Ground Cover North : Ground Cover 049 April-May 2004 - North
NEWS 5 APRIL 2004 GENE TECHNOLOGY By BRAD COLLIS A room full of white-frocked technicians bent studiously over microscopes and petri dishes; creamy tendrils of plant DNA looped between vials and pipettes – a normal enough scene in a plant breeding laboratory, except for one thing. Most of these ‘scientists’ are graingrowers. In a few hours they have progressed from a PowerPoint presentation of plant cells, to using microscopes to identify for themselves a plant’s cell structure, and then actually extracting DNA. On this, just the frst morning of a two-day workshop on gene technology, the veil of mystery and unease that often shrouds the work of plant geneticists is lifted to reveal a surprisingly simple, mechanical process. The main ‘high-tech’ tools used to extract DNA, from which a breeder would later take the genes being sought to create a new, improved crop variety, are a coffee grinder, bench-top centrifuge, and a few beakers of detergent and alcohol. A handful of kidney beans are ground in the coffee grinder, then mixed in water and detergent which further breaks down the cracked cell membranes. The slurry is poured into test tubes which are given several minutes in the centrifuge to separate liquid from solids. A few more detergent washes follow, which completely break down the membrane around the cells’ nuclei, releasing the DNA that fnally appears as milky bands suspended in a clear liquid. It took Nobel Prize-winning science to work all this out 50 years ago, but now it is done by primary school students, who occasionally do the same course as these growers. The Gene Technology Workshops are run by CSIRO Industry Link, Agrifood Awareness Australia and Partners in Grain, to give farmers, and others, some hands-on experience in the basics of genetic engineering. The workshops cover the actual science, as well as discussions on risks, opportunities and the role of regulation. Paula Fitzgerald, executive manager of Agrifood Awareness, says the workshops have been designed to simply provide growers with factual knowledge about the science behind gene technology to help them with their own decision-making on the issue. “The feedback we get shows growers are much more confdent about entering the debate about GM crops once they’ve done the course. The two-day interaction also makes them more ready to contact us or CSIRO whenever they want more information.” On this recent workshop, prominent plant biotechnologist Dr T.J. Higgins highlighted one drawback of conventional plant-breeding by relating the experience of plant breeders when they sought to use the rust resistance in rye to breed a rust-resistant wheat. “The only rye gene the breeders wanted was the rust-resistance gene, but in conventional plant breeding you begin with half the genes of one parent and half the genes of the other, and then spend the next 10 to 15 years back-crossing to try and eliminate the unwanted genes. “Even then you are still left with hundreds of unknown genes, and in the case of the wheat variety which did eventually carry rye’s rust resistance, these lingering rye genes created a ‘sticky dough’ which gummed up dough-mixing machines. “By contrast, gene technology would allow the modern breeder to only take the rust- resistance gene.” Growers were shown how the extraction of the genes is also, basically, a mechanical process, albeit using a molecular toolkit. Genes can be cut from the DNA of one plant and ‘spliced’ into the DNA of another plant using specifc enzymes. These Restriction Enzymes, or ‘DNA scissors’ were discovered about 30 years ago during research into bacteria. Bacteria use the enzymes to defend themselves against viruses by ‘surgically’ removing the gene posing the threat. Scientists then discovered that viruses were able to counter-attack by ‘re-glueing’ their DNA together again; giving human science a microbial tool with which to cut and splice genes in DNA strands and create what is termed recombinant (recombined) DNA. About 200 Restriction Enzymes and the specifc DNA codes where they cut, have so far been discovered. The CSIRO runs about 10 Gene Technology Workshops a year, depending on demand, and has plans to take the workshops around the country. For more information: Details on the workshops can be obtained from CSIRO Industry Link on 02 6246 5469 or firstname.lastname@example.org. Hands-on: Sharon Taylor, an adviser with the Central West Farming Systems grower group in NSW, learns how to extract plant DNA in the workshop. Ms Taylor says she wanted to better understand the processes. Growers go to the lab to discover how GM works ��� ���� ����� ����� ���� ��� ���� ����� ������������������������� ���� ���� ��� ���� ������ ����� ��� �� ������� ����� ����� ������ ���� �������� �� ��� ��������� �� ��� ������� �������� ����� ������ ������ �������� ��������� ��� ������ ������� �������� ������� ������� ��������� ��� ���������� ������ ���� ������� ����� ���� �� ��� ����� �� ����� ��� ������������ ��������� ��� �������� ������������ ��� �������� ������ ���� �������� �� ��������� ��� ���������� �� ������������ ���� ��������� �� �� ���� ������� ���� ������� ������ ���� �� �������� ������� ������� ��������� ������� ��� �������� ����������� ��������� ������ ���� �������� ������� ��� � ���������������� ������������ ������� ���� ������������ ���� ��������� ���������� ����� ������� ������ ������� �� ���� ���� �� ���� ��� ��� ��� ���� ������������ �������� ������������������������ An Australian-owned technology has been developed by which male sterility in plants such as canola can be regulated for the production of new high-yielding hybrids year- after-year. A hybrid variety will generally out-yield open pollinated varieties because of the phenomenon known as ‘hybrid vigour’ but this drops away in the next generation. The lure for plant breeders has been the concept of gaining the benefts of hybrid vigour every season, by controlling the pollination process – and this is what has been achieved by a La Trobe University team led by Professor Roger Parish. Assuming a moderate 50 percent adoption and 10 percent increase in yield, Professor Parish believes the system should add about $30 million to the Australian canola crop. This is a conservative estimate, as the usual yield increase from hybridisation is up to 25 percent. The key to the La Trobe team’s achievement is its identifcation of the genes responsible for ‘turning on’ pollen production, and its discovery of a way to then stop the production. “We isolated three master switches responsible for pollen production and found that by inserting a small piece of canola DNA into the plant we could stop their action,” explains Professor Parish. “The technology is designed so that when the fowers are sprayed with a simple chemical, the master switch genes are turned off. “Pollen sacs are produced but they’re empty, and since the DNA used comes from the plant itself we’re not using any ‘foreign’ genes.” In effect, the technology is blocking pollen production in one line – by chemically inducing male sterility – guaranteeing pollination by an adjacent plant of a related line. Professor Parish says that only the seed producer will need to spray a crop to reverse the action of the genetic modifcation: “Commercial growers will simply buy seed from a registered grower and treat it as a normal crop.” Since the canola breakthrough, Professor Parish has also discovered similar genes in wheat, rice and barley and believes the same technology could be applied to those crops. The rights to the technology, which is attracting international attention, are largely owned by Australian growers through the GRDC. GRDC RESEARCH CODE ULA46, program 2 For more information: Roger Parish 03 9479 2228, email@example.com Making hybrids keep their vigour S S S R R R S S R X BC BC BC B B B GENE CONSTRUCT FOR WEEVIL RESISTANCE IN PEA SEEDS PLANT BREEDING GENE TECHNOLOGY Seed gene from pea Insect resistance gene from bean CONTROL CODING CONTROL CONTROL CODING CONTROL Bean insect resistance code for protein with attached DNA control switches for activity in pea seeds Hundreds of extra genes together g with resistance w(R) gene Single gene R R An example of cutting a desired gene from the DNA of one plant and ‘splicing’ it into the DNA of another, in this instance the gene that gives bean resistance to weevils is inserted into a space created in the DNA coding of a pea plant. Conventional plant breeding introduces hundreds of genes in addition to the wanted l l l l l l l l l l l l l l l gene. Gene technology offers far greater control by bringing in only the targeted gene.
Ground Cover 050 June-July 2004 - North
Ground Cover 048 February-March 2004 - North