De novo transcriptomic profiling of the clonal Leymus chinensis response to long-term overgrazing-induced memory

Abstract

Sheepgrass (Leymus chinensis) is one of the dominant grass species present on typical steppes of the Inner Mongolia Plateau. However, L. chinensis has developed a dwarfing phenotype in response to the stressful habitat in grasslands that are severely degraded due to heavy grazing. The lack of transcriptomic and genomic information has prohibited the understanding of the transgenerational effect on physiological alterations in clonal L. chinensis at the molecular level in response to livestock grazing. To solve this problem, transcriptomic information from the leaves of clonal L. chinensis obtained from overgrazed (GR) and non-grazed (NG) grasslands was studied using a paired-end Illumina HiSeq 2500 sequencing platform. First, despite the influence of grazing being absent during the growth of clonal offspring in our hydroponic experiment, compared with those from the NG group, clonal L. chinensis from the GR group exhibited significant dwarf-type morphological traits. A total of 116,356 unigenes were subsequently generated and assembled de novo, of which 55,541 could be annotated to homologous matches in the NCBI non-redundant (Nr), Swiss-Prot, Clusters of Orthologous Groups (COG), gene ontology (GO), or Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. The expression of 3,341 unigenes significantly differed between the GR group and the NG group with an absolute value of Log2 ratio ≥ 1. The altered expression of genes involved in defence and immune responses, pathogenic resistance and cell development indicates that livestock grazing induces a transgenerational effect on the growth inhibition of clonal L. chinensis. The results of the present study will provide important large-scale transcriptomic information on L. chinensis. Furthermore, the results facilitated our investigation of grazing-induced transgenerational effects on both the morphological and physiological characteristics of L. chinensis at the molecular levels.

Untargeted Metabolome Analyses Revealed Potential Metabolic Mechanisms of Leymus chinensis in Response to Simulated Animal Feeding

“…With rapid progress in the omics’ era, new methods are available for the study of plant–herbivore interaction [ 22 ]. Transcriptomic analysis of cloned L. chinensis showed that grazing had a transgenerational effect on its growth inhibition and led to the development of a dwarf phenotype in response to the severe degradation of the grassland habitat due to heavy grazing [ 23 ]. In addition, transcriptomic analysis of overgrazed L. chinensis showed that most differentially expressed genes (DEGs) were significantly enriched in phenylpropanoid biosynthesis and flavonoid biosynthesis pathways [ 24 ].…”

Growth-Defense Trade-Offs Induced by Long-term Overgrazing Could Act as a Stress Memory

“…Dwarf forms of long-term grazed L. chinensis may be an adaptation to long-term grazing by large herbivores (Li et al, 2015 ). At the transcriptome and proteome level, the expression of the genes involved in defense and immune responses, pathogenic resistance, and cell development was changed, which collectively inhibited the growth of clonal L. chinensis (Ren et al, 2018a ). Furthermore, the proteins associated with dwarfism induced by OG were also altered, including upregulated ATPB_DIOEL and downregulated DNAK_GRATL, as well as proteins that interact with them, such as RPOB2_LEPTE, A0A023H9M8_9STRA, and RBL_AMOTI, (Ren et al, 2018b ).…”

Multi-omics analysis reveals the molecular changes accompanying heavy-grazing-induced dwarfing of Stipa grandis

“…The size of individual S. grandis plants is minimized to cope with frequent grazing or overgrazing (Wan et al, 2015;Li et al, 2018). The leaf photosynthetic activity, as indicated by net photosynthetic rate, stomatal conductance, intercellular carbon dioxide concentration, and transpiration rate, is markedly decreased following overgrazing (Ren et al, 2017). In recent years, several studies have been conducted to explore the molecular mechanism of plant dwarfism resulting from overgrazing at the transcription and protein levels (Wan et al, 2015;Ren et al, 2018a,b).…”