Volume 15, No 5, May 2005
ISSN: 1001-0602
EISSN: 1748-7838 2018
impact factor 17.848*
(Clarivate Analytics, 2019)
Volume 15 Issue 5, May 2005: 336-360
ORIGINAL ARTICLES
Identification and characterization of new plant microRNAs using EST analysis
Bao Hong ZHANG1, 2, *, Xiao Ping PAN1, Qing Lian WANG2, George P. COBB1, Todd A. ANDERSON1
1The Institute of Environmental and Human Health (TIEHH), and Department of Environmental Toxicology, Texas Tech University, Lubbock, TX 79409-1163, USA
2 Henan Institute of Science and Technology, Xinxiang 453003, China
Correspondence: Bao Hong ZHANG(baohong.zhang@ttu.edu)
Seventy-five previously known plant microRNAs (miRNAs) were classified into 14 families according to their gene sequence identity. A total of 18,694 plant expressed sequence tags (EST) were found in the GenBank EST databases by comparing all previously known Arabidopsis miRNAs to GenBank's plant EST databases with BLAST algorithms. After removing the EST sequences with high numbers (more than 2) of mismatched nucleotides, a total of 812 EST contigs were identified. After predicting and scoring the RNA secondary structure of the 812 EST sequences using mFold software, 338 new potential miRNAs were identified in 60 plant species. miRNAs are widespread. Some microRNAs may highly conserve in the plant kingdom, and they may have the same ancestor in very early evolution. There is no nucleotide substitution in most miRNAs among many plant species. Some of the new identified potential miRNAs may be induced and regulated by environmental biotic and abiotic stresses. Some may be preferentially expressed in specific tissues, and are regulated by developmental switching. These findings suggest that EST analysis is a good alternative strategy for identifying new miRNA candidates, their targets, and other genes. A large number of miRNAs exist in different plant species and play important roles in plant developmental switching and plant responses to environmental abiotic and biotic stresses as well as signal transduction. Environmental stresses and developmental switching may be the signals for synthesis and regulation of miRNAs in plants. A model for miRNA induction and expression, and gene regulation by miRNA is hypothesized.
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