A miR398a precursor was cloned and its expression level was analyzed for elucidating the role of miR398a during longan somatic embryogenesis. The miR398a precursor was isolated by RT -PCR and its transcription levels were detected in longan embryogenic cultures at different developmental stages by real-time RT-PCR. The length of the miR398a precursor (GenBank loucs FJ973472)was 83 bp, including 21 bp mature sequence of miR398a. qPCR results indicated that the miR398a precursor was expressed in most of the tissues in longan embryogenic cultures at different developmental stages. The expression quantity of the miR398a precursor was incomplete compact pro-embryogenic cultures>globular embryos >compact pro-embryogenic cultures>embryogenic callus II >friable-embryogenic callus >Cotyledonary embryos >heart -shaped embryos >torpedo-shaped embryos. Longan miR398a precursor was highly conserved among different species and expressed with tissue specific and sequential characteristics during longan somatic embryogenesis.%为了解miR398a在龙眼体胚发生中的调控机制,以龙眼胚性愈伤组织为材料,采用RT-PCR法克隆miR398a前体序列,最终成功克隆了长83 bp的龙眼miR398a前体序列(GenBank登录号:FJ973472):该前体与其它物种的miR398前体序列具有较高的同源性,并包含miR398a的成熟序列；利用qPCR技术研究该基因在龙眼体胚发生发育过程中的表达情况,定量分析结果表明,随着龙眼体胚的发育,pre-miR398a在不同胚性培养物中的转录水平存在显著差异:在不完全胚性紧实结构表达量最高,球形胚阶段次之,随后是胚性紧实球形结构、胚性愈伤组织Ⅱ及松散型胚性愈伤组织,在心形胚、鱼雷形胚阶段和子叶形胚阶段表达量较低.说明pre-miR398a在龙眼体胚发生过程中的表达具有组织特异性和-定的时序性.
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