Trials to create artificial nitrogen-fixing symbioses and associations using in vitro methods: An outlook

Abstract

Biological nitrogen fixation is the most important process in which some prokaryotic organisms fix N 2 into ammonium. From an agricultural standpoint, biological nitrogen fixation (BNF) is critical because industrial production of nitrogen fertilizers seldom meets agricultural demands. To increase the BNF is one of the main challenges for the future. There are different possibilities for extending biological nitrogen fixation to the economically important plants. One of the possibilities is to create new artificial systems between diazotrophic bacteria and different higher plants. This is the main topic of the present review article which discusses the establishment of new associative and/or symbiotic systems, via introduction of diazotrophic bacteria into the roots by different methods; and incorporation of nitrogen-fixing bacteria in the entire plant by in vitro methods, through the establishment of intracellular endosymbioses via induced uptake of bacteria by plant protoplasts (endocytobiosis), and establishment of intercellular associations by forced introduction of bacteria into the plant tissues (exocytobiosis). The common characteristic of the methods to create artificial plant±microbe systems for atmospheric nitrogen fixation is the use of in vitro plant systems: cells, tissues and organ cultures. The review pays particular attention to new bacterial inoculation procedures for introduction of the diazotrophic bacteria inside the plant tissues.

Resposta de plantas micropropagadas de abacaxizeiro à inoculação de bactérias diazotróficas em casa de vegetação

“…Considerando os benefícios na aclimatação das plantas (Tabelas 2 a 4), sugere-se realizar trabalhos em campo, a fim de sugerir a aplicação da tecnologia. Em outras culturas tem-se sugerido o estabelecimento da associação simbiótica com bactérias fixadoras de nitrogênio (Preininger & Gyrlján, 2001). …”

“…Recentemente, bactérias diazotróficas têm sido isoladas de abacaxizeiros (Weber et al, 1999;Tapia-Henández et al, 2000), e de várias outras culturas (Reis et al, 2000). O estabelecimento artificial da associação simbiótica de plantas não leguminosas com bactérias fixadoras de nitrogênio foi sugerido por Preininger & Gyrlján (2001). Plantas de abacaxizeiros da cultivar Cayenne Champac podem beneficiar-se da associação com bactérias diazotróficas pertencentes a espécie Asaia bogorensis e, após quatro meses de aclimatação, as plantas estão aptas para o transplante no campo (Weber et al, 2003).…”

Developing microbe–plant interactions for applications in plant‐growth promotion and disease control, production of useful compounds, remediation and carbon sequestration

“…Frankia ) provide most of the nitrogen (N) available to legumes and actinorhizal plant species. A number of studies attempted to develop new association between non‐legume plants and N‐fixing bacteria; however, these attempts were mostly unsuccessful ( Preininger and Gyurjan, 2001 ). The discovery of endophytic diazotrophs that provided reduced N to the non‐legume plant species represents an alternative way of exploiting plant–microbe interaction for N nutrition.…”