Protocolo de detección de bacterias viables por QPCR

Este trabajo forma parte de los proyectos RTI2018-96018-R-C31 y PID2021- 123600OR, financiados por MCIN/ AEI /10.13039/501100011033/ y por “FEDER Una manera de hacer Europa”

Biocontrol of tomato wilt by Penicillium oxalicum formulations in different crop conditions

Eight formulations of Penicillium oxalicum (FOR1 to FOR8) were obtained by the addition of various ingredients, in two separate steps of the production and drying of P. oxalicum conidia. These formulations were then evaluated against tomato wilt in three glasshouse (G1 to G3) and two field (F1 and F2) experiments. All formulations were applied to seedlings in seedbeds 7 days before transplanting at a rate of 107 spores g-1 seedbed substrate. The conidial viability of each formulation was estimated by measuring germination just after fluid bed-drying, before seedbed application and after 1 and 2 years of storage at 4 °C under vacuum. The densities of P. oxalicum were estimated in the seedbed substrate and in the rhizosphere of three plants per treatment just before transplanting. Initial conidial viability of formulations just after fluid bed-drying was approx. 80%, except for FOR1, FOR4, and FOR7 which were 60%. The initial viability was maintained up to 40-50% for 2 years of storage at 4 °C under vacuum, except for FOR1. All formulations had {greater than or slanted equal to}50% viability at application time. Populations of P. oxalicum in the seedbed substrate just before transplanting were >106 cfu g-1 soil in G3 and F2; populations in rhizosphere were also >106 cfu g-1 fresh root, except for FOR3, FOR5, and FOR6 in G2. A range of 22-64% of disease reduction was observed with all formulations, although these reductions were not significant (p = 0.05) for FOR1, FOR4, and FOR5 in any experiment. Contrast analysis showed significant differences between biological treatments and untreated control (p = 0.05) in all experiments, but no significant differences between biological and chemical treatments. Initial conidial viability of P. oxalicum in formulations and populations of P. oxalicum in the seedbed substrate explained 78.26% of the variability in P. oxalicum populations in tomato rhizosphere before transplanting. Disease incidence in untreated plants was negatively correlated (r = -0.54) with the percentage of disease control. The relationship between the viability of formulations, the populations of P. oxalicum in seedbed and rhizosphere, and the control of tomato wilt is discussed

Development of a dried Penicillium oxalicum conidial formulation for use as a biological agent against Fusarium wilt of tomato Selection of optimal additives and storage conditions for maintaining conidial viability

The fungus, Penicillium oxalicum Thom.;has been proposed as a biocontrol agent against vascular wilts caused by Verticillium spp.;Fusarium oxysporum. In this paper, we report our findings on the effects of different additives and storage conditions of varying durations, temperatures, and types on the viability and biocontrol efficacy of three different types of P. oxalicum conidial formulations. The viability of the three different P. oxalicum conidial formulations with various solvent stabilizers and moisture contents between <5% and 21% was determined after their preparation and storage with or without vacuum for as long as one year at temperatures that ranged from 4 to 50°C. The results were compared to those obtained using a dried conidial formulation that was prepared from fresh conidia without any solvent stabilizers. After conducting a series of laboratory assays, and several glasshouse and field experiments over two growing seasons with the different types of conidial formulations, we found that a P. oxalicum conidial formulation with biocontrol efficacy and a long shelf life for controlling Fusarium tomato wilts can be a non-vacuum-packed or vacuum-packed formulation that contains 1.5% sodium alginate, 20% glycerol, 5% sucrose and 5% sorbitol and has <15% moisture content. Although the results on the efficacy of this biocontrol product are promising when the disease pressure of Fusarium wilt is moderate, this P. oxalicum formulation will still need to be improved in order to develop a commercial product that will be efficacious when the disease pressure of Fusarium wilt is high. © 2010 Elsevier Inc

Detección de células viables y no viables de Xanthomonar arboricola pv. Pruni

Publishe

Management Fusarium wilt on melon and watermelon by Penicillium oxalicum

The potential of the biological control fungus Penicillium oxalicum to suppress wilt caused by Fusarium oxysporum f. sp. melonis and F. oxysporum f. sp. niveum on melon and watermelon, respectively, was tested under different growth conditions. The area under disease progress curve of F. oxysporum f. sp. melonis infected melon plants was significantly reduced in growth chamber and field experiments. In glasshouse experiments, it was necessary to apply P. oxalicum and dazomet in order to reduce Fusarium wilt severity in melons caused by F. oxysporum f. sp. melonis. For watermelons, we found that P. oxalicum alone reduced the area under the disease progress curve by 58% in the growth chamber experiments and 54% in the glasshouse experiments. From these results, we suggested that P. oxalicum may be effective for the management of Fusarium wilt in melon and watermelon plants

Relationship between number and type of adhesions of Penicillium oxalicum conidia to tomato roots and biological control of tomato wilt

We studied (a) the extent adhesion of Penicillium oxalicum conidia to tomato roots after application of P. oxalicum conidial formulations with or without stickers, (b) the relationship between the extent of conidial adhesion to roots and biocontrol of the conidial formulations against tomato wilt, and (c) colonisation of roots by P. oxalicum. Adhesion of P. oxalicum conidia to tomato roots occurred within the first minute of contact between the root and the conidial formulation and the bonding strength was sufficiently strong to prevent conidial removal from the roots. In addition, some formulations with stickers that increased conidial adhesion to roots improved the biocontrol of tomato wilt, when compared to that of formulations without stickers. A "dried conidia without stickers" with 0.025% Nu-Film 17 had no effect on the biocontrol of tomato wilt, despite good adherence of the conidia to the roots. The numbers of P. oxalicum conidia that adhered to the roots was constant for 60 days after application of a "dried conidia without stickers" conidial formulation. The significance of these results (speed of adhesion, number of adhered conidia, and variability of conidial external surface) are discussed in relation to the biocontrol success of tomato wilt using different types of conidial formulations with and without stickers. © 2008 Elsevier Inc. All rights reserved

Biocontrol of Fusarium and Verticillium wilt of tomato by Penicillium oxalicum under greenhouse and field conditions

Treatments with conidia of Penicillium oxalicum produced in a solid-state fermentation system were applied at similar densities (6 × 106 spores/g seedbed substrate) to tomato seedbeds in water suspensions (T1 5 days before sowing, or T2 7 days before transplanting; 15 days after sowing), or in mixture with the production substrate (T3 7 days before transplanting; 15 days after sowing). Treatments T2 and T3 significantly (P = 0.05) reduced fusarium wilt of tomato in both greenhouse (artificial inoculation) (33 and 28%, respectively) and field conditions (naturally infested soils) (51 and 72%, respectively), while treatment T1 was efficient only in greenhouse (52%). Verticillium wilt disease reduction was obtained with T3 in two field experiments (56 and 46%, respectively), while T1 and T2 reduced disease only in one field experiment (52% for both T1 and T2). Treatment with conidia of P. oxalicum plus fermentation substrate (T3) resulted in better establishment of a stable and effective population of P. oxalicum in seedbed soil and rhizosphere providing populations of approx. 107 CFU/g soil before transplanting. Results indicate that it will be necessary to apply P. oxalicum at a rate of approx. 106-107 CFU/g in seedbed substrate and rhizosphere before transplanting for effective control of fusarium and verticillium wilt of tomato, and that formulation of P. oxalicum has a substantial influence on its efficacy

Características asociadas a los primeros estadíos de infección de aislados españoles de Xanthomonas arboricola pv. pruni

Publishe