Identification and Characterization of a Pseudomonas mosselii strain and its Antibacterial Function against Agrobacterium tumefaciens

Agrobacterium tumefaciens is a gram negative bacterial that can infect a range of plants and result in root crown gall. A total number of 10328 bacterial strains were isolated from rhizosphere of cherry tree. One strain of LWB10 showed clear inhibition zone around the bacterial colony in YEB media inoculated with A. tumefaciens C58. Morphological, physiological, and biochemical characterization indicated that LWB10 belongs to member of the genus Pseudomonas. Results from the high-throughput matrix-assisted laser desorption/ionization biotypersmart system indicated that this strain had a score value of 2.247 relative to Pseudomonas mosselii. Also, phylogenetic analysis based on 16S rRNA gene sequence showed that strain LWB10 shared the highest similarity with Pseudomonas mosselii CIP 105259T. The antagonist strains also exhibit well in growth inhibition of other five A. tumefaciens strains. Coinoculation of LWB10 and plant pathogenic strain of A. tumefaciens CFCC1369 showed strongly inhibition of tumor formation in tomato stems. All the results demonstrated that the isolated strain is P. mosselii LWB10 and its antibacterial ability to A. tumefaciens may offer new way for management of crown gall disease in the future. Keywords: Agrobacterium tumefaciens, Pseudomonas mosselii, antagonist, biological control

Oxidative stress and antioxidant defense in Brassicaceae plants under abiotic stresses

Brassicaceae plants, as an important source of primary and secondary metabolites, are becoming a research model in plant science. Plants have developed different ways to ward off environmental stress factors. This is lead to the activation of various defense mechanisms resulting in a qualitative and/or quantitative change in plant metabolite production. Reactive oxygen species (ROS) is being continuously produced in cell during normal cellular processes. Under stress conditions, there are excessive production of ROS causing progressive oxidative damage and ultimately cell death. Despite their destructive activity, ROS are considered as important secondary messengers of signaling pathway that control metabolic fluxes and a variety of cellular processes. Plant response to environmental stress depends on the delicate equilibrium between ROS production, and their scavenging. This balance of ROS level is required for performing its dual role of acting as a defensive molecule in signaling pathway or a destructive molecule. Efficient scavenging of ROS produced during various environmental stresses requires the action of several non-enzymatic as well as enzymatic antioxidants present in the tissues. In this review, we describe the ROS production and its turnover and the role of ROS as messenger molecules as well as inducers of oxidative damage in Brassicaceae plants. Further, the antioxidant defense mechanisms comprising of enzymatic and non-enzymatic antioxidants have been discussed. Keywords: Abiotic stress, Antioxidant defence, Brassicaceae, Oxidative stress, ROS