Overexpression of a 'Paulownia fortunei' MYB Factor Gene, PfMYB44, Increases Salt and Drought Tolerance in Arabidopsis thaliana.

Paulownia fortunei (Seem.) Hemsl is a Paulownia Sieb.et tree of the family Scrophulariaceae. It has become an important short-to-medium-term fast-growing multi-purpose tree species in China due to its rapid growth, strong adaptability, and excellent material properties. MYB transcription factors in plants have numerous and diverse functions, playing important roles in various aspects such as plant stress response. To investigate the function of MYB transcription factors in Paulownia fortunei, this study used PCR technology to clone the PfMYB44 gene from Paulownia fortunei. The homology of PfMYB44 and SiMYB44 (Sesamum indicum) was the highest. Expression analysis results showed that PfMYB44 was expressed in the root, stem, young leaf, and mature leaf of Paulownia fortunei, with the highest content in the root. Cold, drought, hot, salt, and ABA treatments could increase the expression level of PfMYB44. Overexpression-PfMYB44 plants were constructed, and physiological and molecular analysis showed that PfMYB44 could positively regulate salt and drought stresses. Under drought stress, the expression levels of AtP5CS, AtCAT1, AtNCED3 and AtSnRK2.4 in transgenic lines were significantly induced. Salt stress induced the expression of AtNHX1, AtSOS1, AtSOS2 and AtSOS3 genes, and the relative expression levels of these genes in transgenic Arabidopsis were higher. In conclusion, the functional study of PfMYB44 laid a certain foundation for the study of Paulownia stress resistance, and was helpful to the study of its stress resistance mechanism and the cultivation of new stress resistance varieties.

MxFRO4 confers iron and salt tolerance through up-regulating antioxidant capacity associated with the ROS scavenging.

Iron is involved in various metabolic pathways of plants. Stress from iron deficiency and toxicity in the soil adversely affects plant growth. Therefore, studying the mechanism of iron absorption and transport by plants is of important for resistance to iron stress and to increase crop yield. In this study, Malus xiaojinensis (a Fe-efficient Malus plant) was used as research material. A ferric reduction oxidase (FRO) family gene member was cloned and named MxFRO4. The MxFRO4 encoded a protein of 697 amino acid residues with a predicted molecular weight of 78.54 kDa and a theoretical isoelectric point of 4.90. A subcellular localization assay showed that the MxFRO4 protein was localized on the cell membrane. The expression of MxFRO4 was enriched in immature leaves and roots of M. xiaojinensis, and was strongly affected by low-iron, high-iron, and salt treatments. After introduction of MxFRO4 into Arabidopsis thaliana, the iron and salt stress tolerance of transgenic A. thaliana was greatly improved. Under exposure to low-iron and high-iron stresses, the primary root length, seedling fresh weight, contents of proline, chlorophyll, and iron, and iron(III) chelation activity of the transgenic lines were significantly increased compared with the wild type. The contents of chlorophyll and proline, and the activities of the antioxidant enzymes superoxide dismutase, peroxidase, and catalase were significantly higher in transgenic A. thaliana overexpressing MxFRO4 under salt stress compared with the wild type, whereas the malondialdehyde content was decreased. These results suggest that MxFRO4 contributes to alleviating the effects of low-iron, high-iron, and salinity stresses in transgenic A. thaliana.

Isolation and Functional Analysis of VvWRKY28, a Vitis vinifera WRKY Transcription Factor Gene, with Functions in Tolerance to Cold and Salt Stress in Transgenic Arabidopsis thaliana.

The grape (Vitis vinifera L.) not only has a long history of cultivation, but also has rich nutritional value and high economic value. However, grapes often face many threats in the growth process. For example, low temperature and salt stress restrict the growth status, yield, and geographical distribution of grapes. WRKY, as one of the largest transcription factor (TF) families in plants, participates in the response of plants to stress. VvWRKY28, a new zinc finger type transcriptional regulator gene, was isolated from Beichun (V. vinifera × V.amurensis) in this study. From the subcellular localization results, it can be concluded that VvWRKY28 was localized in the nucleus. The expression of VvWRKY28 was enriched in leaves (young and mature leaves), and cold and high salt conditions can induce high expression of VvWRKY28. After being transferred into Arabidopsis, VvWRKY28 greatly improved the tolerance of Arabidopsis to low temperature and high salt and also changed many physiological and biochemical indicators of transgenic Arabidopsis to cope with cold and high salt stimulation. The content of malondialdehyde (MDA) was decreased, but for chlorophyll and proline, their content increased, and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were improved. In addition, under cold stress, binding with cis-acting elements promotes the expression of downstream genes related to cold stress (RAB18, COR15A, ERD10, PIF4, COR47, and ICS1). Moreover, it also plays an active role in regulating the expression of genes related to salt stress (NCED3, SnRK2.4, CAT2, SOD1, SOS2, and P5CS1) under salt stress. Therefore, these results provide evidence that VvWRKY28 may play a role in the process of plant cold and salt stress tolerance.

Overexpression of a Malus baccata CBF transcription factor gene, MbCBF1, Increases cold and salinity tolerance in Arabidopsis thaliana.

CBFs play a crucial role when plants are in adverse environmental conditions for growth. However, there are few reports on the role of CBF gene in stress responses of Malus plant. In this experiment, a new CBF TF was separated from M. baccata which was named MbCBF1. MbCBF1 protein was found to be localized in the nucleus after subcellular localization. Furthermore, the expression of MbCBF1 was highly accumulated in new leaves and roots due to the high influence of cold and high salt in M. baccata seedlings. After introducing MbCBF1 into A. thaliana, transgenic A. thaliana can better adapt to the living conditions of cold and high salt. The increased expression of MbCBF1 in A. thaliana also increased the contents of proline, remarkablely improved the activities of SOD, POD and CAT, but the content of MDA was decreased. Although the chlorophyll content also decreased, it decreased less in transgenic plants. In short, above date showed that MbCBF1 has a positive effect on improving A. thaliana cold and high salt tolerance. MbCBF1 can regulate the expression of its downstream gene in transgenic lines, up-regulate the expression of key genes COR15a, RD29a/bandCOR6.6/47 related to low temperature under cold conditions and NCED3, CAT1, P5CS1, RD22, DREB2A,PIF1/4, SOS1 and SnRK2.4 related to salt stress under high salt conditions, so as to further improve the adaptability and tolerance of the transgenic plants to low temperature and high salt environment.

A two-step DNA barcoding approach for delimiting moth species: moths of Dongling Mountain (Beijing, China) as a case study.

DNA barcoding, based on a fragment of cytochrome c oxidase I (COI) mtDNA, is as an effective molecular tool for identification, discovery, and biodiversity assessment for most animals. However, multiple gene markers coupled with more sophisticated analytical approaches may be necessary to clarify species boundaries in cases of cryptic diversity or morphological plasticity. Using 339 moths collected from mountains surrounding Beijing, China, we tested a pipeline consisting of two steps: (1) rapid morphospecies sorting and screening of the investigated fauna with standard COI barcoding approaches; (2) additional analyses with multiple molecular markers for those specimens whose morphospecies and COI barcode grouping were incongruent. In step 1, 124 morphospecies were delimited into 116 barcode units, with 90% of the conflicts being associated with specimens identified to the genus Hypena. In step 2, 55 individuals representing all 12 Hypena morphospecies were analysed using COI, COII, 28S, EF-1a, Wgl sequences or their combinations with the BPP (Bayesian Phylogenetics and Phylogeography) multigene species delimitation method. The multigene analyses supported the delimitation of 5 species, consistent with the COI analysis. We conclude that a two-step barcoding analysis pipeline is able to rapidly characterize insect biodiversity and help to elucidate species boundaries for taxonomic complexes without jeopardizing overall project efficiency by substantially increasing analytical costs.