Weakened Genetic Mechanism of Soybeans is Susceptible for Other Insects

Aphids on leafPertaining to a study conducted at Iowa State University (ISU), a very small insect called Aphid has started to target the Iowa soybeans plants recently; and blocking the crop’s genetic defense against other pests becoming a major threat to the industry.

A journal on Molecular Plant-Microbe Interactions granted by the Iowa Soybean Association (ISA) and the ISU Plant Sciences Institute reveals that Aphids cause malfunctions in the hormonal defense mechanism of the soybeans. The study also exhibits that this phenomenon paves the way for other pests including the soybean cyst nematode (SCN) to infest the plant simultaneously.

Gustavo MacIntosh, co-writer of the journal and an ISU associate professor in the Roy J. Carver Department of Biophysics, Biochemistry, and Molecular Biology says, “The plant’s immune system goes unresponsive in one week after the Aphid’s infestation. The soybean plant fights against the infection initially, but in a course of seven days, the strength of defense mechanism gradually tapers off to nil. MacIntosh coauthored the journal with Matthew Studham, a student in the ISU Computational Biology and Bioinformatics program.

“In the 2000’s, the Aphid was found to pose serious risks to Iowa soybeans. As a native to Asia, this harmful insect is believed to have accessed the United States through the immigrants and imported plants. Since the year 2000, the Aphid has caused the Iowa soybean formers to suffer from severe reduction, up to 40%, in the overall production of the affected fields,” MacIntosh said.

The farmers need to pour a lot of pesticides into the fields in order to get rid of the Aphid’s presence. This, in turn, increases the production cost. MacIntosh said that the research was primarily focused on to evaluate the changes on the soybean plants, which have undergone a prolonged Aphid infestation.

He added that the soybean plant gets its biological defense ignited once the Aphids initially manage to enter into the system; but eventually in a week or so, the insects infest the plant and make it ‘believe’ that it is under environmental stress. When such situation occurs, the soybean plant undergoes numerous anatomical changes from top to bottom, which is how plants become more prone to getting SCN infection, as explained before in a study conducted by MacIntosh along with Greg Tylka, an ISU professor of plant pathology and microbiology, in the labs of Matt O’Neal, an ISU associate professor of entomology.

Soybean check-off funds from the ISA backed the project; and its publication came out in January. Even soybeans plants that can genetically resist the nematodes infection tends to become more susceptible for the Aphid infestation, Tylka added. Macintosh said that Aphid infestation encourages the nematodes reproduction greatly, but aphid population affects the nematodes negatively.

Macintosh said that this is a bizarre relationship between two pests, which hail from different species; and he believes that the study will help to find out soybean varieties that are more resistant to infestation of Aphids and other insects. Tylka said that MacIntosh’s research might be entertained to predict how the soybeans will react to the new pests in the future. The advancements such as this enable formers to have more steady and profitable soybean production, Tylka added.

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