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Science & Technology » Agriculture Share

Herbicide-resistant 'superweeds' and GM crops

Herbicide-resistant 'superweeds' and GM crops

New Delhi, Dec 1 (UNI) Herbicide-resistant "superweeds" change their mating strategies over time, an evolutionary shift that helps them hold onto valuable genes and outcompete other plants, including genetically modified (GM) herbicide-resistant crops, according to a new study from University of Michigan.
The study examined the relationships between plant mating systems (fertilization) and herbicide resistance in the common agricultural weed morning glory.
The researchers found that morning glory populations that have evolved resistance to the herbicide Roundup rely on self-fertilization more than susceptible populations do.
The increased reliance on self-fertilization may help perpetuate Roundup resistance by blocking the flow herbicide-susceptibility genes from other plants, the researchers concluded.
The results highlight the potential unforeseen consequences of human activities - in this case the widespread use of Roundup Ready crops, which are genetically modified to tolerate the herbicide - on wild plants such as weeds.
"We need to fully understand how we are altering plant species through the use of agricultural chemicals (and) the kind of evolution are we causing due to impacts that we didn't quite foresee?" says plant ecological geneticist Regina Baucom, senior author of a paper published online in the journal Ecology Letters.
"This is further evidence that human activities can have unintended impacts on plant populations, in this case changes in traits that we weren't necessarily anticipating might evolve," said Baucom, an assistant professor in the Department of Ecology and Evolutionary Biology.
Baucom's team, which includes Shu-Mei Chang of the University of Georgia, sampled 32 morning glory populations growing in and around GM corn and GM soybean fields in the US Midwest and Southeast.
Morning glories in agricultural fields have been consistently exposed to glyphosate, the active ingredient in the herbicide Roundup, since Roundup Ready GM crops were widely adopted in the United States in the late 1990s.
Baucom's team had previously shown that this colourful flowering weed has developed varying levels of resistance to glyphosate across its North American range.
Morning glory is a mixed-mating species, meaning that individual flowers can reproduce either by self-fertilization, which is known as selfing, or by using pollen from another individual, a process called outcrossing.
Morning glories are hermaphroditic: Each flower has both male and female reproductive parts.
In self-fertilization, pollen grains formed in the male part, the anther, are shared with the stigma, the female structure inside the flower that receives pollen.
In the Ecology Letters paper, Baucom and her colleagues show that herbicide-resistant morning glory populations self-fertilize more than herbicide-susceptible populations.
The researchers also show that in the most-resistant morning glory populations, the distance between the anther and stigma is the smallest, a trait previously shown by Chang to increase self-fertilization in this species.
The increased reliance on self-fertilization and the shrinking anther-stigma distance both have the effect of perpetuating resistance genes by blocking the influx of herbicide-susceptibility genes from other plants.
"We are the first to show that the mating system of an agricultural weed is correlated to the level of herbicide resistance - the more highly resistant populations are also more selfing," Baucom said.
"In addition, we believe we have identified a physical mechanism that may allow plants to hold onto resistance genes through higher selfing.
" In the United States, 40 per cent of the pesticides applied across 400 million acres of cropland are herbicides.
Worldwide, herbicide resistance has evolved in more than 200 plant species.
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Panacea

Panacea Biotec receives Manufacturing Authorisation for 22 medicinal products

Mumbai, Oct 17 (UNI)Panacea Biotec a leading biotechnology company said that it has received the Certificate of GMP Compliance from State Service of Ukraine on Medicines and Drugs Control with Manufacturing Authorization for 22 medicinal products, including 4 oncology products for a period valid till June 24, 2020.

UN

UN launches plan to stop transmission of bovine TB to humans

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World

World will have more obese children and adolescents than underweight by 2022: WHO

Kolkata, Oct 12 (UNI) The number of obese children and adolescents (aged five to 19 years) worldwide has risen tenfold in the past four decades.

Int'l

Int'l breast cancer conference stresses on need for early diagnosis, awareness

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Kidney

Kidney transplant saves life of in-house patient

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Solar eclipse 2017: North America will witness total solar eclipse

Solar eclipse 2017: North America will witness total solar eclipse

New York, Aug 21 (UNI) Today, all of North America will witness a total solar eclipse for the first time in 99 years, where the Moon will pass in front of the Sun, casting darkness across swathes of the Earth's surface - with up to 14 states shrouded in complete blackout.

Nano-particle fertilizer could lead to new 'green revolution'

Nano-particle fertilizer could lead to new 'green revolution'

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Broken pebbles offer clues to Palaeolithic funeral rituals

Broken pebbles offer clues to Palaeolithic funeral rituals

New Delhi, Feb 9 (UNI) Humans may have ritualistically "killed" objects to remove their symbolic power, some 5,000 years earlier than previously thought, a new international study of marine pebble tools from an Upper Palaeolithic burial site in Italy suggests.

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