Identification of miRNA–mRNA Regulatory Modules Involved in Lipid Metabolism and Seed Development in a Woody Oil Tree (Camellia oleifera)

Abstract

Tea oil camellia (Camellia oleifera), an important woody oil tree, is a source of seed oil of high nutritional and medicinal value that is widely planted in southern China. However, there is no report on the identification of the miRNAs involved in lipid metabolism and seed development in the high- and low-oil cultivars of tea oil camellia. Thus, we explored the roles of miRNAs in the key periods of oil formation and accumulation in the seeds of tea oil camellia and identified miRNA–mRNA regulatory modules involved in lipid metabolism and seed development. Sixteen small RNA libraries for four development stages of seed oil biosynthesis in high- and low-oil cultivars were constructed. A total of 196 miRNAs, including 156 known miRNAs from 35 families, and 40 novel miRNAs were identified, and 55 significantly differentially expressed miRNAs were found, which included 34 upregulated miRNAs, and 21 downregulated miRNAs. An integrated analysis of the miRNA and mRNA transcriptome sequence data revealed that 10 miRNA–mRNA regulatory modules were related to lipid metabolism; for example, the regulatory modules of ath-miR858b–MYB82/MYB3/MYB44 repressed seed oil biosynthesis, and a regulation module of csi-miR166e-5p–S-ACP-DES6 was involved in the formation and accumulation of oleic acid. A total of 23 miRNA–mRNA regulatory modules were involved in the regulation of the seed size, such as the regulatory module of hpe-miR162a_L-2–ARF19, involved in early seed development. A total of 12 miRNA–mRNA regulatory modules regulating growth and development were identified, such as the regulatory modules of han-miR156a_L+1–SPL4/SBP2, promoting early seed development. The expression changes of six miRNAs and their target genes were validated using quantitative real-time PCR, and the targeting relationship of the cpa-miR393_R-1–AFB2 regulatory module was verified by luciferase assays. These data provide important theoretical values and a scientific basis for the genetic improvement of new cultivars of tea oil camellia in the future.

Comparative transcriptomics analysis of developing peanut (Arachis hypogaea L.) pods reveals candidate genes affecting peanut seed size

“…It has been previously reported that in some legume crops, MYB and ARF are involved in seed size/weight determination (Gupta et al, 2017;Khemka et al, 2021). Dwindling in MYB82, MYB3, and MYB44 expression was found to be concurrent with seed size enlargement in rapeseed seeds, corroborating evidence was also obtained in MYB89, overexpressing of which attenuated seed yield in Arabidopsis (Li et al, 2017;Wu et al, 2021). In agreement with these previous studies, we found that the expression of MYB20 (arahy.UFA08L and arahy.D23SI7) exhibited gradual decline along with the peanut seed development over time, and also it showed relatively lower expression level in large-grain genotypes than in smallgrain genotypes at a given developmental stage, suggesting a negative regulatory role during pod development stages.…”

Identification of Camellia oleifera WRKY transcription factor genes and functional characterization of CoWRKY78

“…Two C. oleifera cultivars, MY53 (anthracnose-resistant cultivar) and MY01 (anthracnose-susceptible cultivar) were grown at the C. oleifera orchard in Yuping Dong Autonomous County, China (N27°17′, E108°54′). The annual mean temperature and precipitation were 16.4°C (61.52°F) and 1174.1 mm ( Wu et al., 2022 ). These two cultivars had similar genetic backgrounds, but different resistance to anthracnose.…”

“…Tissues from the root, stem, leaf, and peel were collected from C. oleifera to analyze the tissue-specific expression. As previously described, RNA isolation, cDNA synthesis followed by quantitative real-time RT-PCR (qRT-PCR) analysis were conducted ( Wu et al., 2022 ). Gene expression level was determined via the 2 −ΔΔCt method, and EF 1α and GAPDH were used as the housekeeping gene.…”

“…As one kind of oil-rich seed tree, C. oleifera has great economic value, nutritional and medicinal value because its seed oil is rich in unsaturated fatty acids and natural bioactive ingredients ( Ye et al., 2021 ). In the past several years, most C. oleifera studies have focused mainly on oil extraction technology ( Zhang et al., 2019a ), self-incompatibility ( Zhou et al., 2020 ), seed oil biosynthesis ( Zhang et al., 2021 ), seed development ( Wu et al., 2022 ), and fruit development ( He et al., 2022a ). Specifically, with ecological value, C. oleifera can not only live in the cold climate ( Wu et al., 2020 ), but also grow well in drought and barren soil ( He et al., 2022b ).…”

Effects of post-harvest natural drying on seed quality and endogenous hormones of Camellia oleifera

“…Seeds need to be stored after harvest, which has a high moisture content, so they should be dried. Furthermore, for some oil crops and fruits, post-harvest drying is also conducive to the transformation of oil or other beneficial substances (Baud et al, 2002;Borek et al, 2009;Ojediran et al, 2021;Wu et al, 2022). In hazelnut, the protein content has a gradual reduction, and the monounsaturated fatty acid content has a gradual increase with the increase in post-harvest drying time (Ali, 2018).…”