Genome-scale mRNA and small RNA transcriptomic insights into initiation of citrus apomixis.
Genome-scale mRNA and small RNA transcriptomic insights into initiation of citrus apomixis.
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柑橘无性生殖起始的基因组规模 mRNA 和小 RNA 转录组学见解
DOI：
10.1093/jxb/erw338
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发表时间：
2016-10
影响因子：
6.9
通讯作者：
Guo WW
中科院分区：
文献类型：
--
作者：
Long JM;Liu Z;Wu XM;Fang YN;Jia HH;Xie ZZ;Deng XX;Guo WW
多胚胚珠和单胚胚珠之间的整合mRNA和小RNA分析揭示了柑橘无融合生殖启动中氧化应激反应和新型miRNA靶调控模块的参与。珠心胚（NE）是柑橘无融合生殖的一种不定形式，其中无性胚直接由胚囊周围的珠心细胞产生。NE使理想的农艺性状的固定和无性系后代的生产脱毒砧木，但阻碍了杂交育种的进展。尽管NE在柑橘育种和商业生产中具有重要意义，但对其潜在的分子机制知之甚少。通过组织学观察，对两个多胚柑橘品种的珠心胚发生时期进行了研究。为了探索NEI相关的基因和调控途径，我们对两对品种在NEI之前和期间的胚珠进行了mRNA-seq和sRNA-seq分析。在多胚胚珠和单胚胚珠之间共鉴定出305个差异表达基因。基因本体（GO）分析表明，几个过程显着丰富的DEG的基础上。特别是，对压力的反应，尤其是对氧化应激的反应，在多胚胚珠中表现得过多。近150个miRNAs，包括约90个保守的和约60个新的miRNAs，在任一品种对的胚珠中被鉴定。仅鉴定了两种差异表达的miRNA（DEM），其中新的miRN 23 - 5 p被抑制，而靶标在多胚胚珠中积累。对柑橘多胚胚珠和单胚胚珠之间转录和转录后调控模式的综合研究为NE的作用机制提供了新的认识，有助于揭示植物无融合生殖的调控机制。
Integrative mRNA and small RNA analysis between poly- and monoembryonic ovules reveals involvement of an oxidative stress response and a novel miRNA-target regulatory module in initiation of citrus apomixis. Nucellar embryony (NE) is an adventitious form of apomixis common in citrus, wherein asexual embryos initiate directly from nucellar cells surrounding the embryo sac. NE enables the fixation of desirable agronomic traits and the production of clonal offspring of virus-free rootstock, but impedes progress in hybrid breeding. In spite of the great importance of NE in citrus breeding and commercial production, little is understood about the underlying molecular mechanisms. In this study, the stages of nucellar embryo initiation (NEI) were determined for two polyembryonic citrus cultivars via histological observation. To explore the genes and regulatory pathways involved in NEI, we performed mRNA-seq and sRNA-seq analyses of ovules immediately prior to and at stages during NEI in the two pairs of cultivars. A total of 305 differentially expressed genes (DEGs) were identified between the poly- and monoembryonic ovules. Gene ontology (GO) analysis revealed that several processes are significantly enriched based on DEGs. In particular, response to stress, and especially response to oxidative stress, was over-represented in polyembryonic ovules. Nearly 150 miRNAs, comprising ~90 conserved and ~60 novel miRNAs, were identified in the ovules of either cultivar pair. Only two differentially expressed miRNAs (DEMs) were identified, of which the novel miRN23-5p was repressed whereas the targets accumulated in the polyembryonic ovules. This integrated study on the transcriptional and post-transcriptional regulatory profiles between poly- and monoembryonic citrus ovules provides new insights into the mechanism of NE, which should contribute to revealing the regulatory mechanisms of plant apomixis.