Further observations on the interaction between sugar cane and Gluconacetobacter diazotrophicus under laboratory and greenhouse conditions1

Abstract

Sugar cane (Saccharum spp.) variety SP 70-1143 was inoculated with Gluconacetobacter diazotrophicus strain PAL5 (ATCC 49037) in two experiments. In experiment 1 the bacteria were inoculated into a modified, low sucrose MS medium within which micropropagated plantlets were rooted. After 10 d there was extensive anatomical evidence of endophytic colonization by G. diazotrophicus, particularly in lower stems, where high numbers of bacteria were visible within some of the xylem vessels. The identity of the bacteria was confirmed by immunogold labelling with an antibody raised against G. diazotrophicus. On the lower stems there were breaks caused by the separation of the plantlets into individuals, and at these 'wounds' bacteria were seen colonizing the xylem and intercellular spaces. Bacteria were also occasionally seen entering leaves via damaged stomata, and subsequently colonizing sub-stomatal cavities and intercellular spaces. A localized host defence response in the form of fibrillar material surrounding the bacteria was associated with both the stem and leaf invasion. In experiment 2, stems of 5-week-old greenhouse-grown plants were inoculated by injection with a suspension of G. diazotrophicus containing 10(8) bacteria ml(-1). No hypersensitive response (HR) was observed, and no symptoms were visible on the leaves and stems for the duration of the experiment (7 d). Close to the point of inoculation, G. diazotrophicus cells were observed within the protoxylem and the xylem parenchyma, where they were surrounded by fibrillar material that stained light-green with toluidine blue. In leaf samples taken up to 4 cm from the inoculation points, G. diazotrophicus cells were mainly found within the metaxylem, where they were surrounded by a light green-staining material. The bacteria were growing in relatively low numbers adjacent to the xylem cell walls, and they were separated from the host-derived material by electron-transparent 'haloes' that contained material that reacted with the G. diazotrophicus antibody.

Endophytic Colonization of Vitis vinifera L. by Plant Growth-Promoting Bacterium Burkholderia sp. Strain PsJN

“…Several studies have shown that endophytic populations of strains of various nonpathogenic bacterial species cannot become established following infiltration into leaves (48,69). To our knowledge, only James et al (21,23) have reported colonization of substomatal chambers by plantbeneficial bacteria, but there was the possibility of epiphytic bacterial propagation on the phylloplane (21,23) and/or spreading within the plant (23). Our finding of PsJN cells in substomatal chambers after an initial root colonization step confirmed that substomatal chambers can be colonized by bacteria after they spread within the plant.…”

History on the biological nitrogen fixation research in graminaceous plants: special emphasis on the Brazilian experience

“…The bacteria are able to infect and colonize the root tissues and aerial parts by penetrating root tip and lateral roots formed during the rooting process (James et al 1994). At the colm base, where the tissues are heavily colonized, the bacteria move to the aerial part using the xylematic vessels (James et al 1994(James et al , 2001. Relatively large populations of the bacteria are found in these tissues, suggesting that this is one of the main sites for nitrogen fixation due to the low oxygen level and the energy available in form of sucrose for nitrogen fixation (James et al 1994).…”

In silico differential display of defense-related expressed sequence tags from sugarcane tissues infected with diazotrophic endophytes

“…Accumulation of polysaccharides and tannins in the parenchyma cells around the metaxylem of sugarcane clone Ja60-5 inoculated with Gluconacetobacter diazotrophicus has also been observed, suggesting that the plant defense system is activated during the interaction with the bacterium (Dong et al, 1997). In sugarcane cultivar SP70-1143, no hypersensitive response has been observed after inoculation of leaves and stems with G. diazotrophicus, although an extracellular matrix accumulates around bacterial cells in the protoxylem and xylem parenchyma (James et al, 2001).…”