eISSN: 2221-6197 DOI: 10.31301/2221-6197

Nodule bacteria in artificial symbioses

Year: 2017

Pages: 356-363

Number: Volume 9, issue 4

Type: scientific article

Summary:

Crop yields depend on many factors, but one of the most important is the availability of nitrogen compounds. The transfer of nitrogen-fixing legume-rhizobia symbiosis to non-legume plants has always been a priority area of research for many scientists working in the field of plant biotechnology. Unfortunately, the simple transfer of genes, involved in the process of nitrogen fixation, has never led to the successful creation of a nitrogen-fixing symbiotic system.

This review briefly describes the achievements made by scientists around the world in the field of creating artificial symbiosis between plants and nodule bacteria. Particular attention is paid to the lectins of legume plants. Lectins are hemagglutinating proteins, which function mainly at the early stages of the formation of legume-rhizobia symbiosis. Transformation of non-legume plants with lectin gene leads to increasing of colonization by rhizobia on the root of transgenic plants. In other words, rhizobia recognize the lectin on the surface of the roots. If rhizobia with fungistatic and growth-stimulating activities is used for colonization, this will lead to the fact that de novo created symbiotic systems will be more resistant to fungal phytopathogens and the plants will be distinguished by large growth parameters, due to the growthstimulating activity of the bacteria.

It is important to review the work devoted to increasing of the competitiveness of rhizobia in symbiotic systems by transforming different genes. Particularly interesting is the increase of copies of the pssA and rosR genes involved in the synthesis of exopolysaccharides. These genes are critical for the formation of biofilms by rhizobia. Biofilms are an important part of biological competition. They help rhizobia to survive in adverse conditions. Another group of genes that is promising from the point of view of obtaining new symbiotic systems are the genes of the Rap proteins. These genes help in attaching rhizobia to the root hairs of plants. Also in this article, little attention is paid to the transformation in order to increase the competitiveness in symbiotic systems of other growth-stimulating gram-negative bacteria, in particular Pseudomonas putida and P. fluorescens.

Keywords:

symbiosis, lectin, rhizobia, agglutinin, adhesin, exopolysaccharide, Nod factor

References:

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eISSN: 2221-6197 DOI: 10.31301/2221-6197