Endophytic colonization and <i>in planta </i>nitrogen fixation by a diazotrophic <i>Serratia </i>sp. in rice

802-807Nitrogen fixing endophytic Serratia sp. was isolated from rice and characterized. Re-colonization ability of Serratia sp. in the rice seedlings as endophyte was studied under laboratory condition. For detecting the re-colonization potential in the rice seedlings, Serratia sp. was marked with reporter genes (egfp and Km′) using transposon mutagenesis. The conjugants were screened for re-colonization ability and presence of nif genes using PCR. Further, the influence of flavonoids and growth hormones on the endophytic colonization and in planta nitrogen fixation of Serratia was also investigated. The flavonoids, quercetin (3μg /ml) and diadzein (2 μg/ml) significantly increased the re-colonization ability of the endophytic Serratia, whereas the growth hormones like IAA and NAA (5 μg/ml) reduced the endophytic colonization ability of Serratia sp. Similarly, the in planta nitrogen fixation by Serratia sp. in rice was significantly increased due to flavonoids. The inoculation of endophytic diazotrophs increased the plant biomass and biochemical constituents

Bacterial Endophytes of Plants: Diversity, Invasion Mechanisms and Effects on the Host

Plant inner tissues are colonized by bacterial organisms known as endophytes. The relatively recent application of culture independent and molecular high throughput techniques allowed the description of a large diversity of endophytic bacterial taxa. These microorganisms can be found in any plant organ, including fruits and legume nodules. Some endophytic bacteria benefit the host by several mechanisms, and their application to economically important crops represents an interesting alternative to the use of agrochemicals. However, more studies are required to clearly assess their effects on the hosts (especially in co-inoculation with other beneficial bacteria) and the molecular events that lead to the interaction between plants and endophytic microorganisms. In this chapter, we focus on bacterial endophytes from legumes and non-legumes plants, analyzing their diversity and effects on the hosts. We also discuss the endophytic colonization of legume nodules, with emphasis on the endophytic bacterial diversity, the mechanisms involved in the nodule invasion and their effects on the hosts.Fil: Ibañez, Fernando Julio. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Tonelli, Maria Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; ArgentinaFil: Muñoz, Vanina Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Figueredo, María Soledad. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Fabra, Adriana Isidora. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentin