Functional and Expressional quantitation of Selected MicroRnAs in Response to Low Temperature and NaCI Stress Conditions in and Root Tissues of Arabldopsis Thallana
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Date
2013
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UAS, Dharwad
Abstract
The discovery of miRNAs has led to a fundamental change in the understanding of
complex biological mechanisms involved in plant responses to stress tolerance. In this study,
the expression of seven selected miRNAs was studied in Arabidopsis thaliana plants
experiencing low temperature and salt stress separately. The selected miRNAs were in situ
hybridized with Locked Nucleic Acid (LNA)-modified oligonucleotide probes. Among the
tested miRNAs, expression of miR161, miR168, miR171 and miR397a in leaf tissues and
miR171 and miR397a in root tissues was recorded in control plants. Elevated expression of
miR171 and miR397a was recorded in both tissue types of low temperature treated plants. A
set of four miRNAs viz., miR171, miR395b, miR399e and miR399 showed their up
regulation in both tissue types upon NaCl (300 mM) treatment. Expression of miR168 was
recorded only in leaf tissues, and on the other hand, down regulation of miR397a was
recorded in both tissue types in response to NaCl stress. The miRNA stem-loop RT-PCR
assay indicated gradual increase in the expression of miR171 and miR397 with the highest of
4.28 and 3.49 fold changes in leaf tissues of A. thaliana plants experiencing low temperature
stress and 6.5 and 6.3 fold up-regulation of miR171, 0.8 and 0.9 fold down-regulation of
miR397a and 3.4-3.5 fold up-regulation of miR399 and miR399e in leaf and root tissues,
respectively, at 24 hrs of exposure to salt stress. The RT-qPCR assay recorded reduced levels
of miRNA target gene transcripts viz., SCL6 III, SCL6 IV, LAC2, and LAC17 in response to
low temperature and SCL6 III, SCL6 IV, APS1, APS4 and AGO1 transcripts in response NaCl
treatment in both tissue types of Arabidopsis thaliana plants. The study points at the
possibility of modulating low temperature and salt tolerance in plants through the down
regulation of specific cognate genes.