Project description:Tapping panel dryness (TPD) seriously affects the natural rubber (NR) production of Hevea brasiliensis (rubber tree). Several studies have speculated that TPD influences NR biosynthesis in the latex of rubber trees based on the expression changes of NR biosynthesis-related genes. In this study, iTRAQ analysis of latex were carried out to reveal the molecular mechanism of TPD affecting rubber trees NR biosynthesis activity and molecular weight.
Project description:This study is committed to de novo sequencing and comparative analysis of the transcriptomes of healthy (H) and Tapping panel dryness (TPD)-affected (T) rubber trees to identify the genes and pathways related to the TPD. Total raw reads of 34,632,012 and 35,913,020 bp were obtained from H and T library, respectively using Illumina Hiseq 2000 sequencing technology. De novo assemblies yielded 141,456 and 169,285 contigs, and 96,070 and 112,243 unigenes from H and T library, respectively. Among 66535 genes, 107021 genes were identified as differential expressed genes between H and T library via comparative transcript profiling. A majority of genes involved in natural rubber biosynthesis and jasmonate synthesis with most potential relevance in TPD occurrence were found to be differentially expressed. In TPD-affected trees, the expression of most genes related to the latex biosynthesis and jasmonate synthesis was severely inhibited and it probably the direct cause of the TPD. Our de novo transcriptome data sets provide a significant resource for the discovery of genes related to TPD and improve our understanding the occurrence and maintainace of TPD.
Project description:Nutural rubber (NR) production, latex is harvested by periodical tapping of the trunk bark. Ethylene enhances and prolongs latex flow and latex regeneration. Ethephon, which is an ethylene-releasing compound, applied to the trunk before tapping usually results in a 1.5- to 2-fold increase in latex yield. We investigated gene expression in response to ethephon treatment using Pará rubber tree seedlings as a model system. After ethephon treatment, 3,270 genes showed significant differences in expression compared with the mock treatment. Genes associated with carotenoids, flavonoids, and abscisic acid biosynthesis were significantly upregulated by ethephon treatment, which might contribute to an increase in latex flow. Genes associated with secondary cell wall formation were downregulated, which might be because of the reduced sugar supply. Given that sucrose is an important molecule for NR production, a trade-off may arise between NR production and cell wall formation for plant growth and for wound healing at the tapping panel.
Project description:Currently, one of the most serious threats in rubber tree is the tapping panel dryness (TPD) that greatly restricts the natural rubber production. Over tapping or ethephon stimulation is regarded as the main cause of TPD occurrence. Although extensive studies have been carried out, the molecular mechanism on the TPD still remains puzzled. In the present study, TMT proteome analysis of barks of rubber trees were performed to extend our understanding of the nature and molecular mechanism underlying TPD.
2023-10-08 | PXD045968 | iProX
Project description:Transcriptome sequencing of tapping panel dryness affected rubber trees
Project description:Purpose: de novo sequencing and comparative analysis of the bark transciptomes of Hevea brasiliensis induced without ethephon (C), with ethephon for 8 hours (E8) and 24 hours (E24) to identify the genes and pathways related to the stimulation of rubber production by ethylene. The goals of this study are to reveal the molecular mechanism behind the stimulation of rubber production by ethylene. Methods: Bark RNA was extracted using the TRIzol® Reagent (Invitrogen) and two cDNA libraries, H (healthy rubber trees) and T (TPD-affected trees), were prepared using the mRNA-Seq 8 sample prep Kit (Illumina). The libraries were deep sequenced using Illumina HiSeqTM 2000 (Illumina Inc., San Diego, CA, USA). Raw reads produced from sequencing machines were resorted to de novo assembly and gene annotation. Results: De novo sequencing and assembly of the bark transciptomes of Hevea brasiliensis induced with ethephon for 8 hours (E8) and 24 hours (E24) were performed. 51,965,770, 52,303,714 and 53,177,976 high-quality clean reads from E8, E24 and C (control) samples were assembled into 81,335, 80,048 and 80,800 unigenes respectively, with a total of 84,425 unigenes and an average length of 1,101 bp generated. 10,216 and 9,374 differentially expressed genes (DEGs) in E8 and E24 compared with C were respectively detected. The expression of several enzymes in crucial points of regulation in glycolysis were up-regulated and DEGs were not significantly enriched in isopentenyl diphosphate (IPP) biosynthesis pathway. In addition, up-regulated genes of great regulatory importance in carbon fixation (Calvin cycle) were identified. Conclusions: The rapid acceleration of glycolytic pathway supplying precursors for the biosynthesis of IPP and natural rubber, instead of rubber biosynthesis per se, may be responsible for ethylene stimulation of latex yield in rubber tree. The elevated rate of flux throughout the Calvin cycle may account for some durability of ethylene-induced stimulation. Our finding lays the foundations for molecular diagnostic and genetic engineering for high-yielding improvement of rubber tree.