Effect of plant growth promoting rhizobacterial (PGPR) inoculation on growth in tomato (Solanum Lycopersicum L.) and characterization for direct PGP abilities in Morocco

Plant Growth promoting rhizobacteria are a heterogeneous group of bacteria that can be found in the rhizosphere, at root surfaces and in association with roots. They benefit plants through Production of plant hormones, such as auxins, asymbiotic N2 fixation, solubilization of mineral phosphates, antagonism against phytopathogenic microorganisms by production of antibiotics, siderophroes, Chitinase and other nutrients ability to effectively colonize roots are responsible for plant growth promotion. An experiment was conducted in the field of National Institute of Agronomic Research of Meknes. Morocco. The experiment was a completely randomized design with six replicates. There were four treatments viz. T1: (control; N0 -PGPR), T2: (N0 +2027-2), T3: (N0 +2066-7) and T4: (N0+2025-1). The results indicated that a remarkable increase in root growth, namely length, the diameter of the rod and the total chlorophyll. A total of three different bacteria colonies were isolated and proceed with in vitro screening for plant growth promoting activities; phosphate solubilization, nitrogen fixation, indole acetic acid (IAA), ammonia production and antimicrobial enzymes (cellulose, chitinase and protease) activity. Among the three bacterial strains, all bacterial strains are able to produce ammonia, IAA production and nitrogen fixation activity, one strain phosphate solubilizing activity, two strain are able to produce cellulase syntheses, Protease activity and Chitinase activity

Rapid and sensitive methods for detection of Allorhizobium vitis, causal agent of grapevine crown gall

A rapid method and sensitive methods for extraction of bacterial DNA from pure culture and directly from plant materiel were compared in polymerase chain reaction with specific primers VCF3/VCR3 to see the reliable method that can used in the detection of tumorigenic strain of Allorhizobium vitis causal agent of grapevine crown gall. From the three tested methods of DNA extraction from pure culture, the alkaline method is the most effective technique for the extraction presenting a high sensitivity with a detection threshold equal to 5.104 CFU/ml. Five different protocols for extracting bacterial DNA from plant tissues of infected tomato, based on the use of an extraction buffer, were tested to see its usefulness in detecting pathogenic strain of A. vitisS4. Two protocols based on the use of Triton X-100 and Tween 20 were efficient for detecting A. vitis S4 directly from tomato tumors with a sensitivity of 103 CFU/ml for the both protocols. Consequently, these protocols were proposed as specific protocols for the detection of tumorigenic strain of A. vitis from symptomatic and asymptomatic plants

Aureobasidium pullulans strain Ach1-1 in biocontrol of postharvest diseases of apples: 15 crucial years of research before starting commercial development

Significant losses in harvested fruits are directly attributable to decaying fungi. Biological control using microbial agents including yeasts has been reported among several alternatives to the use of synthetic chemical fungicides for managing postharvest fruit decay. Economic losses caused by postharvest diseases represent one of the main problems of the apple industry worldwide. The major diseases affecting citrus are the "green mold" and "blue mold", caused by Penicillium digitatum and P. italicum, respectively. To control them, synthetic fungicides are the most commonly used method. However, often the emergence of resistant strains occurs and their use is becoming more restricted because of toxic effects and environmental pollution they generate, combined with trade barriers to international markets. The aim of this work was to isolate indigenous killer yeasts Postharvest fungal pathogens are considered the main cause of fresh fruits losses in storage conditions. As a countermeasure yeasts showed to be potential candidates for an efficient biocontrol of postharvest pathogens since they colonize efficiently and steadily wounded and non-wounded plant surfaces even under unfavourable conditions. The aim This led us to select in vivo a potential yeast biocontrol agent able to protect apple fruits in particular, against the fungi Penicillium expansum and Botrytis cinerea in postharvest conditions. The yeast antagonist isolated form the surface of Golden Delicious apple fruit and characterized as Aureobasidium pullulans strain Ach1-1, showed significant ability in controlling blue and grey mold infection diseases. Efficacy results revealed that A. pullulans strain Ach1-1 allowed high protection level (85%) against the two tested pathogens at 25°C and in storage conditions [1]. Many challenges needs to be addressed in order to develop a successful postharvest Biocontrol Agent. From a commercial point of view, a deep understanding of the action mode is essential to develop appropriate formulation, methods of application, and to obtain registration. In this regard, the possible involvement of competition for nutrients in the biocontrol activity of this strain both in vitro and in situ was investigated. The results showed evidence that competition for apple nutrients mainly amino acids and especially Serine, reflects the potential mechanism of strain Ach1-1 biocontrol activity against blue mold infection disease [2]. Special emphasis will be taken to these results. Their implication on the formulation will be further presented. Besides, in an attempt to monitor the population dynamic of A. pullulans strain X on fruit surface, molecular markers and a semi-selective medium method were developed. The random amplified polymorphic DNA (RAPD) technique was applied to a collection of 15 strains of A. pullulans, including the strain Ach1-1. Five specific RAPD fragments were amplified for strain Ach1-1, among them, a fragment of 528 bp specific to this strain was selected, cloned, sequenced, and used to design sequence-characterized amplified region (SCAR) primers. The results showed that the SCAR primers can clearly identify strains Ach1-1 among 14 strains of A. pullulans and among eight yeast strains commonly present on apple fruit surfaces. In addition a semi-selective medium, PDA medium supplemented with euparen, sumico, hygromycin B, streptomycin sulphate, cycloheximide, was developed. These two methods displayed sufficient and high accuracy to monitor strain Ach1-1 populations [3]. Finally, a first trial of biomass production, formulation and evaluation of the formulated yeast for its antagonistic activity at pilot scale was conducted. The results showed high protection level achieved with the formulated A. pullulans strain Ach1-1 towards controlling apple decay caused by Penicillium expansum after 28 and 7 days stored respectively at 5 and 25°C [4]. Based on these crucial steps, Aureobasidium pullulans strain Ach1-1 gained a step stone in fundamental and applied research, leading to a collaboration establishment with Elephant vert group towards its commercial development as potential biocontrol agent for postharvest apple diseases.Développement d’une formulation de biocontrôle à base d’Aureobasidium pullulans Ach1.1 contre des pathogènes de cultures maraîchère et fruitières en pré et post-récolt