Improvement of plant growth and seed yield in Jatropha curcas by a novel nitrogen-fixing root associated Enterobacter species

Abstract

BackgroundJatropha curcas L. is an oil seed producing non-leguminous tropical shrub that has good potential to be a fuel plant that can be cultivated on marginal land. Due to the low nutrient content of the targeted plantation area, the requirement for fertilizer is expected to be higher than other plants. This factor severely affects the commercial viability of J. curcas.ResultsWe explored the feasibility to use endophytic nitrogen-fixing bacteria that are native to J. curcas to improve plant growth, biomass and seed productivity. We demonstrated that a novel N-fixing endophyte, Enterobacter sp. R4-368, was able to colonize in root and stem tissues and significantly promoted early plant growth and seed productivity of J. curcas in sterilized and non-sterilized soil. Inoculation of young seedling led to an approximately 57.2% increase in seedling vigour over a six week period. At 90 days after planting, inoculated plants showed an average increase of 25.3%, 77.7%, 27.5%, 45.8% in plant height, leaf number, chlorophyll content and stem volume, respectively. Notably, inoculation of the strain led to a 49.0% increase in the average seed number per plant and 20% increase in the average single seed weight when plants were maintained for 1.5 years in non-sterilized soil in pots in the open air. Enterobacter sp. R4-368 cells were able to colonize root tissues and moved systemically to stem tissues. However, no bacteria were found in leaves. Promotion of plant growth and leaf nitrogen content by the strain was partially lost in nifH, nifD, nifK knockout mutants, suggesting the presence of other growth promoting factors that are associated with this bacterium strain.ConclusionOur results showed that Enterobacter sp. R4-368 significantly promoted growth and seed yield of J. curcas. The application of the strains is likely to significantly improve the commercial viability of J. curcas due to the reduced fertilizer cost and improved oil yield.

Plant growth promoting potential and phylogenetic characteristics of a lichenized nitrogen fixing bacterium, Enterobacter cloacae

“…R4‐368 is an acclaimed potential plant growth promoting bacterium that colonizes J . curcas root and stem tissues . In the present study, as many as eight of the 11 isolates (GSL‐01, ‐02, ‐03, ‐04, ‐05, ‐06, ‐07, and 11) showed maximum similarity with the Enterobacter sp.…”

“…Furthermore, nitrogen fixing Enterobacter sp. from the Jatropha curcas oil seed producing non‐leguminous tropical shrub plant was also reported . However, Enterobacter sp.…”

Isolation and genetic characterization of endophytic and rhizospheric microorganisms from Butia purpurascens Glassman

“…This result is in contrast with the present study, where Bacillus and Enterobacter were found to be the dominant genera of rhizospheric bacteria and Enterobacter was found to be the dominant genus of endophytic bacteria. Madhaiyan et al (2013) studied endophytic bacteria isolated from Jatropha curcas roots from Indonesia, China and India and observed a predominance of strains from genus Enterobacter, such as the species E. oryzae, E. asburiae, E. cancerogenus, E. cloacae, E. aerogenes and E. ludwigii, which were also found in the present study, with several only found in the endophytic environment and others found in both environments.…”

Mecanismos de acción de hongos y bacterias empleados como biofertilizantes en suelos agrícolas: una revisión sistemática

“…Este fenómeno posiblemente se deba a la cantidad y la calidad de los derivados de carbono y las sustancias promotoras provenientes de la raíz, que favorecen el aumento de la biomasa microbiana fijadora de nitrógeno (Ravikumar et al 2004 (Madhaiyan et al 2013). …”