Anatomical comparison of branches and trunks of seven commercial wood species

Indonesia is a mega-biodiversity country that grows about 4000 timber producer tree species in tropical rain forest. The comprehensive information of wood properties and quality is important in managing the natural resources sustainably. However, stem in basic properties studies of wood from the natural forest is limited because of some difficulties in harvesting until the transportation process. Hence, study the wood branches becomes a solution, as sometimes wood core samples are not adequate. The question was whether the branch properties could represent the main stem properties? Wood anatomy is an important wood property that can predict the other properties, for instance, the physical and mechanical properties, that determine the effective use of this material. This paper aims to present the comparison of wood anatomical properties of branches and main stem of seven commercial wood species. Quantitative and qualitative anatomical structures were investigated according to the International Association of Wood Anatomist (IAWA) Committee. Result shows that the quantitative wood anatomy of four samples (Mimba, Leda, Jabon, and Bintangur) was statistically different, while only one parameter in Tusam, Mindi, and Khaya was different. Accordingly, it can be concluded that studying the wood properties could be carried out using branch effectively.

Transcriptome and miRNAome reveal components regulating primary thickening of bamboo shoots

Primary thickening determines bamboo yield and wood property. However, little is known about the regulatory networks involved in this process. The present study identified a total of 58,652 genes and 521 miRNAs via transcriptome and small RNA sequencing using the underground thickening shoot samples of wild type (WT) Moso bamboo (Phyllostachys edulis) and a thick wall (TW) variant (P. edulis cv. Pachyloen) at five developmental stages (WTS1/TWS1-WTS5/TWS5). A total of 11,636 (54.05%) differentially expressed genes (DEGs) and 515 (98.85%) differentially expressed miRNAs (DEmiRs) were identified from the WT, TW, and WTTW groups. The first two groups were composed of four pairwise combinations each between two successive stages (WTS2/TWS2_vs_WTS1/TWS1, WTS3/TWS3_vs_WTS2/TWS2, WTS4/TWS4_vs_WTS3/TWS3 and WTS5/TWS5_vs_WTS4/TWS4), and the WTTW group was composed of five between two relative stages (TWS1-5_vs_WTS1-5). Additionally, among the phytohormones, zeatin (ZT) showed more remarkable changes in concentrations than indole-3-acetic acid (IAA), gibberellic acid (GA3), and abscisic acid (ABA) throughout the five stages in the WT and the TW groups. Moreover, 118 sites were identified for 590 miRNA-mRNA pairs via degradome sequencing. The dual-luciferase reporter assay confirmed that 14 miRNAs bound to 12 targets. Fluorescence in situ hybridization (FISH) localized miR166 and miR160 in the shoot apical meristem (SAM) and the procambium of Moso bamboo shoots at the S1 stage. Thus, primary thickening is a complex process regulated by miRNA-gene-phytohormone networks, and the miRNAome and transcriptome dynamics regulate phenotypic plasticity. These findings provide insights into the molecular mechanisms underlying wood formation and properties and propose targets for bamboo breeding.

Association Study and Mendelian Randomization Analysis Reveal Effects of the Genetic Interaction Between PtoMIR403b and PtoGT31B-1 on Wood Formation in Populus tomentosa

MicroRNAs (miRNAs), important posttranscriptional regulators of gene expression, play a crucial role in plant growth and development. A single miRNA can regulate numerous target genes, making the determination of its function and interaction with targets challenging. We identified PtomiR403b target to PtoGT31B-1, which encodes a galactosyltransferase responsible for the biosynthesis of cell wall polysaccharides. We performed an association study and epistasis and Mendelian randomization (MR) analyses to explore how the genetic interaction between PtoMIR403b and its target PtoGT31B-1 underlies wood formation. Single nucleotide polymorphism (SNP)-based association studies identified 25 significant associations (P < 0.01, Q < 0.05), and PtoMIR403b and PtoGT31B-1 were associated with five traits, suggesting a role for PtomiR403b and PtoGT31B-1 in wood formation. Epistasis analysis identified 93 significant pairwise epistatic associations with 10 wood formation traits, and 37.89% of the SNP-SNP pairs indicated interactions between PtoMIR403b and PtoGT31B-1. We performed an MR analysis to demonstrate the causality of the relationships between SNPs in PtoMIR403b and wood property traits and that PtoMIR403b modulates wood formation by regulating expression of PtoGT31B-1. Therefore, our findings will facilitate dissection of the functions and interactions with miRNA-targets.

Near-infrared spectroscopy and hyperspectral imaging can aid in the prediction and mapping of polyploid acacia hybrid wood properties in tree improvement programs

Acacia, including Acacia hybrids, are some of the most important species grown as part of the Vietnamese wood industry. Rapid methods to identify the variations in the wood properties of Acacia hybrids however, are a currently lacking and creating limits for their breeding programs. In this study, nine Acacia hybrid clones, including those that were diploid, triploid, and tetraploid were evaluated using near-infrared spectroscopy (NIR) and hyperspectral imaging (HSI). The standard normal variate (SNV) and second derivative (SP2D) were applied to compare the performances of NIR and HSI using partial least square regression. The HSI images were acquired at wavelengths from 1033 to 2230 nm and the SNV and SP2D described the variations in the wood properties. The NIR predicted the wood physical properties better than HSI, while they provided similar predictions for the mechanical properties. The mapping results showed low densities around the pith area and high densities near the bark. They also revealed that the air-dry moisture content changed at different positions within a disk and was dependent on its position within the tree. Overall, NIR and HSI were found to be potential wood property prediction tools, suitable for use in tree improvement programs.

Spectrometric prediction of wood basic density by comparison of different grain angles and variable selection methods

Background Wood basic density (WBD) is one of the most crucial wood property in tree and mainly determined the end use of wood for industry. However, the measurement WBD is time- and cost-consuming, which an alternatively fast and no-destructive measurement is needed. In this study, capability of NIR spectroscopy combined with partial least squares regression (PLSR) to quantify the WBD were examined in multiple wood species. To obtain more accurate and robust prediction models, the grain angle (0° (transverse surface), 45°, 90° (radial surface)) influence on the collection of solid wood spectra and a comparison of found variable selection methods for NIR spectral variables optimization were conducted, including significant Multivariate Correlation (sMC), Regularized elimination procedure (Rep), Iterative predictor weighting (Ipw) and Genetic algorithm (Ga). Models made by random calibration data selection were conducted 200 times performance evaluation. Results These results indicate that 90° angle models display relatively highest efficiency than other angle models, mixed angle model yield a satisfied WBD prediction results as well and could reduce the influence of grain angle. Rep method shows a higher efficiency than other methods which could eliminate the uninformative variables and enhance the predictive performance of 90° angle and mix angle models. Conclusions This study is potentially shown that the WBD (g/cm3) on solid wood across grain angles and varies wood species could be measured in a rapid and efficient way using NIR technology. Combined with the PLSR model, our methodology could serve as a tool for wood properties breeding and silviculture study.