Drought and high salinity are two major environmental factors that significantly limit the productivity of agricultural crops worldwide. WRKY transcription factors play essential roles in the adaptation of plants to abiotic stresses. However, WRKY genes involved in drought and salt tolerance in cotton (Gossypium hirsutum) are largely unknown. Here, a group IId WRKY gene, GhWRKY17, was isolated and characterized. GhWRKY17 was found to be induced after exposure to drought, salt, H2O2 and ABA. The constitutive expression of GhWRKY17 in Nicotiana benthamiana remarkably reduced plant tolerance to drought and salt stress, as determined through physiological analyses of the germination rate, root growth, survival rate, leaf water loss and Chl content. GhWRKY17 transgenic plants were observed to be more sensitive to ABA-mediated seed germination and root growth. However, overexpressing GhWRKY17 in N. benthamiana impaired ABA-induced stomatal closure. Furthermore, we found that GhWRKY17 modulated the increased sensitivity of plants to drought by reducing the level of ABA, and transcript levels of ABA-inducible genes, including AREB, DREB, NCED, ERD and LEA, were clearly repressed under drought and salt stress conditions. Consistent with the accumulation of reactive oxygen species (ROS), reduced proline contents and enzyme activities, elevated electrolyte leakage and malondialdehyde, and lower expression of ROS-scavenging genes, including APX, CAT and SOD, the GhWRKY17 transgenic plants exhibited reduced tolerance to oxidative stress compared with wild-type plants. These results therefore indicate that GhWRKY17 responds to drought and salt stress through ABA signaling and the regulation of cellular ROS production in plants.

BackgroundToxoplasmosis is an important zoonotic parasitic disease worldwide. In immune competent individuals, Toxoplasma gondii preferentially infects tissues of central nervous systems, which might be an adding factor of certain psychiatric disorders. Congenital transmission of T. gondii during pregnancy has been regarded as a risk factor for the health of newborn infants. While in immune-compromised individuals, the parasite can cause life-threatening infections. This study aims to investigate the prevalence of T. gondii infection among clinically healthy individuals and patients with psychiatric disorders in China and to identify the potential risk factors related to the vulnerability of infection in the population.MethodsSerum samples from 2634 healthy individuals and 547 patients with certain psychiatric disorders in Changchun and Daqing in the northeast, and in Shanghai in the south of China were examined respectively for the levels of anti-T. gondii IgG by indirect ELISA and a direct agglutination assay. Prevalence of T. gondii infection in the Chinese population in respect of gender, age, residence and health status was systematically analyzed.ResultsThe overall anti-T. gondii IgG prevalence in the study population was 12.3%. In the clinically healthy population 12.5% was sero-positive and in the group with psychiatric disorders 11.3% of these patients were positive with anti-T. gondii IgG. A significant difference (P = 0.004) was found between male and female in the healthy population, the seroprevalence was 10.5% in men versus 14.3% in women. Furthermore, the difference of T. gondii infection rate between male and female in the 20-19 year's group was more obvious, with 6.4% in male population and 14.6% in female population.ConclusionA significant higher prevalence of T. gondii infection was observed in female in the clinically healthy population. No correlation was found between T. gondii infection and psychiatric disorders in this study. Results suggest that women are more exposed to T. gondii infection than men in China. The data argue for deeper investigations for the potential risk factors that threat the female populations.

WRKY transcription factors constitute a very large family of proteins in plants and participate in modulating plant biological processes, such as growth, development and stress responses. However, the exact roles of WRKY proteins are unclear, particularly in non-model plants. In this study, Gossypium hirsutum WRKY41 (GhWRKY41) was isolated and transformed into Nicotiana benthamiana. Our results showed that overexpression of GhWRKY41 enhanced the drought and salt stress tolerance of transgenic Nicotiana benthamiana. The transgenic plants exhibited lower malondialdehyde content and higher antioxidant enzyme activity, and the expression of antioxidant genes was upregulated in transgenic plants exposed to osmotic stress. A β-glucuronidase (GUS) staining assay showed that GhWRKY41 was highly expressed in the stomata when plants were exposed to osmotic stress, and plants overexpressing GhWRKY41 exhibited enhanced stomatal closure when they were exposed to osmotic stress. Taken together, our findings demonstrate that GhWRKY41 may enhance plant tolerance to stress by functioning as a positive regulator of stoma closure and by regulating reactive oxygen species (ROS) scavenging and the expression of antioxidant genes.

WRKY transcription factor genes play significant roles in the response to biotic and abiotic stresses. Cotton (Gossypium hirsutum) is an important fiber and oil crop worldwide. We isolated and characterized GhWRKY39-1, which is a group IId WRKY gene that is present as a single copy in the cotton genome. Quantitative PCR analyses indicated that GhWRKY39-1 was induced by pathogen infection, defense-related signaling molecules, and abiotic stresses, such as NaCl and methyl viologen. An analysis of the subcellular localization of the GhWRKY39-1 protein indicated that it localized to the nucleus. Furthermore, constitutive overexpression of GhWRKY39-1 in Nicotiana benthamiana conferred a greater resistance to infection by both the bacterial pathogen Ralstonia solanacearum and the fungal pathogen Rhizoctonia solani. The transgenic plants also exhibited elevated mRNA levels of several pathogen-related (PR) genes, including PR1c, PR2 and PR4. Moreover, transgenic plants displayed an enhanced tolerance to salt and oxidative stress and elevated expression of several oxidation-related genes, including APX, CAT, GST and SOD. Overall, these results indicate that GhWRKY39-1 functions as a positive regulator of plant defense against pathogen infection and responses to salt stress and reactive oxygen species.

No abstract

No abstract

No abstract

Mitogen-activated protein kinase (MAPK) cascades play important roles in the perception of external signals and the generation of suitable responses. Cotton (Gossypium hirsutum) is an important fibre-producing and oil-producing crop worldwide. However, few MAPKs and their interaction partners have been functionally characterized in cotton. In the present study, the group A MAPK G. hirsutum (Gh)MPK6a was identified and characterized. GhMPK6a expression can be induced through multiple defence-related signal molecules and abiotic and biotic stresses. The ectopic expression of GhMPK6a in Nicotiana benthamiana reduced drought and salt tolerance, with elevated malondialdehyde content, higher reactive oxygen species content and lower abscisic acid content than in wild-type plants. Moreover, plants overexpressing GhMPK6a were sensitive to the bacterial pathogen Ralstonia solanacearum. Histochemical analysis of b-glucuronidase activity revealed that GhMPK6a showed tissue-specific expression during postgermination development, mixed bud differentiation, and pollination. Most importantly, GhMPK6a interacts with the upstream MAPK kinase GhMKK4, as shown by the use of yeast two-hybrid and bimolecular fluorescence complementation systems, compensating for a deficiency of MAPK interaction partners in cotton crops. Taken together, these results suggest that GhMPK6a negatively regulates osmotic stress and bacterial infection, and plays an important role in developmental processes. These results provide useful information for elucidating the roles of MAPK cascades in cotton crops. Structured digital abstractGhMPK6a physically interacts with GhMPK4 by two hybrid (View interaction) GhMPK6a and GhMPK4 physically interact by bimolecular fluorescence complementation (View interaction)