Transcriptome profilings of two tall fescue (Festuca arundinacea) cultivars in response to lead (Pb) stress.

Lead (Pb) is one of the most toxic heavy metal environmental pollutants. Tall fescue is an important cold season turf grass which can tolerate and accumulate substantial amount of Pb. To estimate genes related to Pb response and the molecular mechanism associated with Pb tolerance and accumulation, we analyzed the transcriptome of tall fescue in response to Pb treatment.

RNA-sequencing was performed in two tall fescue cultivars, Pb tolerant Silverado and Pb sensitive AST7001. A total of 810,146 assembled unique transcripts representing 25,415 unigenes were obtained from the tall fescue leaves. Among the panel, 3,696 differentially expressed genes (DEGs) were detected between the Pb treated (1000 mg/L) and untreated samples. Gene ontology (GO) and pathway enrichment analysis demonstrated that the DEGs were mainly implicated in energy metabolism, metabolism of terpenoids and polyketides, and carbohydrate metabolism related pathways. The expression patterns of 16 randomly selected genes were in consistent with that from the Solexa analysis using quantitative reverse-transcription PCR. In addition, compared to the common transcriptional response to Pb stress in both cultivars, the regulation of numerous genes including those involved in zeatin biosynthesis, limonene and pinene degradation, phagosome was exclusive to one cultivar.

The tall fescue assembled transcriptome provided substantial molecular resources for further genomics analysis of turfgrass in response to heavy metal stress. The significant expression difference of specific unigenes may account for Pb tolerance or accumulation in two different tall fescue cultivars. This study provided new insights for the investigation of the molecular basis of Pb tolerance and accumulation in tall fescue as well as other related turf grass species.