation and consequently in IG conservation in Brassicaceae plants. [ABSTRACT FROM AUTHOR]