The small RNA profile in latex from Hevea brasiliensis trees is affected by tapping panel dryness

Abstract

Natural rubber is harvested by tapping Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. Harvesting stress can lead to tapping panel dryness (TPD). MicroRNAs (miRNAs) are induced by abiotic stress and regulate gene expression by targeting the cleavage or translational inhibition of target messenger RNAs. This study set out to sequence miRNAs expressed in latex cells and to identify TPD-related putative targets. Deep sequencing of small RNAs was carried out on latex from trees affected by TPD using Solexa technology. The most abundant small RNA class size was 21 nucleotides for TPD trees compared with 24 nucleotides in healthy trees. By combining the LeARN pipeline, data from the Plant MicroRNA database and Hevea EST sequences, we identified 19 additional conserved and four putative species-specific miRNA families not found in previous studies on rubber. The relative transcript abundance of the Hbpre-MIR159b gene increased with TPD. This study revealed a small RNA-specific signature of TPD-affected trees. Both RNA degradation and a shift in miRNA biogenesis are suggested to explain the general decline in small RNAs and, particularly, in miRNAs.

Genome-Wide Identification of MicroRNAs and Their Targets in the Leaves and Fruits of Eucommia ulmoides Using High-Throughput Sequencing

“…MIR159 targets four MYB proteins, which contain a conserved MYB DNA binding domain and are one of the larger group of plant protein family that play a regulatory role in developmental processes and defense responses (Wu and Poethig, 2006; Fornara and Coupland, 2009). In Arabidopsis , MYB transcription factors are involved in plant leaf development (Palatnik et al, 2003; Millar and Gubler, 2005), whereas in Hevea brasiliensis , a MYB transcription factor induces programmed cell death in rubber tree bark, and its expression is significantly decreased in the latex of trees affected by tapping panel dryness (Gébelin et al, 2013). MIR396 was predicted to target 17 growth-regulating factor genes encoding respective putative transcription factors, which play a regulatory role in plant growth and development as well as in defense responses (Wu and Poethig, 2006).…”

“…miRNAs also participate in regulating terpenoid accumulation through regulating their target genes, and in Arabidopsis thaliana and tomato, flavonoid biosynthesis is affected by the expression levels of miRNAs (Davuluri et al, 2005; Gou et al, 2011; Ng et al, 2011); miR6435, miR5021, and miR1134 are specifically expressed in glandular trichomes of Xanthium strumarium and play a role in the regulation of xanthanolide biosynthesis (Fan et al, 2015); and miR156, miR828, miR858, and miR5072 regulate anthocyanin accumulation in apple peels (Qu et al, 2016). The expression of miR159b regulates latex production in H. brasiliensis (Gébelin et al, 2013), and the negative regulation of hbr-miR172 results in a dramatic increase in latex yield of the rubber tree (Pramoolkit et al, 2014). Therefore, it is important to identify miRNAs and their target genes, which is essential to understanding miRNAs-mediated gene regulation of Eu-rubber biosynthesis.…”

The Hevea brasiliensis AP2/ERF superfamily: from ethylene signalling to latex harvesting and physiological disease response

“…The transcript of this gene was also 60% lower during the occurrence of TPD in comparison to normal condition (Venkatachalam et al, 2007). In their study, Gébelin et al (2013) predicted that the microRNA, HbmiR159b could target the Myb-like transcription factor (HbMyb1) and glutathione peroxidase (HbGPX) in Hevea brasiliensis. These post-transcriptional regulations may result in a change in the activity of target genes.…”

Identification, expression analysis, and potential roles of microRNAs in the regulation of polysaccharide biosynthesis in Polygonatum cyrtonema Hua

“…Additionally, miR156, miR828, miR858, and miR5072 regulate anthocyanin accumulation in apple peel [ 12]. In Brazilian rubber tree, miR159b regulates the production of latex [ 13]. Therefore, the identification of miRNAs and their target genes is essential for understanding the regulation of miRNA-mediated biosynthesis of polysaccharides in P. cyrtonema.…”