Flavonoids and Growth Hormones Influence Endophytic Colonization and in Planta Nitrogen Fixation by a Diazotrophic Serratia sp. in Rice

Abstract

Several endophytic diazotrophs were isolated from cultivars of rice and screened for their diazotrophy by nitrogenase assay and amplification of partial nifH gene. Ability of one of the diazotrophic endophytes, Serratia sp. (isolate EDA2 from cultivar ADT36) to colonize the rice seedlings grown in the presence of flavonoids and growth hormones, under gnotobiotic condition was assessed in cultivar ADT36 using a strain marked with transposonbased egfp and Km r . The endophytic colonization was monitored through re-isolation from different parts of rice seedlings in LB+Km plates. Addition of the flavonoids quercetin and diadzein to the growth medium increased the extent of endophytic colonization of the conjugant in rice seedlings by colonizing throughout the plant. Population and in planta nitrogenase activity of Serratia in rice seedlings were significantly increased by addition of flavonoids, quercetin and diadzein, whereas growth hormones, IAA and NAA reduced the efficiency of Serratia. The inoculation of Serratia sp. with flavonoids increased the plant biomass and biochemical constituents of rice seedlings under controlled condition.

Naringenin degradation by the endophytic diazotroph Herbaspirillum seropedicae SmR1

“…Flavonoids can also stimulate endophytic colonization of rice by Serratia spp. (Balachandar et al, 2006) and colonization of Arabidopsis thaliana by Herbaspirillum seropedicae (Gough et al, 1997).…”

The structure of the culturable root bacterial endophyte community of Nicotiana attenuata is organized by soil composition and host plant ethylene production and perception

“…Numerous studies have characterized bacterial diversity in scores of plants, and have reported that the bacterial endophyte community can be specific to particular species of host plants and even cultivars (Sturz et al, 1997;Adams & Kloepper, 2002;Araujo et al, 2002;Zinniel et al, 2002;Rasche et al, 2006;Sun et al, 2008). The composition of root exudates is thought to play a central role in recruiting bacteria from the bulk soil into the rhizosphere (Bais et al, 2006;Hartmann et al, 2009;Micallef et al, 2009) and, finally, into the endosphere (Balachandar et al, 2006), but little is known about specific plant genes that facilitate the recognition and selection of endophytic bacteria.…”

In silico prediction and expression profile analysis of small non-coding RNAs in Herbaspirillum seropedicae SmR1

“…Plants also play an important role in establishing this interaction since they produce compounds that affect their associations with microorganisms. One of such compounds is naringenin, a flavonoid produced as secondary metabolite, that can stimulate or inhibit specific genetic responses in different bacteria associated with plants [14,15]. It was demonstrated that naringenin stimulates the endophytic colonization of Arabidopsis thaliana by H. seropedicae Z67 [16].…”