Comprehensive analysis of transcriptome response to salinity stress in the halophytic turf grass Sporobolus virginicus

Abstract

The turf grass Sporobolus virginicus is halophyte and has high salinity tolerance. To investigate the molecular basis of its remarkable tolerance, we performed Illumina high-throughput RNA sequencing on roots and shoots of a S. virginicus genotype under normal and saline conditions. The 130 million short reads were assembled into 444,242 unigenes. A comparative analysis of the transcriptome with rice and Arabidopsis transcriptome revealed six turf grass-specific unigenes encoding transcription factors. Interestingly, all of them showed root specific expression and five of them encode bZIP type transcription factors. Another remarkable transcriptional feature of S. virginicus was activation of specific pathways under salinity stress. Pathway enrichment analysis suggested transcriptional activation of amino acid, pyruvate, and phospholipid metabolism. Up-regulation of several unigenes, previously shown to respond to salt stress in other halophytes was also observed. Gene Ontology enrichment analysis revealed that unigenes assigned as proteins in response to water stress, such as dehydrin and aquaporin, and transporters such as cation, amino acid, and citrate transporters, and H+-ATPase, were up-regulated in both shoots and roots under salinity. A correspondence analysis of the enriched pathways in turf grass cells, but not in rice cells, revealed two groups of unigenes similarly up-regulated in the turf grass in response to salt stress; one of the groups, showing excessive up-regulation under salinity, included unigenes homologos to salinity responsive genes in other halophytes. Thus, the present study identified candidate genes involved in salt tolerance of S. virginicus. This genetic resource should be valuable for understanding the mechanisms underlying high salt tolerance in S. virginicus. This information can also provide insight into salt tolerance in other halophytes.

Endophytes from wild cereals protect wheat plants from drought by alteration of physiological responses of the plants to water stress

“…The 2-oxocarboxilic acid pathway is associated with the biosynthesis of amino acids, mainly asparagine and glutamate, that are involved in resistance to abiotic stress through the production of 2-oxoacids (O'Leary et al, 2011). Glutamate is directly associated with abiotic plant responses because it is used as a precursor for production of compatible osmolytes including proline and polyamine (Roberts, 2005;Yamamoto et al, 2015). Additionally, amino acids such as tryptophan and phenylalanine accumulate in maize and wheat under drought stress (Bowne et al, 2012;Witt et al, 2012).…”

Mechanisms of Environmental Stress Tolerance in Turfgrass

“…Investigating the salt stress response at the molecular level is a possible way to further understand salt tolerance mechanism of bermudagrass. Transcriptome profilings of Kentucky bluegrass, zoysiagrass, and salt couch grass (Sporobolus virginicus) have been analyzed comprehensively, and a number of candidate unigenes related to salt stress responses were identified [49][50][51]; putatively, a total of 36,587, 1455 and 8340 differentially expressed genes were detected for these species, respectively. Functional annotation indicated that the detected genes were related to transcription factors, processes and pathways such as oxidation-reduction process, ion transport and ROS scavenging.…”

Transcriptome analysis of salt-responsive genes and SSR marker exploration in Carex rigescens using RNA-seq

“…(Xie et al 2015) and the highly polyploidy, facultative apomictic Kentucky bluegrass (Poa pratensis L.) (Bushman et al 2016) using transcriptome technology. Furthermore, using these RNA-seq databases, candidate genes involved in salt tolerance have been identified in the halophytic turfgrass Sporobolus virginicus (Yamamoto et al 2015) and in both shoot and root tissues of Kentucky bluegrass (Bushman et al 2016). The protective roles of exogenous melatonin in response to salt stress have been illustrated in the widely planted turfgrass bermudagrass (Cynodon dactylon) (Shi et al 2015).…”