Isolation of Salt Stress-Related Genes fromAspergillus glaucusCCHA by Random Overexpression inEscherichia coli
The halotolerant fungusAspergillus glaucusCCHA was isolated from the surface of wild vegetation around a saltern with the salinity range being 0–31%. Here, a full-length cDNA library ofA. glaucusunder salt stress was constructed to identify genes related to salt tolerance, and one hundred clones were randomly selected for sequencing and bioinformatics analysis. Among these, 82 putative sequences were functionally annotated as being involved in signal transduction, osmolyte synthesis and transport, or regulation of transcription. Subsequently, the cDNA library was transformed intoE. colicells to screen for putative salt stress-related clones. Five putative positive clones were obtained fromE. colicells grown on LB agar containing 1 M NaCl, on which they showed rapid growth compared to the empty vector control line. Analysis of transgenicArabidopsis thalianalines overexpressingCCHA-2142demonstrated that the gene conferred increased salt tolerance to plants as well by protecting the cellular membranes, suppressing the inhibition of chlorophyll biosynthesis. These results highlight the utility of thisA. glaucuscDNA library as a tool for isolating and characterizing genes related to salt tolerance. Furthermore, the identified genes can be used for the study of the underlying biology of halotolerance.