Bacteria of the genus Agrobacterium and their importance in biotechnology

Abstract

Zelena biotehnologija bavi se uporabom ekološki prihvatljivih rješenja kao alternativa tradicionalnoj poljoprivredi te na taj način nastoji smanjiti ovisnost poljoprivrede o mehaničkim i kemijskim inovacijama. Primjer zelene biotehnologije je proizvodnja transgenih biljaka uz pomoć mikroorganizama kao što su to agrobakterije. Rod Agrobacterium obuhvaća Gram-negativne mikroorganizme koji su poznati po svojoj patogenosti. Naime, vrste ovoga roda posjeduju Ti-plazmid uz pomoć kojeg stvaraju tumore vrata korijena ili Ri plazmid koji uzrokuje pojačani rast korijenovih dlačica. Infekcija nastaje preko ozljede biljke, nakon čega dolazi do transformacije biljnih stanica u tumorne stanice koje se dalje samostalno razmnožavaju. Svrha infekcije je da agrobakterija kontrolira mehanizme domaćina za sintezu nekih esencijalnih metabolita za vlastiti rast. Jedinstvenost roda Agrobacterium leži u mogućnosti genetske transformacije domaćina prenošenjem dobro definiranog segmenta DNA iz Ti-plazmida u genom stanice domaćina. Regija T-DNA je mobilni element koji je odgovoran za stvaranje tumora i biosintezu opina u biljci. Kako bi postali pogodni za uporabu u biotehnologiji, nekada korišteni sojevi Agrobacterium trebali su biti konstruirani od odabranih sojeva divljeg tipa. Neke prirodne značajke Ti-plazmida morale su se u potpunosti ukloniti (npr. geni odgovorni za stvaranje tumora), dok su karakteristike nekih komponenata mehanizama za transformaciju morale biti poboljšane. Uz poboljšane karakteristike Ti-plazmida vrste roda Agrobacterium postale su pogodne za izradu vektora, čime se mogu dobiti transgene biljke koje su rezistentne na štetočine, tolerantne na herbicide, te imaju poboljšani nutritivni sastav.Green biotechnology deals with the use of environmentally-friendly solutions as an alternative to traditional agriculture and in that way seeks to reduce the dependence of agriculture on mechanical and chemical innovations. An example of green biotechnology is the production of transgenic plants with the help of microorganisms such as agrobacteria. The genus Agrobacterium includes Gram-negative microorganisms that are known for their pathogenicity. Moreover, species of this genus possess Ti-plasmid which causes crown gall or Ri-plasmid which causes increased growth of root hairs. Infection occurs through injury to the plant, followed by the transformation of plant cells into tumor cells that further proliferate independently. The purpose of infection is for the agrobacterium to control host mechanisms for the synthesis of some essential metabolites for its own growth. Uniqueness of the genus Agrobacterium lies in the possibility of genetic transformation of the host by transferring a well-defined segment of DNA from the Ti-plasmid into the genome of the host cell. The T-DNA region is the mobile element responsible for tumor formation and opin biosynthesis in the plant. To become suitable for use in biotechnology, once-used Agrobacterium strains had to be constructed from selected wild-type strains. Some natural features of Ti-plasmids had to be completely removed (e.g. genes responsible for tumor formation), while the characteristics of some components of the transformation mechanisms had to be improved. With the improved characteristics of Ti-plasmids species of the genus Agrobacterium have become suitable for vector construction, which can provide transgenic plants that are resistant to pests, tolerant to herbicides, and have improved nutritional composition