Active tectonics and strong earthquakes: A preface for the special issue

Active tectonics is not only the manifestation of the latest crustal activity but also the leading cause of strong earthquakes. With its complex active tectonic system, China has become an area with particularly severe seismic activity and related hazards worldwide. Therefore, a deep understanding of active tectonic characteristics and the occurrence patterns of strong earthquakes in China can help scientifically prevent or mitigate the risk of seismic disasters in urban planning and major engineering construction projects. In order to timely exchange the latest achievements in the field of active tectonics and strong earthquakes, this special issue on Active Tectonics and Strong Earthquakes selected 12 representative papers, mainly covering six different fields, including the earthquake-controlling process of active tectonics, paleoearthquakes, surveying and detection of active faults, seismic geological hazards, application of remote sensing technology and reservoir-induced earthquakes. Based on the new achievements of this issue and the research trends in related fields at home and abroad, it is suggested that future research on active tectonics and strong earthquakes should focus on four aspects: (1) comprehensive understanding of regional seismic hazards from the perspective of active tectonic evolution and active fault systems; (2) quantitative and refined field investigations of active tectonics; (3) application of high-precision remote sensing and various dating techniques continuously expanding the scope and timing of paleoearthquake research; (4) human-induced earthquakes

The Phosphatidylcholine Diacylglycerol Cholinephosphotransferase Is Required for Efficient Hydroxy Fatty Acid Accumulation in Transgenic Arabidopsis1[W][OA]

We previously identified an enzyme, phosphatidylcholine diacylglycerol cholinephosphotransferase (PDCT), that plays an important role in directing fatty acyl fluxes during triacylglycerol (TAG) biosynthesis. The PDCT mediates a symmetrical interconversion between phosphatidylcholine (PC) and diacylglycerol (DAG), thus enriching PC-modified fatty acids in the DAG pool prior to forming TAG. We show here that PDCT is required for the efficient metabolism of engineered hydroxy fatty acids in Arabidopsis (Arabidopsis thaliana) seeds. When a fatty acid hydroxylase (FAH12) from castor (Ricinus communis) was expressed in Arabidopsis seeds, the PDCT-deficient mutant accumulated only about half the amount of hydroxy fatty acids compared with that in the wild-type seeds. We also isolated a PDCT from castor encoded by the RcROD1 (Reduced Oleate Desaturation1) gene. Seed-specific coexpression of this enzyme significantly increased hydroxy fatty acid accumulation in wild type-FAH12 and in a previously produced transgenic Arabidopsis line coexpressing a castor diacylglycerol acyltransferase 2. Analyzing the TAG molecular species and regiochemistry, along with analysis of fatty acid composition in TAG and PC during seed development, indicate that PDCT acts in planta to enhance the fluxes of fatty acids through PC and enrich the hydroxy fatty acids in DAG, and thus in TAG. In addition, PDCT partially restores the oil content that is decreased in FAH12-expressing seeds. Our results add a new gene in the genetic toolbox for efficiently engineering unusual fatty acids in transgenic oilseeds

Overexpression of SOD2 Increases Salt Tolerance of Arabidopsis

The yeast (Schizosaccharomyces pombe) SOD2 (Sodium2) gene was introduced into Arabidopsis under the control of the cauliflower mosaic virus 35S promoter. Transformants were selected for their ability to grow on medium containing kanamycin. Southern- and northern-blot analyses confirmed that SOD2 was transferred into the Arabidopsis genome. There were no obvious morphological or developmental differences between the transgenic and wild-type (wt) plants. Several transgenic homozygous lines and wt plants (control) were evaluated for salt tolerance and gene expression. Overexpression of SOD2 in Arabidopsis improved seed germination and seedling salt tolerance. Analysis of Na(+) and K(+) contents of the symplast and apoplast in the parenchyma cells of the root cortex and mesophyll cells in the spongy tissue of the leaf showed that transgenic lines accumulated less Na(+) and more K(+) in the symplast than the wt plants did. The photosynthetic rate and the fresh weight of the transgenic lines were distinctly higher than that of wt plants after NaCl treatment. Results from different tests indicated that the expression of the SOD2 gene promoted a higher level of salt tolerance in vivo in transgenic Arabidopsis plants

Genome-wide identification and characterization of R2R3MYB family in Cucumis sativus.

BACKGROUND: The R2R3MYB proteins comprise one of the largest families of transcription factors in plants. Although genome-wide analysis of this family has been carried out in some species, little is known about R2R3MYB genes in cucumber (Cucumis sativus L.). PRINCIPAL FINDINGS: This study has identified 55 R2R3MYB genes in the latest cucumber genome and the CsR2R3MYB family contained the smallest number of identified genes compared to other species that have been studied due to the absence of recent gene duplication events. These results were also supported by genome distribution and gene duplication analysis. Phylogenetic analysis showed that they could be classified into 11 subgroups. The evolutionary relationships and the intron-exon organizations that showed similarities with Arabidopsis, Vitis and Glycine R2R3MYB proteins were also analyzed and suggested strong gene conservation but also the expansions of particular functional genes during the evolution of the plant species. In addition, we found that 8 out of 55 (∼14.54%) cucumber R2R3MYB genes underwent alternative splicing events, producing a variety of transcripts from a single gene, which illustrated the extremely high complexity of transcriptome regulation. Tissue-specific expression profiles showed that 50 cucumber R2R3MYB genes were expressed in at least one of the tissues and the other 5 genes showed very low expression in all tissues tested, which suggested that cucumber R2R3MYB genes took part in many cellular processes. The transcript abundance level analysis during abiotic conditions (NaCl, ABA and low temperature treatments) identified a group of R2R3MYB genes that responded to one or more treatments. CONCLUSIONS: This study has produced a comparative genomics analysis of the cucumber R2R3MYB gene family and has provided the first steps towards the selection of CsR2R3MYB genes for cloning and functional dissection that can be used in further studies to uncover their roles in cucumber growth and development

Genome-wide identification and characterization of R2R3MYB family in Cucumis sativus.

BACKGROUND: The R2R3MYB proteins comprise one of the largest families of transcription factors in plants. Although genome-wide analysis of this family has been carried out in some species, little is known about R2R3MYB genes in cucumber (Cucumis sativus L.). PRINCIPAL FINDINGS: This study has identified 55 R2R3MYB genes in the latest cucumber genome and the CsR2R3MYB family contained the smallest number of identified genes compared to other species that have been studied due to the absence of recent gene duplication events. These results were also supported by genome distribution and gene duplication analysis. Phylogenetic analysis showed that they could be classified into 11 subgroups. The evolutionary relationships and the intron-exon organizations that showed similarities with Arabidopsis, Vitis and Glycine R2R3MYB proteins were also analyzed and suggested strong gene conservation but also the expansions of particular functional genes during the evolution of the plant species. In addition, we found that 8 out of 55 (∼14.54%) cucumber R2R3MYB genes underwent alternative splicing events, producing a variety of transcripts from a single gene, which illustrated the extremely high complexity of transcriptome regulation. Tissue-specific expression profiles showed that 50 cucumber R2R3MYB genes were expressed in at least one of the tissues and the other 5 genes showed very low expression in all tissues tested, which suggested that cucumber R2R3MYB genes took part in many cellular processes. The transcript abundance level analysis during abiotic conditions (NaCl, ABA and low temperature treatments) identified a group of R2R3MYB genes that responded to one or more treatments. CONCLUSIONS: This study has produced a comparative genomics analysis of the cucumber R2R3MYB gene family and has provided the first steps towards the selection of CsR2R3MYB genes for cloning and functional dissection that can be used in further studies to uncover their roles in cucumber growth and development

QTL Mapping for Cucumber Fruit Size and Shape with Populations from Long and Round Fruited Inbred Lines

ABSTRACT: To gain insight into the molecular and genetic basis of fruit size and shape in cucumber, we conducted Quantitative Trait Locus (QTL) mapping with F2 and BC1F1 populations derived from a cross between the Northern-China type inbred line CNS21 and the Southern-China type inbred line RNS7. Populations were evaluated during two developmental stages, ovary at anthesis and commercial fruit (immature fruit). A total of 13 major-effect QTLs (R2 > 10%) were detected for six traits, and one of them, fruit shape index 2.1, explained more than 50% of phenotypic variation. All QTLs distributed on chromosome (chr) 1 and 2. We constructed a physical map containing almost all of the QTLs with their physical location from previous studies. For fruit size and shape, the highest number of QTLs were mapped on chr1 and chr6, and the fewest number were mapped on chr2 and chr7. At least one consensus region was presented on each chromosome. In addition, three candidate genes were predicted between the long-fruited and round-fruited inbred lines by comparing the sequences of the consensus region of chr3, where many QTLs for marketable fruit length had been detected. Our results provide a base for additional QTLs and molecular markers for fruit size and shape in cucumber breeding

Genome-Wide Identification and Characterization of WOX Genes in Cucumis sativus

WUSCHEL-related homeobox (WOX) proteins are plant-specific transcription factors that are profoundly involved in regulation of plant development and stress responses. In this study, we totally identified 11 WOX transcription factor family members in cucumber (Cucumis sativus, CsWOXs) genome and classified them into three clades with nine subclades based on phylogenetic analysis results. Alignment of amino acid sequences revealed that all WOX members in cucumber contained the typical homeodomain, which consists of 60-66 amino acids and is folded into a helix-turn-helix structure. Gene duplication event analysis indicated that CsWOX1a and CsWOX1b were a segment duplication pair, which might affect the number of WOX members in cucumber genome. The expression profiles of CsWOX genes in different tissues demonstrated that the members sorted into the ancient clade (CsWOX13a and CsWOX13b) were constitutively expressed at higher levels in comparison to the others. Cis-element analysis in promoter regions suggested that the expression of CsWOX genes was associated with phytohormone pathways and stress responses, which was further supported by RNA-seq data. Taken together, our results provide new insights into the evolution of cucumber WOX genes and improve our understanding about the biological functions of CsWOX family.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author