Development Of New Strategies For Insect Resistant Transgenic Crops

With the rapid development of biotechnology, research on Bt is no longer limited to isolation, identification, production and fermentation of strains. In 1981, scientists isolated the first cry gene encoding insecticidal crystal protein. By the end of 2015, 813 Bt genes had been reported.

Since the mid-1980s, based on the clear insect killing mechanism and wide application of Bt protein, scientists have proposed to use plant genetic engineering to carry out insect resistant transgenic breeding, and directly transfer Bt gene into plant cells, which is like vaccinating plants, so that plants can obtain the ability to resist insect pests.

Among Bt crops, insect resistant cotton is the most effective and widely used. Cotton production is seriously harmed by pests. Cotton bollworm is one of the natural enemies of cotton. Once cotton is harmed, the plant will turn yellow, wither, or even fail to blossom and open bolls, resulting in reduced yield of cotton fields and reduced income of cotton farmers.

In the early days, people mainly used chemical pesticides to control cotton bollworm, but long-term use would make pests resistant, and pesticides were harmful to human body, easy to be poisoned, and would also cause serious pollution to the environment.

In 1987, Agracetus reported for the first time that foreign Bt insecticidal protein gene was transferred into cotton.

In 1990, Monsanto transferred BtCrylA gene into Kezi 312 cotton. After further research and improvement, it successfully bred several BtCrylA transgenic cotton varieties and finally planted them in large areas.

In 1997, the United States planted more than 1 million hectares of insect resistant cotton, with an average increase of 7%. China is the second country in the world to cultivate insect resistant cotton after the United States. The application of insect resistant cotton has spread all over the country and has completely replaced imported varieties.

Years of field experiments have shown that transgenic cotton has reduced the use of chemical pesticides such as cotton pesticides by 40-60%. Chemical pesticides have greatly reduced the pollution to the environment, and also reduced the occurrence of human and animal poisoning incidents. At the same time, it has also reduced the pollution of pesticides to intercropped crops with cotton, improved the safety of these crops, which is more conducive to three-dimensional cotton planting, Reduce cotton planting cost, increase benefits and form a virtuous circle.

So far, in addition to cotton, corn, rice and other common field crops, the Bt gene has also been successfully transferred into potato, tomato, poplar and other crops and trees.

The genes with insect resistance are not limited to cry series genes in Bt. Scientists also found other insect resistance genes. In addition, scientists are working on new strategies for transgenic insect resistant crops. German scientists developed RNA interference strategy. The insect resistant transgenic potato produced by this strategy did not transfer foreign protein, but only transferred a double stranded RNA into chloroplast or other plastids, which can specifically interfere with different genes of different pests and affect the growth and development of pests.

At present, it has been tested on cotton, corn, rice, soybean, potato, tomato, tobacco, grape, rape, beet, sunflower and other crops.