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Brazilian leadership

Publication of the Agrobacterium genome strengthens Brazilian bio-information technology

The race was a difficult one. With the rearguard of the Bio-Information Technology Laboratory (LBI) of the State University of Campinas (Unicamp), University of Washington has concluded the sequencing of the genome of one of the bacteria most used in the production of transgenic plants, Agrobacterium tumefaciens. The scientific article with the results came out in the December 14th edition of Science magazine, and was followed by another, signed by researchers from Cereon Genomics, a Monsanto subsidiary, with another version of the same genome.

Science gave the cover story to the sequencing of the C58 lineage of A. tumefaciens, which, according to the article commented on in the magazine itself, should give a new impulse to research into biotechnology. Agrobacterium shows a natural ability for transferring part of its DNA to plants, whose genome then comes to express the genes received. In about 600 species of plants, including roses and vines, the bacterium causes a kind of plant cancer, the crown gall: the disorderly growth of the cells causes galls (tumors) at the joint between the trunk and the root (crown), or in the root itself.

The knowledge of the structure of the DNA (deoxyribonucleic acid, which contains the genetic code) of the microorganism should elucidate its mechanism for action, exploited since the eighties to insert genetic material into farm crops.”We did not think that it would come out in Science, because the data had already been disclosed to the GenBank”, says João Paulo Kitajima, one of the coordinators of the LBI, connected with the ONSA (Organization for the Analysis and Sequencing of Nucleotides) network, created by FAPESP. João Carlos Setúbal, another of the LBI’s coordinators, worked for a year and a half as a visiting professor at Washington University, close to the biologists who were looking after the mapping of the Agrobacterium.

The bio-information specialists from São Paulo did the most sophisticated part of the job, the annotation of the genome (the interpretation of data and identification of genes), besides setting up the project’s database, which is to be found on a website maintained by Unicamp. Also taking part was a researcher from the Federal University of Mato Grosso do Sul, Nalvo Almeida Jr., who compared the Agrobacterium‘s genome with that of other bacteria.

Working separately, the team from Washington University, made up as well by members from the DuPont company and from Cereon, in conjunction with Richmond University and Hiram College, reached similar results. The microorganism’s genome has about 5.6 million base pairs and a little more than 5,000 genes (5,419 for the Washington group, and 5,299 for the Cereon team). The genetic material is contained in two chromosomes, one circular and one linear, and in two smaller pieces of DNA, the plasmids. In the article published in Science, the team from Washington points out that A. tumefaciens must have a common ancestor with Sinorhizobium meliloti, a bacterium that also lives in the ground but which does not cause disease: the circular chromosome of the two of them is very similar.

The challenge now is to understand how they became differentiated, in the course of evolution. Cereon’s researchers discovered that Agrobacterium does not have the genes normally used by other organisms to infect the host – a sign that the bacterium must use other parts of the DNA for this task.