A new breed of giant tumbleweed predicted to die will not only stay here, but probably expand its territory.
The species, Salsola ryanii is significantly larger than any of their parent plants, which can grow up to 6 feet tall. A new study by UC Riverside confirms the theory that the new water spill is growing faster because it is a hybrid with double pairs of their parents' chromosomes.
The results of the study were published in a new Oxford University Journal AoB Plants .
" Salsola ryanii is a malicious species that replaces other malignant tumbleweed species in the US," said the co-author of the study, Norman Ellstrand, UCR Distinguished Professor of Genetics. "It's healthier than previous versions, and now we know why."
Humans are diploid organisms, with one set of chromosomes donated by the mother and one set by the father. Sometimes a mother's house contains more than two sets of chromosomes than just the one it's supposed to pass on. If this egg is fertilized, the offspring would be threefold with three sets of chromosomes. Most people do not survive this.
Plants with parents closely related to mating may produce triploid progeny that survive but can not reproduce themselves. However, a hybrid plant that manages to get two copies from the mother and two from the father will be fruitful. Some species may have more than four sets of chromosomes. You may even have hexaploidy with six sets of chromosomes.
Scientists have long assumed that polyploidy must have an evolutionary advantage, the term for hybrids with multiple sets of chromosomes, since it brings some immediate difficulties with the new hybrids.
"If something is new and it is the only one of its kind, it's a downside, there's no one with whom to mate," said study author Shana Welles, a graduate student in Ellstrand's lab, who led the study in the As part of her doctorate carried out research. She is now a postdoctoral fellow at Chapman University.
According to the study, the advantage of several sets of chromosomes is that the hybrid plant grows more vigorously than the parent. This has been suggested because polyploidy is so common in plants. However, it has not been demonstrated experimentally.
Polyploidy is associated with our favorite crops; domesticated peanuts have four sets of chromosomes and the wheat we eat six.
Although tumbleweeds are often regarded as symbols of the ancient West of America, they are also invasive plants that cause traffic accidents, damage agricultural businesses and cause millions of property damage each year. Last year they buried the desert town of Victorville, California, which dates back to the second story of some homes.
Currently Salsola ryanii has a relatively small but expanding geographic reach. With the new study stating that it is even stronger than its ancestors, which are invasive in 48 states, Welles said it is likely to expand its range further. In addition, Welles said climate change could boost territorial takeover.
Although this water spill is one-year old, it tends to grow later in the winter.
"It's one of the few things that are still green in late summer." Welles said. "They may be well positioned to take advantage of the summer rainfall as climate change spreads it."
Given its potential for harm, the now available knowledge of Salsola ryanii may be important in contributing to the suppression, and Ellstrand believes this should happen before taking power.
"An ounce of prevention is a pound of cure," he said.
New tumbleweed species are expanding rapidly
Shana Welles et al., Evolution of increased vitality associated with allopolyploidization in the newly formed invasive species Salsolaryanii, AoB PLANTS (2019). DOI: 10.1093 / aobpla / plz039
Monster Tumbleweed: Invasive New Species Stay Here (2019, Aug 26)
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