rubber biosynthesis
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2022 ◽  
Vol 12 ◽  
Author(s):  
Hui-Liang Li ◽  
Ying Wang ◽  
Dong Guo ◽  
Jia-Hong Zhu ◽  
Shi-Qing Peng

The rubber tree (Hevea brasiliensis Muell. Arg.) is a tropical tree species that produce natural rubber. Self-rooted juvenile clones (SRJCs) are novel rubber tree planting materials developed through primary somatic embryogenesis. SRJCs have a higher rubber yield compared with donor clones (DCs). The molecular basis underlying increased rubber yield in SRJCs remains largely unknown. Here, the latex from SRJCs and DCs were collected for strand-specific and small RNA-seq methods. A total of 196 differentially expressed long noncoding RNAs (DELs), and 11 differentially expressed microRNAs were identified in latex between SRJCs and DCs. Targeted genes of DELs were markedly enriched for various biological pathways related to plant hormone signal transduction, photosynthesis, glutathione metabolism, and amino acids biosynthesis. DELs probably acted as cis-acting regulation was calculated, and these DELs relevant to potentially regulate rubber biosynthesis, reactive oxygen species metabolism, and epigenetic modification. Furthermore, the DELs acting as microRNA targets were studied. The interaction of microRNA and DELs might involve in the regulation of natural rubber biosynthesis.


2021 ◽  
Author(s):  
Hui Liu ◽  
Yiyu Hu ◽  
Kun Yuan ◽  
Chengtian Feng ◽  
Qiguang He ◽  
...  

Abstract Noncoding RNAs (ncRNAs) play pivotal roles in various biological processes in plants. However, the role of ncRNAs in tapping panel dryness (TPD) of rubber tree (Hevea brasiliensis) is largely unknown. Here, the whole transcriptomes of bark tissues from healthy and TPD trees were performed to identify differentially expressed long ncRNAs (DELs), microRNAs/miRNA (DEMs), genes (DEGs), and their regulatory networks involved in TPD. A total of 263 DELs, 174 DEMs, and 1,574 DEGs were identified in the bark of TPD tree compared with that of healthy tree. KEGG analysis revealed that most of the DEGs and targets of DELs and DEMs were mainly enriched in metabolic pathways, biosynthesis of secondary metabolites, and plant hormone signal transduction. Additionally, the majority of DEGs and DELs related to rubber biosynthesis were down-regulated in TPD trees. Furthermore, 98 DEGs and 44 DELs were targeted by 54 DEMs, 190 DEGs were identified as putative targets of 56 DELs, and two and 44 DELs were predicted as precursors and endogenous target mimics (eTMs) of two and six DEMs, respectively. Based on these, the DEL-DEM-DEG regulatory network involved in TPD was constructed, and 13 hub DELs, three hub DEMs and two hub DEGs were identified. The results provide novel insights into the regulatory roles of ncRNAs underlying TPD and lay a foundation for future functional characterization of lncRNAs, miRNAs, and genes involved in TPD in rubber tree.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Shichao Xin ◽  
Yuwei Hua ◽  
Ji Li ◽  
Xuemei Dai ◽  
Xianfeng Yang ◽  
...  

Abstract Background The processabilities and mechanical properties of natural rubber depend greatly on its molecular weight (MW) and molecular weight distribution (MWD). However, the mechanisms underlying the regulation of molecular weight during rubber biosynthesis remain unclear. Results In the present study, we determined the MW and particle size of latex from 1-year-old virgin trees and 30-year-old regularly tapped trees of the Hevea clones Reyan7-33–97 and RRIM600. The results showed that both the MW and the particle size of latex varied between these two clones and increased with tree age. Latex from RRIM600 trees had a smaller average particle size than that from Reyan7-33–97 trees of the same age. In 1-year-old trees, the Reyan7-33–97 latex displayed a slightly higher MW than that of RRIM600, whereas in 30-year-old trees, the RRIM600 latex had a significantly higher MW than the Reyan7-33–97 latex. Comparative analysis of the transcriptome profiles indicated that the average rubber particle size is negatively correlated with the expression levels of rubber particle associated proteins, and that the high-MW traits of latex are closely correlated with the enhanced expression of isopentenyl pyrophosphate (IPP) monomer-generating pathway genes and downstream allylic diphosphate (APP) initiator-consuming non-rubber pathways. By bioinformatics analysis, we further identified a group of transcription factors that potentially regulate the biosynthesis of IPP. Conclusions Altogether, our results revealed the potential regulatory mechanisms involving gene expression variations in IPP-generating pathways and the non-rubber isoprenoid pathways, which affect the ratios and contents of IPP and APP initiators, resulting in significant rubber MW variations among same-aged trees of the Hevea clones Reyan7-33–97 and RRIM600. Our findings provide a better understanding of rubber biosynthesis and lay the foundation for genetic improvement of rubber quality in H. brasiliensis.


2021 ◽  
Author(s):  
Shichao Xin ◽  
Yuwei Hua ◽  
Ji Li ◽  
Xuemei Dai ◽  
Xianfeng Yang ◽  
...  

Abstract Background: The processabilities and mechanical properties of natural rubber depend greatly on its molecular weight (MW) and molecular weight distribution (MWD). However, the mechanisms underlying the regulation of molecular weight during rubber biosynthesis remain unclear. Results: In the present study, we determined the MW and particle size of latex from 1-year-old virgin trees and 30-year-old regularly tapped trees of the Hevea clones Reyan7-33-97 and RRIM600. The results showed that both the MW and the particle size of latex varied between these two clones and increased with tree age. Latex from RRIM600 trees had a smaller average particle size than that from Reyan7-33-97 trees of the same age. In 1-year-old trees, the Reyan7-33-97 latex displayed a slightly higher MW than that of RRIM600, whereas in 30-year-old trees, the RRIM600 latex had a significantly higher MW than the Reyan7-33-97 latex. Comparative analysis of the transcriptome profiles indicated that the average rubber particle size is negatively correlated with the expression levels of rubber particle associated proteins, and that the high-MW traits of latex are closely correlated with the enhanced expression of isopentenyl pyrophosphate (IPP) monomer-generating pathway genes and downstream allylic diphosphate (APP) initiator-consuming non-rubber pathways. By bioinformatics analysis, we further identified a group of transcription factors that potentially regulate the biosynthesis of IPP. Conclusions: Altogether, our results revealed the potential regulatory mechanisms involving gene expression variations in IPP-generating pathways and the non-rubber isoprenoid pathways, which affect the ratios and contents of IPP and APP initiators, resulting in significant rubber MW variations among same-aged trees of the Hevea clones Reyan7-33-97 and RRIM600. Our findings provide a better understanding of rubber biosynthesis and lay the foundation for genetic improvement of rubber quality in H. brasiliensis.


2021 ◽  
Author(s):  
Yujie Fan ◽  
Xiaohu Xiao ◽  
Jianghua Yang ◽  
Jiyan Qi ◽  
Yi Zhang ◽  
...  

Abstract Background: Natural rubber, an important industrial raw material with wide applications, is harvested in the form of latex (cytoplasm of rubber-producing laticifers) from Hevea brasiliensis (para rubber tree) by the way of tapping, i.e. removing a slice of trunk bark by a special knife. In regularly tapped rubber trees, latex regeneration consists of one of the main yield-limiting factors for rubber productivity. Conspicuous stimulation on latex production for the first few tappings makes virgin (untapped before) rubber trees an ideal model to investigate the regulatory mechanisms of latex regeneration. To understand the underlying mechanisms, genome-wide transcript profiling was conducted with a silver-staining cDNA-AFLP technology against the latex samples for the first five tappings.Results: A total of 505 non-redundant differentially expressed (DE) transcript-derived fragments (TDFs) were identified, of which 217 were up-regulated, 180 down-regulated, and 108 bell type-regulated among the five tappings. About 72.5% of these DE-TDFs were functionally annotated, and classified into 11 functional categories, which were discussed with reference to harvesting-stimulated latex regeneration. The importance of sugar metabolism and rubber biosynthesis was highlighted, due to the fact that most of the DE-TDFs annotated in sucrose transport, sugar catabolism, glycolysis, tricarboxylic acid cycle and pentose-phosphate pathway and nine of the ten rubber biosynthesis pathway DE-TDFs were up-regulated by the tapping treatment. More than one tenth of the total DE-TDFs were randomly selected for expression validation by semi-quantitative RT-PCR, and 83.8% showed patterns consistent with their original cDNA-AFLP gel profiles. Moreover, quantitative RT-PCR analysis revealed an 89.7% consistency for the 29 latex-regeneration related DE-TDFs examined.Conclusions: In brief, our results indicate the tapping treatment incurs extensive physiological and molecular changes in the laticifers of virgin rubber trees. The vast numbers of tapping-responsive DE-TDFs identified here provide a basis for unravelling the gene regulatory network for latex regeneration in regularly harvested rubber trees.


2021 ◽  
Vol 68 (1) ◽  
pp. 31-45
Author(s):  
A. Yu. Amerik ◽  
Yu. Ts. Martirosyan ◽  
L. Yu. Martirosyan ◽  
V. M. Goldberg ◽  
K. R. Uteulin ◽  
...  

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