A weed present in Argentina and other parts of the world, it has developed a very high resistance to glyphosate.
A study published in the scientific journal Plant, Cell & Environment shows that Eleusine indicates, known as chicken foot, is capable of resisting 25 times more than the dose recommended by the manufacturers of the herbicide glyphosate due to a particular genetic alteration developed in years of application.
This continued use for decades and the high doses applied in agricultural productions in Malaysia led to the appearance of a second mutation in the gene that gives this weed resistance to glyphosate. The double genetic alteration has a very low probability of occurring naturally: one in a trillion (1 × 10-12). In Argentina and other countries there is also a record of this resistance
What solution do the researchers have?
Plants that develop two mutations do not suffer any alteration or stress when herbicide is applied. It's like watering them with water ”, highlighted Martín Vila Aiub, professor at the Chair of Ecology at the Faculty of Agronomy of the UBA (FAUBA), an independent researcher at Conicet and part of the team of experiments at the University of Western Australia and the Australian Herbicide Resistance Initiative (AHRI) explained: “If the recommended dose of glyphosate is one kilo per hectare, these natural mutants can continue to grow and reproduce even when exposed to 25 kilograms of glyphosate per hectare. In the tests to measure resistance we used that dose as the maximum, but we could have continued observing the same with 30 or 50 kilos per hectare ”. "A resistant mutant appears at a very low frequency, but as after application all the plants die without resistance, in a short time, the batches end up being filled with resistant plants."
The solution that Vila Aiub proposes is: "Giving a break in the use of this herbicide drastically reduces the frequency of this double mutation in batches", that is, if the batch goes to rest, the frequency of this resistance gene would disappear in three or four years.
In any case, for economic reasons, this does not happen among producers who apply larger quantities, change brands and formulas and the problem does not end, on the contrary, there is a greater impact on the environment and higher costs for the producer.
Eleusine indicates It is native to Europe, but has been distributed and naturalized in the agroecosystems of temperate and warm regions of the planet. It is considered a weed in crops such as soybeans, corn, cotton and many others, such as rice, where the double mutation was detected.
Reality proved the opposite of the predictions of 20 years ago
20 years ago, researchers claimed that resistance to glyphosate in weeds was difficult to develop. The reality today proves the opposite. And in the particular case of chicken feet, nature shows that it has ways to evade even stressors as effective as this herbicide. From an evolutionary point of view, the emergence of this resistance is a rare event. “The appearance of a single resistant mutation has a probability of happening of a plant in a million. Meanwhile, the probability that a double mutant will emerge is one in a trillion, since it involves a second mutation in a plant that already has the first. The probabilities are multiplied ”.
In the absence of glyphosate, the double mutant (TIPS) grows much less than the plants with a single mutation that confers resistance (P106S) or without a mutation (Wild type).
The famous glyphosate
The researcher contextualized the glyphosate situation: “It is the most widely used herbicide in world agriculture for weed control for two decades. It can control numerous weeds and is a powerful inhibitor of a metabolism only present in plants and bacteria ”.
“The appearance of resistance in weeds can occur with any other herbicide that is applied continuously. Until a while ago it was not noticed on the labels, but recently in our country, the company that manufactures the product began to warn on the label the possibility of resistance being generated ”, he closed.