Trichoderma as a biological agent of Fusarium oxysporum species complex and Vigna unguiculata growth promoter

European Journal of Plant Pathology - This study aimed to evaluate the potential antagonistic role of Trichoderma in the control of Fusarium isolates belonging to the Fusarium oxysporum species...     

Improving the estimation of soil water evaporation based on days after wetting

Soil evaporation constitutes a major pathway of water loss in agriculture. Understanding its dynamics in the face of drying and soil cover is fundamental to improve both simulation models and the sustainability of production systems. Thus, the objective of this study was to estimate soil evaporation as a function of drying and percentage of soil cover. Three experiments were carried out in three different periods. In each of the periods, in parallel and in an adjacent area, an experiment was carried out to evaluate the influence of weighing micro-lysimeter (ML) height on the estimation of direct soil evaporation. The experiments were installed with a completely randomized design. For the experiments that measured evaporation as a function of cover, the treatments consisted of six different percentages of cover of the internal area of the ML (0%, 10%, 25%, 50%, 75% and 100%), with four replicates, using artificial plants to cover the soil. The experiments that estimated evaporation as a function of ML height were conducted with eight repetitions and three different ML heights (100, 200 and 300 mm). It was observed that the accumulated evaporation up to 25 days after wetting was 52% and 53% lower in micro-lysimeters with 100 mm height, compared to those with 200 and 300 mm height, respectively, for all experiments. The new model developed to calculate soil evaporation as a function of the days after wetting and percentage of soil cover showed excellent performance (NSE > 0.95).     

Lunasin and Bowman-Birk protease inhibitor concentrations of protein extracts from enzyme-assisted aqueous extraction of soybeans

Lunasin and Bowman-Birk protease inhibitor (BBI) are two soybean peptides to which health-promoting properties have been attributed. Concentrations of these peptides were determined in skim fractions produced by enzyme-assisted aqueous extraction processing (EAEP) of extruded full-fat soybean flakes (an alternative to extracting oil from soybeans with hexane) and compared with similar extracts from hexane-defatted soybean meal. Oil and protein were extracted by using countercurrent two-stage EAEP of soybeans at 1:6 solids-to-liquid ratio, 50 °C, pH 9.0, and 120 rpm for 1 h. Protein-rich skim fractions were produced from extruded full-fat soybean flakes using different enzyme strategies in EAEP: 0.5% protease (wt/g extruded flakes) used in both extraction stages; 0.5% protease used only in the second extraction stage; no enzyme used in either extraction stage. Countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes was used as a control. Protein extraction yields increased from 66% to 89-96% when using countercurrent two-stage EAEP with extruded full-fat flakes compared to 85% when using countercurrent two-stage protein extraction of air-desolventized, hexane-defatted soybean flakes. Extruding full-fat soybean flakes reduced BBI activity. Enzymatic hydrolysis reduced BBI contents of EAEP skims. Lunasin, however, was more resistant to both enzymatic hydrolysis and heat denaturation. Although using enzymes in both EAEP extraction stages yielded the highest protein and oil extractions, reducing enzyme use to only the second stage preserved much of the BBI and Lunasin.     

Araucaria angustifolia (Bert.) O. Kuntze induces oxidative and genotoxic damage in larvae of Anticarsia gemmatalis Hübner (Lepidoptera: Erebidae)

Plant-derived products have been considered as an important alternative to common pesticides. Araucaria angustifolia extract (AAE) contains high levels of polyphenols, which are correlated with mortality in defoliating insects. Therefore, this study aimed to evaluate the effects of AAE treatments on A. gemmatalis larvae. Results showed that AAE was able to induce lipid, protein, and DNA damage in the larvae via oxidative stress. AAE treatment did not induce larvae mortality; however, there was an increase in the number of malformed pupae, along with a decrease in the emergence of the insects. These biological effects may be correlated with the polyphenol content of the AAE.     

Genomic selection allowing for marker‐by‐environment interaction

Genomic selection has been routinely implemented in plant breeding in two stages. The first stage usually omits the marker information and estimates adjusted means of genotypes across environments. The second stage uses the adjusted means to predict genomic breeding values. However, if the effects of markers vary substantially between different environments, it may be important to account for this variation for varieties adapted to different environments. Using two maize data sets, we investigated whether modelling the marker‐by‐environment interaction can improve the predictive ability of genomic selection relative to modelling genotype‐by‐environment interaction alone. Modelling the marker‐by‐environment interaction did not substantially increase the predictive ability relative to modelling only the genotype‐by‐environment interaction for the two tested data sets. Thus, genomic selection, carried out in a stagewise fashion, such that the marker information is omitted until the last stage of the process, may suffice for most practical purposes. Moreover, predictive ability did not reduce substantially even when the number of markers with consistent effects across environments used for genomic prediction was reduced to about 50.     

Improving in vitro induction of autopolyploidy in grapevine seedless cultivars

The efficiency of in vitro polyploidization depends on several variables associated to the plant, the antimicrotubule agent and the interactions between them. In the present work, we have used response-surface methodology to determine the best operating conditions for plant recovery in polyploidization assays for shoot apices and somatic embryos of two seedless grape cultivars, employing colchicine and oryzalin. Explant type, tubulin-interfering compound and concentration were the critical factors determining plant recovery. Linear reduction in viable plant regeneration via organogenesis and somatic embryogenesis was obtained by increasing oryzalin concentrations and treatment time, whereas the effects of colchicine were better described by a quadratic design for both explants types. The conditions promoting higher rates of plant recovery were used in chromosome doubling experiments with oryzalin and colchicine for shoot apices and somatic embryos of ‘Crimson seedless’ and ‘BRS Clara’. The established protocols allowed the recovery of non-chimerical autotetraploid plants at rates higher than 30 % for both cultivars. Stomata size parameters statistically correlate to the ploidy level of the regenerants and were effective for preliminary polyploidy screening. Autotetraploid lines of seedless grapes were incorporated into the Vitis germplasm bank for further agronomical evaluations. To our knowledge, this is the first report of in vitro oryzalin induced polyploidization of grapevine and of the use of mathematical modeling to optimize chromosome doubling in plants.