Transcriptomic Analysis Reveals Genes Mediating Salt Tolerance through Calcineurin/CchA-Independent Signaling inAspergillus nidulans

Abstract

Adaptation to changes in the environment is crucial for the viability of all organisms. Although the importance of calcineurin in the stress response has been highlighted in filamentous fungi, little is known about the involvement of ion-responsive genes and pathways in conferring salt tolerance without calcium signaling. In this study, high-throughput RNA-seq was used to investigate salt stress-induced genes in the parent, ΔcnaB, and ΔcnaBΔcchA strains of Aspergillus nidulans, which differ greatly in salt adaption. In total, 2,884 differentially expressed genes including 1,382 up- and 1,502 downregulated genes were identified. Secondary transporters, which were upregulated to a greater extent in ΔcnaBΔcchA than in the parent or ΔcnaB strains, are likely to play important roles in response to salt stress. Furthermore, 36 genes were exclusively upregulated in the ΔcnaBΔcchA under salt stress. Functional analysis of differentially expressed genes revealed that genes involved in transport, heat shock protein binding, and cell division processes were exclusively activated in ΔcnaBΔcchA. Overall, our findings reveal that secondary transporters and stress-responsive genes may play crucial roles in salt tolerance to bypass the requirement for the CchA-calcineurin pathway, contributing to a deeper understanding of the mechanisms that influence fungal salt stress adaption in Aspergillus.

Growth study under combined effects of temperature, pH and salinity and transcriptome analysis revealed adaptations of Aspergillus terreus NTOU4989 to the extreme conditions at Kueishan Island Hydrothermal Vent Field, Taiwan

“…Based on phylogenetic analyses of the calmodulin gene, isolates of A. terreus cultured from marine/sea-related environments intermixed with those cultured from terrestrial habitats, suggesting that the marine isolates are not phylogenetically distinct [46,47]. The Aspergillus terreus isolate in this study may be of a terrestrial origin as the molecular mechanisms expressed towards salt tolerance (arginine biosynthesis, HOG, MAPK) are similar to those expressed by other terrestrial Aspergillus species, such as A. oryzae [43], A. nidulans [48], A. fumigatus [49] and A. montevidensis [50]. Aspergillus species have been shown to be able to tolerate a range of environmental stressors by their repertoire of stress-related genes [37,41,[49][50][51][52][53][54][55][56][57] and were found ubiquitous in deep-sea environments.…”

Comparative transcriptomics of sevenImpatiensspecies

“…This protein is part of protein complex, which physically connect endoplasmatic reticulum and mitochondria. Wang et al (130) showed upregulation of this gene in Aspergillus nidulans under salinity stress.…”

Aspergillus flavus NRRL 35739, a Poor Biocontrol Agent, May Have Increased Relative Expression of Stress Response Genes

“…Heat shock proteins are a ubiquitous family of proteins involved in responses to many abiotic stresses, including heat, salinity, and oxidative stresses [43,44,45,46,47]. They are named by their molecular weight in kildodaltons and often serve as molecular chaperones, helping nascent and denatured peptides fold properly or be tagged for degradation.…”