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.
Highlights
Licensee MDPI, Basel, Switzerland.Tea oil camellia (Camellia oleifera Abel.) is an important woody oil tree in southernChina and has a cultivation history of over two thousand years
The results show that the target genes were classified into three categories by the hypergeometric distribution algorithm (Figure 6a): biological process, cellular component, and molecular function
The major biological functions of differentially expressed target genes were identified by the significant terms in the gene ontology (GO) enrichment analysis; these results show that a total of 107 significant GO terms were related to the nucleus, sequence-specific DNA binding, and
Summary
Licensee MDPI, Basel, Switzerland.Tea oil camellia (Camellia oleifera Abel.) is an important woody oil tree in southernChina and has a cultivation history of over two thousand years. Tea oil camellia (Camellia oleifera Abel.) is an important woody oil tree in southern. Olive, and coconut, tea oil camellia is well known as one of the four major woody oil trees in the world [1,2]. Tea oil camellia seeds have a high oil content of up to 40%; are rich in unsaturated fatty acids (the oleic acid content accounts for over 75% of all the fatty acids in the oil of the seeds); exhibit an abundance of bioactive compounds, such as published maps and institutional affil-. The seed yield of tea oil camellia is not stable, and the seed oil content varies greatly among different germplasms, which seriously restricts the sustainable development of the tea oil camellia industry. One important strategy is the breeding of tea oil camellia cultivars with high seed oil contents and high and stable seed yields
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