Colonization of <Emphasis Type="Italic">Arabidopsis</Emphasis> roots by <Emphasis Type="Italic">Trichoderma atroviride</Emphasis> promotes growth and enhances systemic disease resistance through jasmonic acid/ethylene and salicylic acid pathways

Trichoderma spp. are common soil fungi used as biocontrol agents due to their capacity to produce antibiotics, induce systemic resistance in plants and parasitize phytopathogenic fungi of major agricultural importance. The present study investigated whether colonization of Arabidopsis thaliana seedlings by Trichoderma atroviride affected plant growth and development. Here it is shown that T. atroviride promotes growth in Arabidopsis. Moreover, T. atroviride produced indole compounds in liquid cultures. These results suggest that indoleacetic acid-related indoles (IAA-related indoles) produced by T. atroviride may have a stimulatory effect on plant growth. In addition, whether colonization of Arabidopsis roots by T. atroviride can induce systemic protection against foliar pathogens was tested. Arabidopsis roots inoculation with T. atroviride provided systemic protection to the leaves inoculated with bacterial and fungal pathogens. To investigate the possible pathway involved in the systemic resistance induced by T. atroviride, the expression profile of salicylic acid, jasmonic acid/ethylene, oxidative burst and camalexin related genes was assessed in Arabidopsis. T. atroviride induced an overlapped expression of defence-related genes of SA and JA/ET pathways, and of the gene involved in the synthesis of the antimicrobial phytoalexin, camalexin, both locally and systemically. This is the first report where colonization of Arabidopsis roots by T. atroviride induces the expression of SA and JA/ET pathways simultaneously to confer resistance against hemibiotrophic and necrotrophic phytopathogens. The beneficial effects induced by the inoculation of Arabidopsis roots with T. atroviride and the induction of the plant defence system suggest a molecular dialogue between these organisms.     

Studies on proofing of yeasted bread dough using near- and mid-infrared spectroscopy

Dough proofing is the resting period after mixing during which fermentation commences. Optimum dough proofing is important for production of high quality bread. Near- and mid-infrared spectroscopies have been used with some success to investigate macromolecular changes during dough mixing. In this work, both techniques were applied to a preliminary study of flour doughs during proofing. Spectra were collected contemporaneously by NIR (750-1100 nm) and MIR (4000-600 cm(-1)) instruments using a fiberoptic surface interactance probe and horizontal ATR cell, respectively. Studies were performed on flours of differing baking quality; these included strong baker's flour, retail flour, and gluten-free flour. Following principal component analysis, changes in the recorded spectral signals could be followed over time. It is apparent from the results that both vibrational spectroscopic techniques can identify changes in flour doughs during proofing and that it is possible to suggest which macromolecular species are involved.     

Behavior of sheep fed babassu cake (Orbygnia speciosa) as a substitution for elephant grass silage

This study aimed to evaluate the behavior of sheep fed babassu cake as a substitution for elephant grass silage. The experiment was conducted at the Federal Rural University of Amazonia (Universidade Federal Rural da Amazônia ‐ UFRA), Brazil, using 45 sheep housed in individual stalls, with unlimited access to feed and distributed in a completely randomized design with five treatments (0, 12.5, 25, 37.5 and 50% inclusion of babassu cake) and nine replications. All of the treatments contained a roughage‐to‐concentrate ratio of 40:60. No differences were observed in the time spent feeding (P > 0.05), regardless of the source of roughage used. However, there was a reduction in the time spent in rumination (P < 0.05) and an increase in time spent idling (P < 0.05) when babassu cake was included in the diet. Although there was a reduction in the time spent chewing the ruminal bolus (P < 0.05), the total daily chewing time was the same for all animals (P > 0.05). However, the sheep fed babassu cake showed higher feeding and rumination efficiency (P < 0.05). Therefore, the substitution of elephant grass silage with babassu cake can be performed at up to 50% without compromising the total time spent eating and chewing, which allows increased feeding and rumination efficiency.     

Evaluation of shelf-life of fresh-cut pineapple using FT-NIR and FT-IR spectroscopy

The aim of this work was to investigate the loss of freshness of fresh-cut pineapple samples stored at different temperatures using non-destructive spectroscopic methods. Three lots of fresh cut pineapples (Ananas comosus L. cv. Golden Ripe, from Costa Rica), packaged in PVC trays (250 g) were analyzed during storage at three different temperatures (5.3, 8.6 and 15.8 °C). Loss of quality of these fruit was evaluated by chemical and microbiological parameters and using NIR and MIR spectroscopy. The FT-NIR spectra were acquired in reflectance mode directly on the slice of fresh-cut pineapple, over the range 12,500–3900 cm⁻¹, while FT-IR spectra were collected over the range 4000–700 cm⁻¹ using an horizontal ATR cell. Some chemical and microbiological parameters were also measured. Principal component analysis (PCA) was applied to the second derivative of the spectra to uncover molecular modifications occurring over the storage time. A clear discrimination between “fresh” and “old” samples was obtained and a stability time corresponding to the time of the initial loss of freshness was defined at each temperature. The stability times revealed by NIR spectroscopy were in good accordance with those evaluated by MIR. At each temperature the stability times (i.e. the initial loss of freshness times) defined by spectroscopic techniques (4–5 d at 5.3 °C, 3–4 d at 8.6 °C and 1 d at 15.8 °C) were associated with a mesophilic bacteria count ranging between 10⁵ and 10⁶ CFU g⁻¹ and lower than the maximum limit for mesophilic bacteria (<5 × 10⁷ CFU g⁻¹) given by French hygienic regulations at consumption.These results show that NIR and MIR spectroscopy could support conventional techniques (chemical and microbiological analysis) in studying shelf-life of fresh-cut fruit. In particular these techniques define the initial loss of freshness time, indicating a product which rapidly will be no longer acceptable if stored beyond that time. The main advantage of using IR spectroscopic techniques is to rapidly draw a profile of the product related to its change in quality.     

Efficacy and economics of ground cover management as a conservation biological control strategy against Tetranychus urticae in clementine mandarin orchards

Conservation biological control by means of ground cover offers an interesting alternative to chemical control of the twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae), a key pest of clementine mandarins. The aim of this study was to investigate whether this tactic could actually achieve significant reductions in crop losses caused by this pest. The three most common cover practices used in citrus in Spain were compared: wild cover, a cover of Festuca arundinacea Scherb. (Poaceae), and bare soil. The action threshold was more often exceeded in wild cover than in bare soil or F. arundinacea. When expenditures and revenues were balanced, the most favorable cover was F. arundinacea (between 44.4 and 74.5% cost reduction relative to the most expensive one). F. arundinacea as a cover crop is a conservation biological control strategy highly recommendable for clementine producers. Although its use did not reduce mite populations below the action threshold, the population decreases obtained made the adoption of this tactic a beneficial alternative both ecologically and economically.     

Effect of ground cover management on Thysanoptera (thrips) in clementine mandarin orchards

Conservation biological control by means of ground cover offers an interesting alternative to chemical control. A complex of Thysanoptera (thrips) species inhabits citrus, some of which are considered pests. This study investigated the effect of ground cover management on thrips species composition, distribution, and seasonal abundance in four commercial clementine mandarin (Citrus clementina Tanaka) orchards. Three soil management systems were compared: resident vegetation, Festuca arundinacea Schreber (Poales: Poaceae), and bare soil. Cover management affected thrips species diversity and abundance. Two of the main species causing fruit damage in Spanish citrus, Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman, were abundant in the resident ground cover. However, their abundance was strongly depressed in the F. arundinacea cover. The resident vegetation cover could provide a range of suitable host plants supporting populations of potential thrips pest species beyond the citrus blooming period. The F. arundinacea cover, which hosted Poaceae-specific thrips species, could also provide alternative food sources for Phytoseiidae mites. These predatory mites could reduce populations of potential thrips and other citrus pests below economic injury level. Our results confirm the suitability of F. arundinacea as a cover crop for clementine mandarins.