A N₂-fixing endophyticBurkholderiasp. associated with maize plants cultivated in Mexico

Abstract

In the frame of a survey of potentially endophytic N2-fixing Burkholderia associated with maize in Mexico, its country of origin, the soil of an indigenous maize field near Oaxaca was studied. Under laboratory conditions, plant seedlings of two ancient maize varieties were used as a trap to select endophyte candidates from the soil sample. Among the N2 fixers isolated from inside plant tissues and able to grow on PCAT medium, the most abundant isolates belonged to genus Burkholderia (API 20NE, rrs sequences). Representative isolates obtained from roots and shoots of different plants appeared identical (rrs and nifH RFLP), showing that they were closely related. In addition, their 16S rDNA sequences differed from described Burkholderia species and, phylogenetically, they constituted a separate deep-branching new lineage in genus Burkholderia. This indicated that these isolates probably constituted a new species. An inoculation experiment confirmed that these N2-fixing Burkholderia isolates could densely colonize the plant tissues of maize. More isolates of this group were subsequently obtained from field-grown maize and teosinte plants. It was hypothesized that strains of this species had developed a sort of primitive symbiosis with one of their host plants, teosinte, which persisted during the domestication of teosinte into maize.

Burkholderia tropica sp. nov., a novel nitrogen-fixing, plant-associated bacterium

“…nov., relative to other Burkholderia species. Strains Ppe8 T , were closely related, forming a cluster with strains BM16 and BM273 described in a previous study (Estrada et al, 2002), as well as with strain AB98 (Cruz et al, 2001). The similarity among the 16S rRNA gene sequences of these strains ranged from 99?2 to 99?9 %.…”

“…Two isolates from pineapple showed an amplified 16S rDNA restriction analysis (ARDRA) pattern identical to the sugarcane isolate Ppe8 T (Cruz et al, 2001). Recently, the analysis of N 2 -fixing bacteria associated with maize and coffee plants grown under field conditions revealed the presence of B. vietnamiensis, as well as the richness of novel diazotrophic bacterial species belonging to the genus Burkholderia (Estrada-de los Santos et al, 2001;Estrada et al, 2002). These N 2 -fixing isolates exhibited high diversity in the ARDRA profiles.…”

Studies on endophytic Burkholderia sp. from sugarcane and its screening for plant growth promoting potential

“…associated with maize plants cultivated in Mexico by Estrada et al (2002) showed that all the Burkholderia isolates could reduce acetylene…”

Diversidad de bacterias endófitas aisladas de árbol de neem y su actividad inhibitoria contra el Colletotrichum gloesporioides causante de la antracnosis del ñame en el departamento de Sucre

“…De otra parte se ha manifestado que las bacterias endófitas son considerados microorganismos con actividad inhibitoria contra diversos patógenos y la eficiencia de esta actividad según lo han demostrado diversos estudios, es debido a que los microorganismos endófitos pueden establecer una relación mutualista con la planta desde su interior, mediante el cual les confieren protección contra factores bióticos y abióticos adversos (SCHULZ y BOYLE 2006), promueven el crecimiento en las plantas (TSAVKELOVA et al, 2007), aumentan la resistencia a enfermedades (CHANWAY, 1998), contribuyen a la fijación biológica de nitrógeno (JIMENEZ et al, 1997;ESTRADA et al, 2002), bioremediación (NEWMAN Y REYNOLDS, 2005) y producción de sideróforos o inmunidad (SESSITSCH et al, 2002).…”