| Tomato is an important horticultural crop, not only has high economic value, but also occupies a pivotal position in life sciences research. Low potassium is one of the main factors limiting tomato growth and development, yield and quality. The untilization of different genotypes of low potassium tolerance tomato is studied. It is an effective way to relieve the contradiction of potassium defienciency and plant needs. So the response mechanism of low potassium on tomato has been researched to screen potassium-tolerance materials and develop new varieties of tomato. In addition, it has important theoretical and practical significance. MiRNA is endogenous small RNA (sRNAs) molecule having a class size of 18 to 25 nucleotides which involved in the growth and development, the physiological processes and the stress regulation of the organism, but has yet to see the regulation about microRNA regulation of plant potassium Stress. In this paper, two kinds of different tolerance large fruit tomato (potassium-sensitive and potassium-tolerance tomato 081018 and 081034 tomato) were used as materials, treated with low potassium at the time of tomato seedlings with three-leaf, taken root, stem and leaf at 0 hours,12 hours,24 and 72 hours, extracted total RNA with Trizol, quantitated libraries with the use of Pico green fluorescence spectrophotometer, sequenced and analyzed microRNA with the Agilent 2100. According to test results conduct the bioinformatics analysis to identify significant differences of small RNA in the expression. RT-PCR was carried out to verify their gene expression, and further prediction analysis and functional studies on target gene to clarify the mechanism of miRNA response low potassium stress in different tolerance of tomato. Above research results are expected to provide new research ideas and means to further improve plant resistance in the breeding level. The main results obtained are as follows:Compore Unique Sequences with non-coding RNA sequences in database Rfam (11.0) using Blast program to obtain the corresponding miRNA annotation. Known and newly discovered miRNA were compared with miRBase database, the results showed that:in tomato of the No.18 and No.34 has identified the same known miRNA with 229,189 and 171, respectively in and tomato, tobacco and potato. Another 86 new miRNA expression appears. Comparing these miRNA expression patterns in the two tomato strains after low potassium treatment,24 up-regulated and 28 down-regulated expression of the miRNA were found in 18 strains above ground, and up-regulated and 22 down-regulated expression of the miRNA were selected in 34 strains above ground. In comparison with the aerial parts, five up-regulated and seven down-regulated expression of the miRNA were both in the two strains of tomato after treatments with low potassium, while the different and opposite expression miRNA in the two lines on the ground part were four and underground were found five. Verified nine differentially expressed microRNA and its target gene expression with gRT-PCR analysis, correlation analysis showed miR168a differential expression clearly after low potassium treatment in the two strains of tomato and significantly correlated compared with its target genes AGO1 expression. Our results suggest that miR168 may play an important regulatory role in responsing in different tolerance tomato under Potassium stress. |
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