Sunflower Fungi Research
Improved disease resistance could be in store for tomorrow’s sunflower varieties, thanks to plants that scientists have collected in Australia and are evaluating in greenhouse trials in Fargo, North Dakota. Plant pathologists and botanists collected seeds of wild sunflowers while in Australia in spring 2007. An arm of the Australian government, the Plant Exploration Office, funded their trip. Assisted by their Australian hosts, the plant specialists traveled to every corner of Australia to make 59 collections of Helianthus annuus and H. debilis sunflowers, marking the first time researchers have collected these wild species outside the plants’ native United States.
The ultimate goal is to find new genes that can be incorporated into American sunflower hybrids to make them more resistant to fungi that cause diseases such as downy mildew, rust, and Sclerotinia stalk rot. Each year, outbreaks of stalk rot and other forms of Sclerotinia disease cost about $252 million annually in losses to U.S. sunflower, canola, soybean, and other susceptible crops.
In Australia, however, rust is the bigger menace. There, mild to subtropical climates in areas where sunflowers grow allow the rust fungus, Puccinia helianthi, to skip its winter survival phase and evolve more rapidly via sexual recombination. The result is a far greater diversity of rust races in Australia than those observed in the United States. The plant specialists’ hope is that rust’s nearly year-round presence has prompted a kind of sunflower survival of the fittest, whereby genes from the hardiest Aussie plants could be used to fortify the defenses of their U.S. brethren.
The Term Paper on Viruses, Fungi, Protozoa, Bacteria Info
A virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to bacteria and archaea. Characteristics: Like living organisms, viruses contain nucleic acids and proteins. Inside living cells, viruses can reproduce, but not by the process of mitosis like most living cells. Viruses lack some ...
In fall 2007, the scientists began greenhouse trials of the 59 wild Australian sunflower populations they had collected to evaluate their resistance to downy mildew, which doesn’t currently exist in Australia, and to rust, which is severe there. The sunflower varieties collected in Australia will also be compared with some North American wild sunflower populations for resistance to Sclerotinia stalk rot. Of the three diseases, it is by far the most significant threat to the U.S. crop, so finding new sources of even partial resistance would be a great accomplishment.
Botanists will analyze the Aussie plants’ seed oil content and fatty acid composition, and then compare their genetic profiles to those of American wild sunflowers. This could reveal whether the Australian sunflowers have undergone significant genetic changes since arriving in the Land Down Under more than 100 years ago from America.
Though the scientists are mainly interested in disease resistance, they collected across a broad geographic and climatic range to capture as much genetic diversity as possible. Indeed, their expedition took them on a 6,200-mile journey through West and South Australia, New South Wales, Victoria, and Queensland. On average, their team gathered 6,000 seeds per collection, which included wild populations from yards, hedgerows, vacant lots, sandy beaches, and many municipal garbage dumps, which were among the most productive sites for collecting seed.
Even if new genes for disease resistance aren’t found, the Australian plants seed will be made available to researchers in both the United States and abroad. After testing is complete, the team plans on storing the seed in the Helianthus germplasm collection at the Plant Introduction Station in Ames, Iowa, so that future researchers who might have different research objectives can use this germplasm to find traits in which current projects are not interested.
