Abstract The ongoing diversification of plant defence compounds exerts dynamic selection pressures on the microorganisms that colonize plant tissues. Evolutionary processes that generate resistance towards these compounds increase microbial fitness by giving access to plant resources and increasing pathogen virulence. These processes entail sequence‐based mechanisms that result in adaptive gene functions, and combinatorial mechanisms that result in novel syntheses of existing gene functions. However, the priority and interactions among these processes in adaptive resistance remain poorly understood. Using a combination of molecular genetic and computational approaches, we investigated the contributions of sequence‐based and combinatorial processes to the evolution of fungal metabolic gene clusters encoding stilbene cleavage oxygenases (SCOs), which catalyse the degradation of biphenolic plant defence compounds known as stilbenes into monophenolic molecules. We present phylogenetic evidence of convergent assembly among three distinct types of SCO gene clusters containing alternate combinations of phenolic catabolism. Multiple evolutionary transitions between different cluster types suggest recurrent selection for distinct gene assemblages. By comparison, we found that the substrate specificities of heterologously expressed SCO enzymes encoded in different clusters types were all limited to stilbenes and related molecules with a 4′‐OH group, and differed modestly in substrate range and activity under the experimental conditions. Together, this work suggests a primary role for genome structural rearrangement, and the importance of enzyme modularity, in promoting fungal metabolic adaptation to plant defence chemistry.
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Chromatic Acclimation in Cyanobacteria: A Diverse and Widespread Process for Optimizing Photosynthesis
Chromatic acclimation (CA) encompasses a diverse set of molecular processes that involve the ability of cyanobacterial cells to sense ambient light colors and use this information to optimize photosynthetic light harvesting. The six known types of CA, which we propose naming CA1 through CA6, use a range of molecular mechanisms that likely evolved independently in distantly related lineages of the Cyanobacteria phylum. Together, these processes sense and respond to the majority of the photosynthetically relevant solar spectrum, suggesting that CA provides fitness advantages across a broad range of light color niches. The recent discoveries of several new CA types suggest that additional CA systems involving additional light colors and molecular mechanisms will be revealed in coming years. Here we provide a comprehensive overview of the currently known types of CA and summarize the molecular details that underpin CA regulation.
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- Award ID(s):
- 1818187
- PAR ID:
- 10207649
- Date Published:
- Journal Name:
- Annual Review of Microbiology
- Volume:
- 73
- Issue:
- 1
- ISSN:
- 0066-4227
- Page Range / eLocation ID:
- 407 to 433
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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