Overexpression of an aquaglyceroporin gene from Trichoderma harzianum improves water-use efficiency and drought tolerance in Nicotiana tabacum.

Aquaporins (AQPs) and aquaglyceroporins (AQGPs) are integral membrane proteins that mediate the transport of water and solutes, such as glycerol and urea, across membranes. AQP and AQGP genes represent a valuable tool for biotechnological improvement of plant tolerance to environmental stresses. We previously isolated a gene encoding for an aquaglyceroporin (ThAQGP), which was up-regulated in Trichoderma harzianum during interaction with the plant pathogen Fusarium solani. This gene was introduced into Nicotiana tabacum and plants were physiologically characterized. Under favorable growth conditions, transgenic progenies did not had differences in both germination and growth rates when compared to wild type. However, physiological responses under drought stress revealed that transgenic plants presented significantly higher transpiration rate, stomatal conductance, photosynthetic efficiency and faster turgor recovery than wild type. Quantitative RT-PCR analysis demonstrated the presence of ThAQGP transcripts in transgenic lines, showing the cause-effect relationship between the observed phenotype and the expression of the transgene. Our results underscore the high potential of T. harzianum as a source of genes with promising applications in transgenic plants tolerant to drought stress.

Identification of differentially expressed genes from Trichoderma harzianum during growth on cell wall of Fusarium solani as a tool for biotechnological application.

BACKGROUND: The species of T. harzianum are well known for their biocontrol activity against many plant pathogens. However, there is a lack of studies concerning its use as a biological control agent against F. solani, a pathogen involved in several crop diseases. In this study, we have used subtractive library hybridization (SSH) and quantitative real-time PCR (RT-qPCR) techniques in order to explore changes in T. harzianum genes expression during growth on cell wall of F. solani (FSCW) or glucose. RT-qPCR was also used to examine the regulation of 18 genes, potentially involved in biocontrol, during confrontation between T. harzianum and F. solani. RESULTS: Data obtained from two subtractive libraries were compared after annotation using the Blast2GO suite. A total of 417 and 78 readable EST sequence were annotated in the FSCW and glucose libraries, respectively. Functional annotation of these genes identified diverse biological processes and molecular functions required during T. harzianum growth on FSCW or glucose. We identified various genes of biotechnological value encoding to proteins which function such as transporters, hydrolytic activity, adherence, appressorium development and pathogenesis. Fifteen genes were up-regulated and sixteen were down-regulated at least at one-time point during growth of T. harzianum in FSCW. During the confrontation assay most of the genes were up-regulated, mainly after contact, when the interaction has been established. CONCLUSIONS: This study demonstrates that T. harzianum expressed different genes when grown on FSCW compared to glucose. It provides insights into the mechanisms of gene expression involved in mycoparasitism of T. harzianum against F. solani. The identification and evaluation of these genes may contribute to the development of an efficient biological control agent.

Detection of genotoxic, cytotoxic, and protective activities of Eugenia dysenterica DC. (Myrtaceae) in mice.

Eugenia dysenterica DC. (Myrtaceae), popularly known in Brazil as cagaiteira, is a widespread plant species in the Brazilian Cerrado. In folk medicine, the leaves of this plant are used to treat diarrhea and dysentery. The fruits are used for fresh consumption and industrial purposes. Because of the use of this plant as a therapeutic resource and food, the present study evaluated the genotoxic, cytotoxic, antigenotoxic, and anticytotoxic effects of the lyophilized ethanolic leaf extract of E. dysenterica using the mouse bone marrow micronucleus test. The genotoxicity and antigenotoxicity of this extract were evaluated using the frequency of micronucleated polychromatic erythrocytes, and the cytotoxicity and anticytotoxicity were assessed by the polychromatic and normochromatic erythrocyte ratio. According to our results, the lyophilized ethanolic leaf extract of E. dysenterica exhibited genotoxic and cytotoxic effects at the higher doses and protection against cyclophosphamide-induced genotoxic and cytotoxic actions at all doses tested.

Assessment of the genotoxic, antigenotoxic, and cytotoxic activities of the ethanolic fruit extract of Solanum lycocarpum A. St. Hill. (Solanaceae) by micronucleus test in mice.

Solanum lycocarpum A. St. Hill. (Family Solanaceae), popularly known in Brazil as lobeira, is a common weed in the Brazilian Cerrado vegetation. The fruits of this species have been used in Brazil for culinary purposes and in folk medicine as a sedative, diuretic, antiepileptic, antispasmodic, hypoglycemic, and hypocholesterolemic agent as well as in the control of obesity. Due to the spreading use of this plant as a therapeutic resource and food, the present study aimed to evaluate the genotoxic, antigenotoxic, and cytotoxic effects of S. lycocarpum ethanolic fruit extract using the mouse bone marrow micronucleus test. Both genotoxicity and antigenotoxicity of this ethanolic fruit extract were evaluated by using the frequency of micronucleated polychromatic erythrocytes, whereas cytotoxicity was assessed by the polychromatic and normochromatic erythrocytes ratio. Our results indicated that although S. lycocarpum ethanolic fruit extract did not exhibit genotoxic effect in mice bone marrow, both cytotoxic and antigenotoxic actions were evidenced at all tested doses.

Solanum paniculatum L. leaf and fruit extracts: assessment of modulation of cytotoxicity and genotoxicity by micronucleus test in mice.

Solanum paniculatum L. is a plant species widespread throughout tropical America, especially in the Brazilian Savanna region. It is used in Brazil for culinary purposes and in folk medicine to treat liver and gastric dysfunctions, as well as hangovers. Previous studies with S. paniculatum ethanolic leaf extract (ELE) or ethanolic fruit extract (EFE) demonstrated that they have no genotoxic activity meant either in the micronucleus test in mice or in the phage induction SOS Inductest in bacterial strains; however, cytotoxicity was demonstrated in both tests. Because of the spread use of this plant as a therapeutic resource and food, the present study aimed at evaluating the modulator effects of S. paniculatum ELE or EFE against mitomycin C (MMC) using the mouse bone marrow micronucleus test. This short-term test was used to detect the acute effects of responsive erythropoiesis after 24- and 48-hour exposure periods. Swiss-Webster mice were orally treated with three different concentrations (100, 200, or 300 mg/kg) of ELE or EFE simultaneously with a single dose of MMC (4 mg/kg i.p.). Antigenotoxicity was evaluated using the frequency of micronucleated polychromatic erythrocytes (MNPCEs), whereas anticytotoxicity was assessed by the polychromatic/normochromatic erythrocyte ratio. Our results demonstrated that neither the ELE nor EFE of S. paniculatum protected cells against the cytotoxic action of MMC. Nevertheless, the present study showed the antimutagenic effect of ELE after a 24-hour treatment (reduction in the frequencies of MNPCEs after a 48-hour treatment with ELE can be due to toxicity) and no antimutagenic action of the EFE treatment against the aneugenic and/or clastogenic activities of MMC.