Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture and Rural Affairs, Fujian Agriculture and Forestry University, Fuzhou, 350002, Fujian, China.
Fuzhou Institute of Agricultural Sciences, Fuzhou, 350018, Fujian, China.
BMC Plant Biol. 2022 May 19;22(1):247. doi: 10.1186/s12870-022-03641-6.
Sugarcane mosaic disease (SMD) is a major viral disease of sugarcane (Saccharum spp.) worldwide. Sorghum mosaic virus (SrMV) is the dominant pathogen of SMD in the sugarcane planting areas of China. There is no report on miRNAs and their regulatory networks in sugarcane response to SrMV infection.
In this study, small RNA sequencing (sRNA-seq) of samples from the leaves of SMD-susceptible variety ROC22 and -resistant variety FN39 infected by SrMV was performed. A total of 132 mature miRNAs (55 known miRNAs and 77 novel miRNAs) corresponding to 1,037 target genes were identified. After the SrMV attack, there were 30 differentially expressed miRNAs (17 up-regulated and 13 down-regulated) in FN39 and 19 in ROC22 (16 up-regulated and 3 down-regulated). Besides, there were 18 and 7 variety-specific differentially expressed miRNAs for FN39 and ROC22, respectively. KEGG enrichment analysis showed that the differentially expressed miRNAs targeted genes involved in several disease resistance-related pathways, such as mRNA surveillance, plant pathway interaction, sulfur metabolism, and regulation of autophagy. The reliability of sequencing data, and the expression patterns / regulation relationships between the selected differentially expressed miRNAs and their target genes in ROC22 and FN39 were confirmed by quantitative real-time PCR. A regulatory network diagram of differentially expressed miRNAs and their predicted target genes in sugarcane response to SrMV infection was sketched. In addition, precursor sequences of three candidate differentially expressed novel miRNAs (nov_3741, nov_22650 and nov_40875) were cloned from the ROC22 leaf infected by SrMV. Transient overexpression demonstrated that they could induce the accumulation of hydrogen peroxide and the expression level of hypersensitive response marker genes, salicylic acid-responsive genes and ethylene synthesis-depended genes in Nicotiana benthamiana. It is thus speculated that these three miRNAs may be involved in regulating the early immune response of sugarcane plants following SrMV infection.
This study lays a foundation for revealing the miRNA regulation mechanism in the interaction of sugarcane and SrMV, and also provides a resource for miRNAs and their predicted target genes for SrMV resistance improvement in sugarcane.
甘蔗花叶病（SMD）是全球甘蔗（Saccharum spp.）的一种主要病毒性疾病。高粱花叶病毒（SrMV）是中国甘蔗种植区 SMD 的主要病原体。目前尚无关于 miRNA 及其在甘蔗对 SrMV 感染反应中的调控网络的报道。
本研究对受 SrMV 感染的感病品种 ROC22 和抗病品种 FN39 叶片进行了小 RNA 测序（sRNA-seq）分析。共鉴定到 132 个成熟 miRNA（55 个已知 miRNA 和 77 个新 miRNA），对应 1037 个靶基因。在 SrMV 攻击后，FN39 中有 30 个差异表达 miRNA（17 个上调和 13 个下调），ROC22 中有 19 个（16 个上调和 3 个下调）。此外，FN39 和 ROC22 分别有 18 个和 7 个品种特异性差异表达 miRNA。KEGG 富集分析表明，差异表达 miRNA 靶向的基因参与了几种与疾病抗性相关的途径，如 mRNA 监测、植物途径相互作用、硫代谢和自噬调控。通过定量实时 PCR 验证了测序数据的可靠性，以及所选差异表达 miRNA 及其在 ROC22 和 FN39 中靶基因的表达模式/调控关系。构建了甘蔗对 SrMV 感染反应中差异表达 miRNA 及其预测靶基因的调控网络示意图。此外，从受 SrMV 感染的 ROC22 叶片中克隆了三个候选差异表达新 miRNA（nov_3741、nov_22650 和 nov_40875）的前体序列。瞬时过表达表明，它们可以诱导烟草原生质体中过氧化氢的积累和过敏反应标记基因、水杨酸响应基因和乙烯合成依赖性基因的表达水平。因此，推测这三个 miRNA 可能参与调节甘蔗植物感染 SrMV 后的早期免疫反应。
本研究为揭示 miRNA 在甘蔗与 SrMV 相互作用中的调控机制奠定了基础，也为甘蔗 SrMV 抗性改良中的 miRNA 及其预测靶基因提供了资源。
