苎麻纤维不同发育时期差异表达miRNAs的表达谱分析

miRNA在植物生长发育过程中起着重要的调控作用。本研究从苎麻纤维伸长期和胞壁加厚、端壁溶合期的中苎1号苎麻韧皮组织为材料的miRNA芯片中筛选出3个差异表达的miRNAs：miRl450、miRl56h和miRl72bl。利用半定量RT—PCR技术对3个差异表达miRNAs在4个苎麻纤维发育时期（苎麻纤维分生期，纤维伸长期，胞壁加厚端壁融合期和纤维成熟期）的韧皮组织以及花、叶、根和地下茎等组织和器官中的表达情况进行研究。结果表明供试的3个miRNA在苎麻纤维伸长期和胞壁加厚端壁融合期的表达量均为差异表达，进一步验证了芯片结果，其中mi1450在纤维成熟期表达量最高，在纤维伸长期的表达量最低；mi156h在花、地下茎、根和叶中的表达量显著高于4个苎麻纤维发育时期；mi172bl在纤维分生期的表达量最高，在花中的表达量最低。本研究建立了苎麻miRNA的茎环RT．PCR检测体系，为进一步研究miRNA在苎麻纤维发育过程中的作用奠定了基础。

The Expression Profile Analysis of Differentially Expressed miRNAs in Ramie Phloem Tissue at Different Fiber Development Stages

miRNA play important roles on plant growth and development process. Three miRNAs （including miR 1450, miR 156h and miR172b 1） with differential expression level were selected based on the results of miRNA chips, which comparing the miRNA expression between elongating period and cell wall thickening and end wall dissolving period of ramie fiber, and studied by semi-quantitative RT-PCR through stem-loop method. The expres- sion profiles were analyzed in ramie tissues and organs which including phloem tissues of four fiber development stages （meristem period, elongating period, cell wall thickening and end wall dissolving period and maturity period）, flowers, leaves, roots and underground stem. Results showed the expression of all the three miRNAs appeared dif- ferent at elongating period and cell wall thickening and end wall dissolving period, which were consistent with the results ofmiRNA chips, miR1450 expressed at highest level at maturity period and at lowest level at elongating period. miR156h was expressed higher in other tested tissues and organs than ramie fiber at four development stages. The expression of miR172b 1 was highest in meristem period fiber and was lowest level in flowers. In the present study, the method of analyzing expression ofmiRNA by stem-loop RT-PCR in ramie was established, which laid the foundation for the subsequent study about the function ofmiRNA on fiber growth and development in ramie.