By adding these new genes, the plant will express the traits associated with the genes. For example, you can apply genes that express a protein that kills insects. 

(” The Organic & Non-GMO Report")

 

-Insects are becoming resistant to crops that have been genetically modified to produce their own insecticides.

Studies found that more than the 1/3 of the major pest species had become immune to GMO corn and cotton. 

 

-The center for food safety states the environmental impacts of GMO will include an uncontrolled biological pollution, threatening numerous microbial, plant and animal species with extinction, and a potential contamination of all non-genetically engineered life forms.

(“GMO Risks.” GMO Awareness)

 

They are using a technique altering the existing banana DNA.

"Good science can make a massive difference here by enriching staple crops such as Ugandan bananas with pro-vitamin A and providing poor and subsistence-farming populations with nutritionally rewarding food," said project leader Professor James Dale.

Scientists in Australia have created golden-orange-fleshed bananas rich in pro-vitamin A that could save lots of lives.

 

These bananas are developed by taking genes from a species of banana from Papua New Guinea, which is high in provitamin A but only produces small bunches, and combined it with a Cavendish banana, the species most people are familiar with.

(The Guardian, Guardian News and Media)

“Where Are GMOs Grown and Banned? #GMOFAQ.” GMO FAQ, gmo.geneticliteracyproject.org/FAQ/where-are-gmos-grown-and-banned/.

“The Environmental Impact of GMOs.” One Green Planet, 19 Feb. 2018, www.onegreenplanet.org/animalsandnature/the-environmental-impact-of-gmos/.

First of all, GMOs can be toxic for some animals and insects like bees or butterflies. They are important in the pollination of crops so we can't take the risk of killing them.

Also, GMO will not always be effective, but their toxic legacies will remain.

Another problem, could be the modified plants, they can become invasive species in some natural ecosystems. They can become persistent and weedy in agricultural conditions.

Lastly, GMO put at risk all ecosystems and biodiversity. The nature of GMOs will cause fewer weed flowers and less nectar for pollinators.

In addition, it can carrie problems into water sources and into the air. This exposes different bacteria, insects, and animals to the same factors.

(“The Environmental Impact of GMOs.” One Green Planet)