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Comparative Analysis and Identification of miRNAs and Their Target Genes Responsive to Salt Stress in Diploid and Tetraploid Paulownia fortunei Seedlings.

Fan G, Li X, Deng M, Zhao Z, Yang L - PLoS ONE (2016)

Bottom Line: The results indicated that salt stress had different physiological effects on diploid and tetraploid P. fortunei.Comparing their expression levels in diploid and tetraploid P. fortunei, we found 10 conserved and 10 novel miRNAs that were significantly differentially expressed under salt treatment, among them eight were identified as miRNAs probably associated with higher salt tolerance in tetraploid P. fortunei than in diploid P. fortunei.The results provided information at the physiological and molecular levels for further research into the response mechanisms of P. fortunei to salt stress.

View Article: PubMed Central - PubMed

Affiliation: Institute of Paulownia, Henan Agricultural University, 450002 Zhengzhou, Henan, P.R. China.

ABSTRACT
Salt stress is a global environmental problem that affects plant growth and development. Paulownia fortunei is an adaptable and fast-growing deciduous tree native to China that is environmentally and economically important. MicroRNAs (miRNAs) play important regulatory roles in growth, development, and stress responses in plants. MiRNAs that respond to biotic stresses have been identified; however, how miRNAs in P. fortunei respond to salt stress has not yet been reported. To identify salt-stress-responsive miRNAs and predict their target genes, four small RNA and four degradome libraries were constructed from NaCl-treated and NaCl-free leaves of P. fortunei seedlings. The results indicated that salt stress had different physiological effects on diploid and tetraploid P. fortunei. We detected 53 conserved miRNAs belonging to 17 miRNA families and 134 novel miRNAs in P. fortunei. Comparing their expression levels in diploid and tetraploid P. fortunei, we found 10 conserved and 10 novel miRNAs that were significantly differentially expressed under salt treatment, among them eight were identified as miRNAs probably associated with higher salt tolerance in tetraploid P. fortunei than in diploid P. fortunei. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed to predict the functions of the target genes of the conserved and novel miRNAs. The expressions of 10 differentially expressed miRNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR). This is the first report on P. fortunei miRNAs and their target genes under salt stress. The results provided information at the physiological and molecular levels for further research into the response mechanisms of P. fortunei to salt stress.

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Determination of physiological indices.PF2:diploid P. fortunei; PF4: tetraploid P. fortunei. Standard error of the mean for three technical replicates is represented by the error bars.
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pone.0149617.g001: Determination of physiological indices.PF2:diploid P. fortunei; PF4: tetraploid P. fortunei. Standard error of the mean for three technical replicates is represented by the error bars.

Mentions: The relative water contents of the leaves of diploid and tetraploid P. fortunei declined progressively from 85.23% to 74.65% and from 87.23% to 74.65%, respectively, in the 0%, 0.2%, 0.4%, and 0.6% salt-treated plants (Fig 1). At the same salinity, the relative water content in tetraploid was higher than that in diploid. The chlorophyll contents of the leaves followed the same trend as the relative water contents; that is, with increasing salt concentrations, the chlorophyll content of the leaves declined progressively from 3.15mg·g−1 to 2.61mg·g−1 and from 3.19mg·g−1 to 2.73mg·g−1in diploid and tetraploid P. fortunei, respectively. At the same salinity, tetraploid contained higher chlorophyll content than diploid (Fig 1). The contents of relative conductivity and MDA in leaves generally increased with increasing salt concentrations. Relative conductivity increased progressively from 21.29% to 49.23% and from 18.23% to 44.12%in diploid and tetraploid, respectively; and MDA content of leaves increased progressively from 4.23μmol·g−1 to 7.23μmol·g−1andfrom 4.21μmol·g−1 to 7.11μmol·g−1in diploid and tetraploid, respectively (Fig 1). The soluble sugar content in leaves increased progressively from 0.33mg·g−1 to 0.61mg·g−1and from 0.35mg·g−1 to 0.69mg·g−1in diploid and tetraploid, respectively. The proline content of leaves increased progressively from 69.8μg·g−1 to 99.7μg·g−1and from 75.9μg·g−1 to 105.3μg·g−1in diploid and tetraploid, respectively (Fig 1). At the same salinity, the relative conductivity and MDA content of leaves in diploid plants were always higher than in tetraploid plants, while the contents of soluble sugar and proline in leaves were always higher in tetraploid compared with diploid.


Comparative Analysis and Identification of miRNAs and Their Target Genes Responsive to Salt Stress in Diploid and Tetraploid Paulownia fortunei Seedlings.

Fan G, Li X, Deng M, Zhao Z, Yang L - PLoS ONE (2016)

Determination of physiological indices.PF2:diploid P. fortunei; PF4: tetraploid P. fortunei. Standard error of the mean for three technical replicates is represented by the error bars.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764520&req=5

pone.0149617.g001: Determination of physiological indices.PF2:diploid P. fortunei; PF4: tetraploid P. fortunei. Standard error of the mean for three technical replicates is represented by the error bars.
Mentions: The relative water contents of the leaves of diploid and tetraploid P. fortunei declined progressively from 85.23% to 74.65% and from 87.23% to 74.65%, respectively, in the 0%, 0.2%, 0.4%, and 0.6% salt-treated plants (Fig 1). At the same salinity, the relative water content in tetraploid was higher than that in diploid. The chlorophyll contents of the leaves followed the same trend as the relative water contents; that is, with increasing salt concentrations, the chlorophyll content of the leaves declined progressively from 3.15mg·g−1 to 2.61mg·g−1 and from 3.19mg·g−1 to 2.73mg·g−1in diploid and tetraploid P. fortunei, respectively. At the same salinity, tetraploid contained higher chlorophyll content than diploid (Fig 1). The contents of relative conductivity and MDA in leaves generally increased with increasing salt concentrations. Relative conductivity increased progressively from 21.29% to 49.23% and from 18.23% to 44.12%in diploid and tetraploid, respectively; and MDA content of leaves increased progressively from 4.23μmol·g−1 to 7.23μmol·g−1andfrom 4.21μmol·g−1 to 7.11μmol·g−1in diploid and tetraploid, respectively (Fig 1). The soluble sugar content in leaves increased progressively from 0.33mg·g−1 to 0.61mg·g−1and from 0.35mg·g−1 to 0.69mg·g−1in diploid and tetraploid, respectively. The proline content of leaves increased progressively from 69.8μg·g−1 to 99.7μg·g−1and from 75.9μg·g−1 to 105.3μg·g−1in diploid and tetraploid, respectively (Fig 1). At the same salinity, the relative conductivity and MDA content of leaves in diploid plants were always higher than in tetraploid plants, while the contents of soluble sugar and proline in leaves were always higher in tetraploid compared with diploid.

Bottom Line: The results indicated that salt stress had different physiological effects on diploid and tetraploid P. fortunei.Comparing their expression levels in diploid and tetraploid P. fortunei, we found 10 conserved and 10 novel miRNAs that were significantly differentially expressed under salt treatment, among them eight were identified as miRNAs probably associated with higher salt tolerance in tetraploid P. fortunei than in diploid P. fortunei.The results provided information at the physiological and molecular levels for further research into the response mechanisms of P. fortunei to salt stress.

View Article: PubMed Central - PubMed

Affiliation: Institute of Paulownia, Henan Agricultural University, 450002 Zhengzhou, Henan, P.R. China.

ABSTRACT
Salt stress is a global environmental problem that affects plant growth and development. Paulownia fortunei is an adaptable and fast-growing deciduous tree native to China that is environmentally and economically important. MicroRNAs (miRNAs) play important regulatory roles in growth, development, and stress responses in plants. MiRNAs that respond to biotic stresses have been identified; however, how miRNAs in P. fortunei respond to salt stress has not yet been reported. To identify salt-stress-responsive miRNAs and predict their target genes, four small RNA and four degradome libraries were constructed from NaCl-treated and NaCl-free leaves of P. fortunei seedlings. The results indicated that salt stress had different physiological effects on diploid and tetraploid P. fortunei. We detected 53 conserved miRNAs belonging to 17 miRNA families and 134 novel miRNAs in P. fortunei. Comparing their expression levels in diploid and tetraploid P. fortunei, we found 10 conserved and 10 novel miRNAs that were significantly differentially expressed under salt treatment, among them eight were identified as miRNAs probably associated with higher salt tolerance in tetraploid P. fortunei than in diploid P. fortunei. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed to predict the functions of the target genes of the conserved and novel miRNAs. The expressions of 10 differentially expressed miRNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR). This is the first report on P. fortunei miRNAs and their target genes under salt stress. The results provided information at the physiological and molecular levels for further research into the response mechanisms of P. fortunei to salt stress.

Show MeSH