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author:("Bo, wenshan")
1.  Cloning of the Cryptochrome-Encoding PeCRY1 Gene from Populus euphratica and Functional Analysis in Arabidopsis 
PLoS ONE  2014;9(12):e115201.
Cryptochromes are photolyase-like blue/UV-A light receptors that evolved from photolyases. In plants, cryptochromes regulate various aspects of plant growth and development. Despite of their involvement in the control of important plant traits, however, most studies on cryptochromes have focused on lower plants and herbaceous crops, and no data on cryptochrome function are available for forest trees. In this study, we isolated a cryptochrome gene, PeCRY1, from Euphrates poplar (Populus euphratica), and analyzed its structure and function in detail. The deduced PeCRY1 amino acid sequence contained a conserved N-terminal photolyase-homologous region (PHR) domain as well as a C-terminal DQXVP-acidic-STAES (DAS) domain. Secondary and tertiary structure analysis showed that PeCRY1 shares high similarity with AtCRY1 from Arabidopsis thaliana. PeCRY1 expression was upregulated at the mRNA level by light. Using heterologous expression in Arabidopsis, we showed that PeCRY1 overexpression rescued the cry1 mutant phenotype. In addition, PeCRY1 overexpression inhibited hypocotyl elongation, promoted root growth, and enhanced anthocyanin accumulation in wild-type background seedlings grown under blue light. Furthermore, we examined the interaction between PeCRY1 and AtCOP1 using a bimolecular fluorescence complementation (BiFc) assay. Our data provide evidence for the involvement of PeCRY1 in the control of photomorphogenesis in poplar.
PMCID: PMC4264880  PMID: 25503486
2.  Genome-wide analysis of salt-responsive and novel microRNAs in Populus euphratica by deep sequencing 
BMC Genetics  2014;15(Suppl 1):S6.
Populus euphratica is a representative model woody plant species for studying resistance to abiotic stresses such as drought and salt. Salt stress is one of the most common environmental factors that affect plant growth and development. MicroRNAs (miRNAs) are small, noncoding RNAs that have important regulatory functions in plant growth, development, and response to abiotic stress.
To investigate the miRNAs involved in the salt-stress response, we constructed four small cDNA libraries from P. euphratica plantlets treated with or without salt (300 mM NaCl, 3 days) in either the root or leaf. Using high-throughput sequencing to identify miRNAs, we found 164 conserved miRNAs belonging to 44 families. Of these, 136 novel miRNAs were from the leaf, and 128 novel miRNAs were from the root. In response to salt stress, 95 miRNAs belonging to 46 conserved miRNAs families changed significantly, with 56 miRNAs upregulated and 39 miRNAs downregulated in the leaf. A comparison of the leaf and root tissues revealed 155 miRNAs belonging to 63 families with significantly altered expression, including 84 upregulated and 71 downregulated miRNAs. Furthermore, 479 target genes in the root and 541 targets of novel miRNAs in the leaf were predicted, and functional information was annotated using the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases.
This study provides a novel visual field for understanding the regulatory roles of miRNAs in response to salt stress in Populus.
PMCID: PMC4118626  PMID: 25079824
High-throughput sequencing; microRNA; Populus euphratica; Salt stress
3.  Genetic diversity and population structure of the Tibetan poplar (Populus szechuanica var. tibetica) along an altitude gradient 
BMC Genetics  2014;15(Suppl 1):S11.
The Tibetan poplar (Populus szechuanica var. tibetica Schneid), which is distributed at altitudes of 2,000-4,500 m above sea level, is an ecologically important species of the Qinghai-Tibet Plateau and adjacent areas. However, the genetic adaptations responsible for its ability to cope with the harsh environment remain unknown.
In this study, a total of 24 expressed sequence tag microsatellite (EST-SSR) markers were used to evaluate the genetic diversity and population structure of Tibetan poplars along an altitude gradient. The 172 individuals were of genotypes from low-, medium- and high-altitude populations, and 126 alleles were identified. The expected heterozygosity (HE) value ranged from 0.475 to 0.488 with the highest value found in low-altitude populations and the lowest in high-altitude populations. Genetic variation was low among populations, indicating a limited influence of altitude on microsatellite variation. Low genetic differentiation and high levels of gene flow were detected both between and within the populations along the altitude gradient. An analysis of molecular variance (AMOVA) showed that 6.38% of the total molecular variance was attributed to diversity between populations, while 93.62% variance was associated with differences within populations. There was no clear correlation between genetic variation and altitude, and a Mantel test between genetic distance and altitude resulted in a coefficient of association of r = 0.001, indicating virtually no correlation.
Microsatellite genotyping results showing genetic diversity and low differentiation suggest that extensive gene flow may have counteracted local adaptations imposed by differences in altitude. The genetic analyses carried out in this study provide new insight for conservation and optimization of future arboriculture.
PMCID: PMC4118629  PMID: 25079034
Gene flow; Microsatellite; Genetic diversity; Qinghai-Tibet plateau; Populus szechuanica var. tibetica.
4.  Transcriptional profiling by cDNA-AFLP analysis showed differential transcript abundance in response to water stress in Populus hopeiensis 
BMC Genomics  2012;13:286.
Drought is one of the main environmental factors limiting tree growth and productivity of plantation forests worldwide. Populus hopeiensis Hu et Chow is one of the most important commercial plantation tree species in China. However, the genes controlling drought tolerance in this species have not been identified or characterized. Here, we conducted differential expression analyses and identified a number of genes that were up- or downregulated in P. hopeiensis during water stress. To the best of our knowledge, this is the first comprehensive study of differentially expressed genes in water-stressed P. hopeiensis.
Using the cDNA-AFLP detection technique, we used 256 primer combinations to identify differentially expressed genes in P. hopeiensis during water stress. In total, 415 transcript derived-fragments (TDFs) were obtained from 10× deep sequencing of 473 selected TDFs. Of the 415 TDFs, 412 were annotated by BLAST searches against various databases. The majority of these genes encoded products involved in ion transport and compartmentalization, cell division, metabolism, and protein synthesis. The TDFs were clustered into 12 groups on the basis of their expression patterns. Of the 415 reliable TDFs, the sequences of 35 were homologous to genes that play roles in short or long-term resistance to drought stress. Some genes were further selected for validation of cDNA-AFLP expression patterns using real-time PCR analyses. The results confirmed the expression patterns that were detected using the cDNA-AFLP technique.
The cDNA-AFLP technique is an effective and powerful tool for identifying candidate genes that are differentially expressed under water stress. We demonstrated that 415 TDFs were differentially expressed in water-stressed poplar. The products of these genes are involved in various biological processes in the drought response of poplar. The results of this study will aid in the identification of candidate genes of future experiments aimed at understanding this response of poplar.
PMCID: PMC3443059  PMID: 22747754

Results 1-4 (4)