Transcriptome Analysis Reveals Genes Associated with Flooding Tolerance in Mulberry Plants.

Mulberry (Morus alba), a widely distributed economic plant, can withstand long-term flooding stress. However, the regulatory gene network underlying this tolerance is unknown. In the present study, mulberry plants were subjected to submergence stress. Subsequently, mulberry leaves were collected to perform quantitative reverse-transcription PCR (qRT-PCR) and transcriptome analysis. Genes encoding ascorbate peroxidase and glutathione S-transferase were significantly upregulated after submergence stress, indicating that they could protect the mulberry plant from flood damage by mediating ROS homeostasis. Genes that regulate starch and sucrose metabolism; genes encoding pyruvate kinase, alcohol dehydrogenase, and pyruvate decarboxylase (enzymes involved in glycolysis and ethanol fermentation); and genes encoding malate dehydrogenase and ATPase (enzymes involved in the TCA cycle) were also obviously upregulated. Hence, these genes likely played a key role in mitigating energy shortage during flooding stress. In addition, genes associated with ethylene, cytokinin, abscisic acid, and MAPK signaling; genes involved in phenylpropanoid biosynthesis; and transcription factor genes also showed upregulation under flooding stress in mulberry plants. These results provide further insights into the adaptation mechanisms and genetics of submergence tolerance in mulberry plants and could aid in the molecular breeding of these plants.

Toxicity evaluation of Wanzhou watershed of Yangtze Three Gorges Reservior in the flood season in Caenorhabditis elegans.

Three Gorges Reservoir (TGR) in the upper stream of Yangtze River in China is a reservoir with the largest and the longest yearly water-level drop. Considering the fact that most of safety assessments of water samples collected from TGR region were based on chemical analysis, we here employed Caenorhabditis elegans to perform in vivo safety assessment of original surface water samples collected from TGR region in the flood season in Wanzhou, Chongqing. Among the examined five original surface water samples, only exposure to original surface water sample collected from backwater area could induce the significant intestinal ROS production, enhance the intestinal permeability, and decrease the locomotion behavior. Additionally, exposure to original surface water sample collected from backwater area altered the expressions of sod-2, sod-5, clk-1, and mev-1. Moreover, mutation of sod-2 or sod-5 was susceptible to the potential toxicity of original surface water sample collected from backwater area on nematodes. Together, our results imply that exposure to surface water sample from the backwater area may at least cause the adverse effects on intestinal function and locomotion behavior in nematodes.

Author Correction: Toxicity evaluation of Wanzhou watershed of Yangtze Three Gorges Reservoir in the flood season in Caenorhabditis elegans.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

A MicroRNA-Mediated Insulin Signaling Pathway Regulates the Toxicity of Multi-Walled Carbon Nanotubes in Nematode Caenorhabditis elegans.

The underlying mechanisms for functions of microRNAs (miRNAs) in regulating toxicity of nanomaterials are largely unclear. Using Illumina HiSeq(TM) 2000 sequencing technique, we obtained the dysregulated mRNA profiling in multi-walled carbon nanotubes (MWCNTs) exposed nematodes. Some dysregulated genes encode insulin signaling pathway. Genetic experiments confirmed the functions of these dysregulated genes in regulating MWCNTs toxicity. In the insulin signaling pathway, DAF-2/insulin receptor regulated MWCNTs toxicity by suppressing function of DAF-16/FOXO transcription factor. Moreover, we raised a miRNAs-mRNAs network involved in the control of MWCNTs toxicity. In this network, mir-355 might regulate MWCNTs toxicity by inhibiting functions of its targeted gene of daf-2, suggesting that mir-355 may regulate functions of the entire insulin signaling pathway by acting as an upregulator of DAF-2, the initiator of insulin signaling pathway, in MWCNTs exposed nematodes. Our results provides highlight on understanding the crucial role of miRNAs in regulating toxicity of nanomaterials in organisms.

Molecular characteristics, recombinant expression and activity detection of OsGSTL1 from rice

The mRNA of OsGSTL1 was detected in the roots and leaves of rice plants at seedling and tillering stages, and their roots, leaves and panicles at the heading stage. The full-length open reading frame of OsGSTL1 cDNA was 732 bp and encoded a putative polypeptide of 243 amino acids with a calculated molecular mass of 27.30 kDa and a theoretical pI of 5.50. The protein sequences of OsGSTL1 exhibited typical feature of the lambda class GST, which contained the conserved domain "GST_C_Lambda" in C-terminal alpha helical domain and a highly conserved Cys42 in active center. In silico predictions showed that the OsGSTL1 protein was strongly hydrophilic. The phylogenetic analysis revealed OsGSTL1 belonged to monocots subgroup and was closer to IN2-1 of Z. may. The OsGSTL1 gene was cloned into pYTV vector and was introduced into yeast strain PEP4. Western blot analysis showed that the exogenous OsGSTL1 was expressed in the transformed yeast. The GST activity of the crude extracts of yeast showed that the OsGSTL1 transgenic yeast had higher levels of GST activities than the control yeasts. These findings suggested that the OsGSTL1 was a glutathione S-transferase and could play an important role during the growth and development processes in rice.