Expression Patterns and Regulation of Non-Coding RNAs during Synthesis of Cellulose in Eucalyptus grandis Hill

Abstract

Cellulose, an essential structural component in the plant cell wall and a renewable biomass resource, plays a significant role in nature. Eucalyptus’s excellent timber tree species (including Eucalyptus grandis Hill) provide many raw materials for the paper and wood industries. The synthesis of cellulose is a very complex process involving multiple genes and regulated by various biological networks. However, research on regulating associated genes and non-coding RNAs during cellulose synthesis in E. grandis remains lacking. In this study, the wood anatomical characteristics and chemical indexes of E. grandis were analyzed by taking three different parts (diameter at breast height (DBH), middle and upper part of the trunk) from the main stem of E. grandis as raw materials. The role of non-coding RNAs (Long non-coding RNA, lncRNA; Micro RNA, miRNA; Circle RNA, circRNA) on regulating candidate genes was presented, and the network map of ceRNA (Competing endogenous RNA) regulation during wood cellulose biosynthesis of E. grandis was constructed. The transcriptome sequencing of nine samples obtained from the trunk of the immature xylem in E. grandis at DBH, middle and upper parts had a 95.81 G clean reading, 57,480 transcripts, 7365 lncRNAs, and 5180 circRNAs. Each sample had 172–306 known miRNAs and 1644–3508 new miRNAs. A total of 190 DE-lncRNAs (Differentially expressed long non-coding RNAs), 174 DE-miRNAs (Differentially expressed micro RNAs), and 270 DE-circRNAs (Differentially expressed circle RNAs) were obtained by comparing transcript expression levels. Four lncRNAs and nine miRNAs were screened out, and the ceRNA regulatory network was constructed. LncRNA1 and lncRNA4 regulated the genes responsible for cellulose synthesis in E. grandis, which were overexpressed in 84K (Populus Alba × Populus glandulosa) poplar. The cellulose and lignin content in lncRNA4-oe were significantly higher than wild type 84K poplar and lncRNA1-oe. The average plant height, middle and basal part of the stem diameter in lncRNA4-oe were significantly higher than the wild type. However, there was no significant difference between the growth of lncRNA1-oe and the wild type. Further studies are warranted to explore the molecular regulatory mechanism of cellulose biosynthesis in Eucalyptus species.

Identification and Functional Prediction of CircRNAs in Leaves of F1 Hybrid Poplars with Different Growth Potential and Their Parents

“…We statistically analyzed the number and expression level of SPE circRNAs in the F1 hybrids with significant difference between the male parent and female parent control groups and found that there were 92 SPE circRNAs in 119 DECs, among which the number of SPE-F circRNAs (60) was more than that of SPE-M circRNAs (32) (Figure 3B). In addition to Y3H3, the number of SPE circRNAs in F1 hybrids with high growth potential (44)(45)(46)(47)(48)(49)(50)(51) was more than that in the F1 hybrids with low growth potential (27)(28)(29)(30)(31)(32)(33) and in the male parents (32), while the number of SPE-M circRNAs in the F1 hybrids with low growth potential (14)(15) was more than that in the F1 hybrids with high growth potential (8) (Figure 3B). Except for Y3H3, the expression pattern of SPE-M circR-NAs of the F1 hybrids with high growth potential was similar to that of the female parent, while that of the F1 hybrids with low growth potential was similar to that of male parent (Figure 3C).…”

“…These DECs might affect the heterosis of poplar by regulating the biological processes closely related to plant growth and development, such as carbohydrate metabolism and amino acid metabolism. Except for the common non-additively expressed circRNAs of the F1 hybrids with high growth potential, which had only one representative in the dark red module (1), the common non-additively expressed circRNAs of the F1 hybrids with high growth potential (11, in pink module), common non-additive circRNAs of low growth potential F1 hybrids (11)(12)(13)(14), and common DECs of F1 hybrid with different growth potentials (7-17) had more representatives in both modules (Figure 7C). There were significantly more SPE circRNAs in the pink module (17) than in dark red module (1), especially SPE-F circRNAs.…”

Seasonal and Depth Dynamics of Soil Moisture Affect Trees on the Tibetan Plateau

“…During the conversion of sucrose produced by tree photosynthesis to cellulose, it undergoes a partial oxygen isotope signal exchange in the source water [48]. In other words, the δ 18 O TR keeps the mixed signal of source water and leaf evaporation [49]. These two processes result in a higher δ 18 O TR in arid areas.…”

Season and depth differences of soil moisture use for tree growth across wet and dry gradients in the Tibetan Plateau

“…On the other hand, soil water evaporation is enhanced in arid environments and the source water absorbed by tree roots becomes heavier, leading to an enrichment of oxygen isotopes in leaf water (Roden et al 2000). Sucrose produced by photosynthesis is transported through the bast to the xylem of the trunk for cellulose synthesis, and during the conversion to cellulose, oxygen isotopes in the sugar are partially exchanged with oxygen isotopes in the source water (Zhan et al 2021), resulting in a mixed signal of both source water and transpiration-enriched oxygen isotopes in the cellulose oxygen isotope ratio of the tree-ring (Giraldo et al, 2022). These two processes result in a higher δ 18 O TR in arid areas than in humid areas.…”