* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Research lifts early vigour and yields in wheat
Vectors in gene therapy wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Gene therapy wikipedia , lookup
Gene desert wikipedia , lookup
Gene nomenclature wikipedia , lookup
Therapeutic gene modulation wikipedia , lookup
Genome evolution wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Public health genomics wikipedia , lookup
Gene expression programming wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Genetic engineering wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
Gene expression profiling wikipedia , lookup
Genome (book) wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Microevolution wikipedia , lookup
Genetically modified crops wikipedia , lookup
Designer baby wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genetically modified organism containment and escape wikipedia , lookup
Cropping New varieties Research lifts early vigour and yields in wheat Grain growers continually seek new wheat varieties which are better adapted to Australia’s challenging farming systems. Armed with advanced breeding methods and a better understanding of what limits wheat productivity, scientist Wolfgang Spielmeyer details how a CSIRO Plant Industry research team is developing promising new wheat varieties. uture wheat varieties will yield more with less water, compete better with weeds and have higher emergence rates. CSIRO scientists are using molecular marker technology to speed the development of new wheat varieties. By identifying specific markers on wheat chromosomes, researchers can determine quickly whether a newly emerged seedling contains the desired genetic make-up. The marker technology avoids the need to grow plants to maturity before selecting them for desirable traits. Transpiration efficiency Crops with high transpiration efficiency, like the recently released Drysdale wheat variety, yield more with less water. While the method used to measure transpiration efficiency in Drysdale is effective, it is also expensive and unfortunately cannot be automated. To overcome these limitations, CSIRO Plant Industry researchers are developing molecular markers for transpiration efficiency which will hasten the selection of water-efficient wheats in plant breeding programmes significantly. The CSIRO research has shown certain components of high transpiration efficiency are highly heritable and can be tagged with molecular markers. In addition, the molecular marker technology lends itself to automation, potentially enabling hundreds of wheat lines to be screened quickly. At a glance • CSIRO scientists are using advanced genetic methods to produce new wheat varieties. • The new varieties will yield more with less water, compete better with weeds and have higher emergence rates. • Varieties with longer coleoptiles will enable wheat to be sown deeper and earlier in the season. • Reduced tillering varieties will produce larger kernels, reducing the risk of screenings. 40 Photos: CSIRO Plant Industry F Using molecular markers, CSIRO scientists have identified wheat lines which yield more with less water, compete better with weeds and can be sown deeper and earlier without affecting emergence rates. The new varieties will go a long way to meeting the challenges faced by wheat growers, especially in many drier areas. Improving early vigour in wheat Early growth and vigour of wheat is poor compared with other cereals such as barley. Slow growth limits wheat yield in southern Australia. More vigorous wheat varieties would shade the ground faster, reducing evaporation from the soil surface. These varieties would also compete more effectively with weeds and suffer less yield penalty when sown late. Much of the water used by wheat crops in southern and western Australia is provided by in-season rainfall. Yet as much as 50 per cent of this rainfall is lost as water evaporation from the soil — resulting in substantial water loss which, if saved, could be used for crop growth. Weed competition The inability of young wheat plants to outcompete weeds results in reduced yields and consequently more herbicide use. Such high use of herbicides has led to the serious problem of herbicide resistance in some weeds such as ryegrass. CSIRO scientists have identified a marker linked to early vigour located on one of the wheat chromosomes. This discovery is significant because the marker now can be used to hasten the selection of wheat plants with good early vigour. By screening breeding lines for the marker, scientists expect to improve crop establishment of future wheat varieties. Dwarfing genes All wheat varieties released in Australia over the past two decades have short coleoptiles — the sheath encasing the first leaf which pushes the germinating seedling through the soil to reach the surface. Short coleoptiles are an unwanted by-product of certain dwarfing genes in the genetic makeup of wheat. Long-coleoptile wheats containing alternative dwarfing genes are less affected by deep sowing. These varieties produce good stands and higher grain yields than short-coleoptile wheats (for example, Hartog as pictured). FA R M I N G A H E A D No. 150 July 2004 New varieties Cropping FIGURE 1 Tiller inhibition gene reduces tiller numbers to lift yields All Australian wheat varieties produce more tillers than they can sustain until maturity. These superfluous tillers represent a waste of water and nutrients, which otherwise could be invested into grain production. CSIRO scientists have identified a gene responsible for inhibiting tillering and are developing new wheat varieties, which produce larger kernels and consequently reduced screenings. These dwarfing genes are primarily used to reduce plant height — lowering the lodging risk and lifting yields in modern wheats. While the dwarfing genes provide significant yield advantages, the short coleoptiles of modern wheats deter growers from deep sowing at the optimum sowing time because of the risk of reduced seedling emergence and vigour. Instead, sowing is usually delayed until soil moisture increases, forcing growers to accept the likelihood of lower yields. Reduced emergence is worse when seed is sown deep, at higher temperatures or where growth is impeded because of compacted soil. Seedling emergence of current varieties is particularly disadvantaged in minimum tillage as seedlings must emerge through stubble or from hard seed beds. CSIRO scientists have identified alternative dwarfing genes which reduce plant height but do not affect coleoptile length or early vigour. The long-coleoptile wheats containing the alternative dwarfing genes are less affected by deep sowing. These varieties produce good stands and higher grain yields than their shorter coleoptile counterparts. The CSIRO scientists are identifying markers linked to these new dwarfing genes, which will enable the genes to be transferred into new, higher yielding wheat varieties. Tiller number All Australian wheat varieties produce more tillers than they can sustain to grain maturity (see Figure 1). The superfluous tillers represent a waste of water and nutrients which otherwise could be invested into fertile heads to increase grain yield. CSIRO scientists have identified a single gene which reduces tillering known as the FA R M I N G A H E A D No. 150 July 2004 Current varieties Current varieties + tiller inhibition gene (tin) Wasteful tillers Fewer tillers Larger ears Larger grains Source: CSIRO Plant Industry. ‘tin’ gene for tiller inhibition. The process of tillering inhibition is not always complete and it is possible to modify the expression of the tin gene so fewer wasteful tillers are produced. Lines with the tin gene have been yield tested in southern New South Wales over the past three years. Yields have, on average, been similar to the commercial parents but under some conditions yields are higher. In all cases, kernel size has increased, reducing the potential for screenings. A marker linked to the tin gene is being used to select for the presence of this gene in breeding lines. This marker screening is easier than relying on the often complicated scoring procedure of tiller number. For more information contact Wolfgang Spielmeyer wolfgang.spielmeyer@ csiro.au, phone (02) 6246 4934 or fax (02) 6246 5000. What is a molecular marker? olecular marker technology enables scientists to identify the presence of particular genes within plants and animals. M The markers are small pieces of deoxy riboneucleic acid (DNA) located near a gene of interest, for example, a disease resistance gene or a dwarfing gene. The benefit of markers is they can be detected more easily than the expression of the gene they are near. Before marker technology was developed, determining whether a wheat variety contained, for example, a gene for disease resistance involved growing the plant and infecting it with the disease in question. If the plant became diseased, it was identified as not carrying the resistance gene and removed from the plant breeding programme. The process took considerable time and was relatively expensive as resources were spent on identifying unwanted as well as wanted plant varieties. Using molecular markers, scientists can now simply look for the presence of the marker DNA next to the gene in question. The process of marker identification is rapid and relatively inexpensive. More importantly, marker identification can be carried out at any stage during a plant’s development. For example, scientists can test a small piece of seed for the presence of a marker linked to a resistance gene and therefore determine whether the plant will be diseaseresistant without even sowing the seed. Used in this way, thousands of potential new varieties can be tested cheaply and quickly and new varieties can reach their end user years earlier than with traditional plant breeding methods. 41