What distinguishes cyanobacteria able to revive after desiccation from those that cannot: the genome aspect

Abstract

Filamentous cyanobacteria are the main founders and primary producers in biological desert soil crusts (BSCs) and are likely equipped to cope with one of the harshest environmental conditions on earth including daily hydration/dehydration cycles, high irradiance and extreme temperatures. Here, we resolved and report on the genome sequence of Leptolyngbya ohadii, an important constituent of the BSC. Comparative genomics identified a set of genes present in desiccation-tolerant but not in dehydration-sensitive cyanobacteria. RT qPCR analyses showed that the transcript abundance of many of them is upregulated during desiccation in L. ohadii. In addition, we identified genes where the orthologs detected in desiccation-tolerant cyanobacteria differs substantially from that found in desiccation-sensitive cells. We present two examples, treS and fbpA (encoding trehalose synthase and fructose 1,6-bisphosphate aldolase respectively) where, in addition to the orthologs present in the desiccation-sensitive strains, the resistant cyanobacteria also possess genes with different predicted structures. We show that in both cases the two orthologs are transcribed during controlled dehydration of L. ohadii and discuss the genetic basis for the acclimation of cyanobacteria to the desiccation conditions in desert BSC.

Genomic and transcriptomic insights into the survival of the subaerial cyanobacterium Nostoc flagelliforme in arid and exposed habitats

“…Murik et al . () recently identified 31 genes that are specific for desiccation‐tolerant cyanobacteria. The here presented genome sequence of N. flagelliforme CCNUN1 is the first example for a subaerial cyanobacterium.…”

“…Using a blastP e ‐value cut‐off of 10 −80 , we found only 10 orthologs of the 31 genes (Supporting Information Table S10), and four of these orthologs, involved in the chemotaxis response, correspond to a single gene as defined by Murik et al . (). The fewer number of orthologs found in this study in part may result from the distant phylogenetic relationship among Nostoc , Leptolyngbya and Microcoleus (Supporting Information Fig.…”

“…Understanding the environmental adaptation mechanisms of desiccation-tolerant cyanobacteria has great significance for reversing desertification and implications for genetic improvement of drought tolerance in crop plants. Murik et al (2017) recently identified 31 genes that are specific for desiccation-tolerant cyanobacteria. The here presented genome sequence of N. flagelliforme CCNUN1 is the first example for a subaerial cyanobacterium.…”

“…The here presented genome sequence of N. flagelliforme CCNUN1 is the first example for a subaerial cyanobacterium. Using a blastP e-value cut-off of 10 −80 , we found only 10 orthologs of the 31 genes (Supporting Information Table S10), and four of these orthologs, involved in the chemotaxis response, correspond to a single gene as defined by Murik et al (2017). The fewer number of Supporting Information Table S12.…”

“…Desiccation‐tolerant filamentous cyanobacteria have been associated with important roles in the formation of biological desert soil crusts (BSCs), where they are regarded as pioneering species and main primary producers. These cyanobacteria face extreme environments, including large temperature fluctuations and daily hydration/dehydration cycles (Murik et al, ). Desiccation‐tolerant cyanobacteria were suggested to have evolved a broad range of survival strategies to cope with these extreme conditions, including the accumulation of intracellular osmotic substances (Lebre et al, ), enhanced exopolysaccharide production and accumulation of secreted proteins in an immobilized matrix (Tamaru et al, ), and re‐modulation of energy transfer pathways by changing the states of light‐harvesting protein complexes (Bar Eyal et al, ).…”