Global Transcriptome Profiles of 'Meyer' Zoysiagrass in Response to Cold Stress

Abstract

A long green period is essential for a turfgrass species with high ornamental value and a wide area of use. Zoysiagrasses (Zoysia spp. Willd.) are perennial turfgrass species popular in tropical, subtropical and temperate zones, possessing many properties necessary to be economically useful turfgrass. They do not have a long green period because of cold sensitivity. A main focus in zoysiagrass research is to develop cold tolerant cultivars. Understanding the cold response in zoysiagrass is a fundamental area of research. In the present study, ‘Meyer’ zoysiagrass (Zoysia japonica), a widely cultivated variety in the genus, is used. We employed RNA-Seq to investigate genome-wide gene expression profiles in leaves under cold stress (4°C). Using the Illumina sequencing platform, we obtained approximately 206 million high-quality paired-end reads from three libraries (0 h, 2 h, and 72 h cold treatment at 4°C). After de novo assembly and quantitative assessment, 46,412 unigenes were generated with an average length of 998 bp and an N50 of 1,522 bp. A total of 25,644 (55.2%) unigenes were annotated by alignment with public protein databases including NR, SwissProt, KEGG and KOG. Differentially expressed genes (DEGs) were investigated using the RPKM method. A total of 756 DEGs were identified between 0h and 2h-cold treatment, with 522 up-regulated and 234 down-regulated; and 5327 DEGs were identified between 0h and 72h-cold treatment, with 2453 up-regulated and 2874 down-regulated. The expression profile of 15 DEGs selected randomly was confirmed with qRT-PCR. The results suggest that cold stress can induce desiccation and oxidative stress, inhibit photosynthesis and substance transport. In response to the stress, genes involved in proline synthesis, in starch hydrolysis, in methionine and ascorbic acid metabolism, in SOD activity, and in DREBs response pathway were up-regulated. GA metabolism, ABA and JA stimulus response were affected under cold exposure. This is the first transcriptome sequencing of Z. japonica, providing a large set of sequence data as well as gene expression profiles under cold stress. It will improve our current understanding of the cold response of zoysiagrass and be beneficial in breeding research.

Changes in Lolium perenne transcriptome during cold acclimation in two genotypes adapted to different climatic conditions

“…This is not surprising because both genotypes have shown acquisition of freezing tolerance during cold acclimation [ 15 ]. Consistent with the previous studies [ 2 , 4 , 37 ] our results also showed the induction genes involved in protective mechanisms such as redox homeostasis mechanisms, signal transduction, cell membrane stabilization, and carbohydrate metabolism during cold acclimation. Induction of cold-responsive genes such as cold-regulated , dehydration-responsive , late-embryogenesis-abundant , and ice recrystallization inhibition homolog genes has been shown previously in perennial ryegrass cv.…”

Mechanisms of Environmental Stress Tolerance in Turfgrass

“…Cold-response-related genes such as late embryogenesis abundant proteins (LEA), C-repeat-binding factor/DRE-binding factor (CBF1), SOD, and POD were up-regulated by cold stress [152]. The transcriptomic analyses of bermudagrass and zoysiagrass under cold stress revealed that many genes related to photosynthesis, carbon fixation, nitrogen metabolism, and proline synthesis pathways were involved in the regulation of cold response [158,159]. Recently, several differentially expressed proteins related to cold response, including lipid stability, antioxidant enzymes, protein synthesis, and degradation, were identified in bermudagrass [160].…”

Functional and RNA-Sequencing Analysis Revealed Expression of a Novel Stay-Green Gene from Zoysia japonica (ZjSGR) Caused Chlorophyll Degradation and Accelerated Senescence in Arabidopsis

“…It has been a desire of the turfgrass breeders for a long time to cultivate zoysiagrass cultivars with longer green period and better visual appearance. Nevertheless, limited genetic resources are available for zoysiagrass to date (Wei et al, 2015; Tanaka et al, 2016), and the senescence mechanism are far from being well-illustrated. The objectives of this study were: (i) to identify a stay-green protein gene in Z. japonica ; (ii) to investigate its characters and explore its functional roles; and (iii) to further explore its regulatory network in senescence.…”