Abstract Litchi (Litchi chinensis Sonn.) has a short shelf life and its storability varies greatly among different cultivars. In this study, four litchi cultivars of different storability were used to investigate the possible roles of microRNAs and their targets in litchi fruit senescence. Slower pericarp browning in ‘Jingganghongnuo’ and ‘Huaizhi’ was observed compared with that in ‘Guiwei’ and ‘Nuomici’, which was correlated with higher levels of ATP, energy charge, and anthocyanin but lower activity of anthocyanase that oxidizes anthocyanin. A phylogenic analysis of Arabidopsis, tomato (Solanum lycopersicum), and litchi, using totally 40 LcMYBs, categorized certain LcMYBs into the anthocyanin biosynthesis-related R2R3 MYB subfamilies as previously described in Arabidopsis. In addition, the expression of a group of litchi miRNAs, including miR159/319, miR828 and miR858 that jointly target multiple LcMYB genes, was found to decrease fast in ‘Jingganghongnuo’ and ‘Huaizhi’. A group of R2R3-type LcMYBs was validated as authentic targets of these miRNAs. Accordingly, these MYBs were induced in ‘Jingganghongnuo’ and ‘Huaizhi’ whereas largely suppressed in ‘Guiwei’ and ‘Nuomici’. Moreover, litchi miR2118 targeting energy-related genes displayed a similar expression pattern to those of the MYB-targeting miRNAs in the different cultivars, and two of the miR2118 targets exhibited opposite expression pattern with miR2118. Finally, a miRNA-mediated anthocyanin and energy metabolism network underlying the regulation of cultivar-specific fruit senescence in litchi is proposed. We conclude that miRNA-mediated regulation can account for the differential storability of specific litchi cultivars.

中文翻译：

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miRNA介导的花青素和能量代谢对荔枝果实耐贮性的影响

摘要 荔枝（Litchi chinensis Sonn.）保质期短，不同品种的耐贮性差异很大。在本研究中，使用四种不同耐贮性的荔枝品种来研究 microRNA 及其靶标在荔枝果实衰老中的可能作用。与'桂味'和'糯米'相比，'井冈红糯'和'槐枝'的果皮褐变较慢，这与较高水平的ATP、能量电荷和花青素有关，但氧化花青素的花青素酶活性较低。拟南芥、番茄 (Solanum lycopersicum) 和荔枝的系统发育分析使用总共 40 个 LcMYB，将某些 LcMYB 分类为与花青素生物合成相关的 R2R3 MYB 亚科，如先前在拟南芥中所述。此外，一组荔枝miRNA的表达，发现联合靶向多个 LcMYB 基因的 miR159/319、miR828 和 miR858 在“井冈红诺”和“怀智”中快速减少。一组 R2R3 型 LcMYB 被验证为这些 miRNA 的真实靶点。因此，这些MYBs在'井冈红糯'和'怀智'中被诱导，而在'贵味'和'糯米'中被大量抑制。此外，荔枝 miR2118 靶向能量相关基因的表达模式与不同品种中靶向 MYB 的 miRNA 的表达模式相似，其中两个 miR2118 靶标表现出与 miR2118 相反的表达模式。最后，提出了一个 miRNA 介导的花青素和能量代谢网络，该网络是调控荔枝品种特异性果实衰老的基础。