Comparative transcriptome analysis of the lichen-forming fungus Endocarpon pusillum elucidates its drought adaptation mechanisms

Abstract

The lichen-forming fungus was isolated from the desert lichen Endocarpon pusillum that is extremely drought resistant. To understand the molecular mechanisms of drought resistance in the fungus, we employed RNA-seq and quantitative real-time PCR to compare and characterize the differentially expressed genes in pure culture at two different water levels and with that in desiccated lichen. The comparative transcriptome analysis indicated that a total of 1781 genes were differentially expressed between samples cultured under normal and PEG-induced drought stress conditions. Similar to those in drought resistance plants and non-lichenized fungi, the common drought-resistant mechanisms were differentially expressed in E. pusillum. However, the expression change of genes involved in osmotic regulation in E. pusillum is different, which might be the evidence for the feature of drought adaptation. Interestingly, different from other organisms, some genes involved in drought adaption mechanisms showed significantly different expression patterns between the presence and absence of drought stress in E. pusillum. The expression of 23 candidate stress responsive genes was further confirmed by quantitative real-time PCR using dehydrated E. pusillum lichen thalli. This study provides a valuable resource for future research on lichen-forming fungi and shall facilitate future functional studies of the specific genes related to drought resistance. lichen, mycobiont, dehydration, drought adaption, drought resistant Citation:Wang YY, Zhang XY, Zhou QM, Zhang XL, Wei JC. Comparative transcriptome analysis of the lichen-forming fungus Endocarpon pusillum elucidates its drought adaptation mechanisms.

Functional analysis of thioredoxin from the desert lichen-forming fungus, Endocarpon pusillum Hedwig, reveals its role in stress tolerance

“…In our previous work on the comparative transcriptome analysis of E. pusillum , the expression of Eptrx was found up-regulated by 20% PEG18. In the current study, we further explored the underlying mechanism.…”

“…The comparative transcriptome analysis of our previous work indicated the expression of Eptrx was up-regulated with the treatment of 20% PEG for 21 days18. In this study, we further analyzed the transcript levels of Eptrx under PEG-induced drought stress condition by quantitative RT-PCR (Fig.…”

“…Accordingly, the adverse environmental stress on the lichen thallus can be simulated and studied by stress on the mycobiont. Indeed, the isolated mycobiont E. pusillum has been used in researching lichen stress resistance physiology and molecular mechanisms1618.…”

“…In our recent comparative transcriptome analysis of the lichen-forming fungus E. pusillum, a number of genes encoding proteins related to the antioxidant system were up-regulated under 20% PEG-induced dehydration stress. The genes include those that encode antioxidant enzymes and low-molecular-weight antioxidants such as glutathione and thioredoxin18.…”

Two new species of Endocarpon (Verrucariaceae, Ascomycota) from China

“…As dominant species, Endocarpon pusillum Hedw. has been intensively studied from many aspects, such as physiology under desiccation and starvation stress 10 , photosynthetic rate 11 , genome 12 , transcriptome 13 and stress resistance functional protein 14 . And all the above results supported that Endocarpon pusillum has good drought resistant ability, which could be one potential species used in the prospective ‘desert biocarpet engieering’ (DBCE) 15 , which has been proposed by Wei 16 , referring to developing during a short period into a dominant protection system instead of the naked desert with the help of the artificial inoculation of the microorganisms.…”