Analysis Of Differential Expression Of Cold-tolerance Related MicroRNA In Cassava

MicroRNA(miRNA) is a class of-22nt non-coding RNAs that can play important regulatory roles in plants by targeting mRNAs for cleavage or translational repression. microRNAs are key regulators of nearly all essential biological processes, including development, cell proliferation and apoptosis and stress responses. Manihot esculenta Crantz is one typical tropical crop, the research about cold stress is the most important program for cold mechanism research and genetic improvement.In the present study, we used qRT-PCR (quantitative Real Time-PCR) to validate the different expression of 23 miRNA in cassava C4 and KU50 between normal development and cold stress. Besides, a new approach was used to make computational prediction of target mRNAs. The main results were summarized as follows:1. This present study completely constructed the biological process that cassava responed to cold stress. Besides, we gorped the sampling metheds and cold stress times for miRNA expression analysis. It provided material basis for cold mechanism research of Cassava Program 973.2. Compared with U6 gene 20 of the 23 cold candidate miRNAs were highly expressed under normal condition. The result indidated these miRNAs had different expression in cassava leaf and root.3. A total of 15 miRNAs highly expressed under AT cold stress, including 6 up-regulated: miR156a,399e,1045125,4367213,1717290,6915202, and 10 down-regulated:166a,171a, b, 157b,390b,166b, c, d, e,6915202. They were the important target miRNAs for study cassava cold mechanism research and genes resource. Besides, there were 9 up-regulated miRNAs and 6 down-regulated miRNAs under AH cold stress as well as 6 up-regulated and 6 down-regulated miRNAs under NAH, indicated that they regulated different cold mechanism in cassava.4. This study analyzed thoroughly about expression patterns in two cassava varieties under different treatments, revealed that 20/23 miRNA had different expression patterns in cassava C4 as well as 17/23 in KU50 under AT cold stress,19/23 miRNA had different patterns in C4 as well as 17/23 in KU50 under AH and 17/23 miRNA in C4 as well as 17/23 in KU50 under NAH cold stress. The results indicated that there were some different cold-tolerance related genes targeted by these microRNAs.5. Hitsensor software was used to predict miRNA targets, and got 180 miRNA:target binding pairs. The mRNA targets of 15 miRNAs expressed under AT cold stress belonged to different types and had different function in plant. This study collected more related cold-resistance miRNAs and their targets. It provided a lot of important information for cassava cold mechanism research and genetic improvement.