Expression and function analysis of FaCO gene in Festuca arundinacea / 生物工程学报

Photoperiod plays an important role in transformation from vegetative growth to reproductive growth in plants. CONSTANS (CO), as a unique gene in the photoperiod pathway, responds to changes of day length to initiate flowering in the plant. In this study, the expression level of FaCONSTANS (FaCO) gene under long-day, short-day, continuous light and continuous darkness conditions was analyzed by real-time quantitative PCR. We constructed the over-expression vector p1300-FaCO and infected into Arabidopsis thaliana by Agrobacterium-mediated method. We constructed the silencing vector p1300-FaCO-RNAi and infected into Festuca arundinacea by Agrobacterium-mediated method. The expression of FaCO gene was regulated by photoperiod. The over-expression of FaCO promoted flowering in wild type of Arabidopsis thaliana under long day condition and rescued the late flowering phenotype in co-2 mutant of Arabidopsis thaliana. Silencing FaCO gene in Festuca arundinacea by RNAi showed late-flowering phenotype or always kept in the vegetative growth stage. Our understanding the function of FaCO in flowering regulation will help further understand biological function of this gene in Festuca arundinacea.

Differences in the fly-load of Haematobia irritans (Diptera: Muscidae) on cattle is modified by endophyte infection of pastures

Background: The horn fly, Haematobia irritans, is an obligate bloodsucking ectoparasite of pastured cattle and is a major pest of livestock production in North and South America and Europe. In this study, we investigated the potential to use cattle pastures, infected with non-toxic, "friendly" fungal-endophyte-infected (E+) tall fescue, Festuca arundinacea Schreb., as a strategy for reducing horn fly loads in cattle, and to evaluate the possible bioinsecticide effect on horn fly larvae. Results: When cattle grazed in E+ tall fescue, a decrease in fly-load was observed, compared with other pastures (endophyte-free (E-) pastures). The infestation of horn fly load decreased according to an increase in the percentage of endophyte present in the different pastures (0 to 100%). Moreover, two groups of animals with significant differences in the fly-load (high and low fly-load) in the same herd were observed (P < 0.05). Additionally, it was possible to determine a bioinsecticide effect of cattle dung, upon horn fly larvae (80%), from animals fed E+ tall fescue. Conclusions: These results constitute the first report on the potential for exploiting pasture management for controlling 1) horn fly-loads on cattle and 2) the normal development of horn fly larvae. In conclusion, this information provides preliminary understanding of the role of cattle pasture diet management for controlling horn fliesas part of an integrated pest management strategy for this major pest of farmed livestock.

Genetic similarities among Iranian populations of Festuca, Lolium, Bromus and Agropyron using amplified fragments length polymorphism [AFLP] markers

The study of genetic variation and phylogenetic relationships is essential for the efficient selection of superior plant material and conducting introgression breeding programs. In Iran, despite the wide geographical distribution of grasses no report is available on the genetic diversity and relationships of cool season grass populations. In this study amplified fragment length polymorphism [AFLP] was used to study 42 populations from eight species of Festuca arundinacea Schereb., Festuca. pratensis Huds., Festuca. rubra L., Festuca. ovina L., Lolium perenne L., L. rigidum Gaud., Bromus tomentellus Boiss. and Agropyron cristatum [L] Gaertn. The number of amplified products ranged from 11 to 78 per primer combination and a total of 497 markers were scored. Jaccard's genetic similarity coefficients among populations ranged from 0.15 to 0.88 showing high levels of inter and intra-specific genetic diversity. The cluster analysis and principle coordinate analysis [PCOA] reflected the phylogenetic relationships among species and clearly demonstrated differences in the degree of similarity among accessions. Results indicated that AFLP is a useful technique to reveal genetic diversity at different taxonomic levels of grasses and might facilitate the selective introgression of useful genes in plant breeding programs

Development of new sensitizations in asthmatic children monosensitized to house dust mite by specific immunotherapy.

It has been hypothesized that specific immunotherapy (SIT) significantly decreases the development of new allergen sensitizations in mono-sensitized patients. In this study, we evaluated the effect of SIT on the development of new allergen sensitizations in 129 asthmatic children mono-sensitized to house dust mite. SIT was accepted by only 70 of them (SIT group). The remaining 59 children were treated only with medication (control group). At the end of the study we found that 33% of all patients developed new sensitizations. Surprisingly, the prevalence of new sensitizations was significantly higher in the SIT group (45.5%) than in the control group (18.1 %). Ash tree (Fraxinus excelsior), Olive and Meadow fescue (Festuca elatior) were the most common allergens responsible for the new sensitizations. We conclude that SIT did not prevent the onset of new sensitizations in asthmatic children mono-sensitized to house dust mite.