Studies On Identification Techniques Of Cotton Varieties With Different Gossypol Contents For Insect Resistance

Cotton is an important economic crop.The identification of insect resistance is an essential link in the cotton breeding process,and plays a key role in the selection and promotion of high quality new cotton varieties.The defense of cotton and the anti defense of insects are important research contents when cotton is interacted with pests.In this process,several functional enzymes play an important role,and the strength of the enzyme activity reflects the insect resistance of cotton.In this experiment,the insect resistance of cotton varieties with different gossypol content was identified.The changes in the activity of peroxidase(POD),superoxide dismutase(SOD)and polyphenol oxidase(PPO)in different cotton varieties before and after the damage of Helicoverpa armigera and Spodoptera exigua were measured.At the same time,the changes of acid phosphatase(ACP),Glutathione-S-transferase(GST)and acetylcholinesterase(AChE)activity of cotton bollworm and beet armyworm were measured and analyzed after feeding different varieties of cotton.To explore and develop methods to assess the resistance of different cotton varieties and to clarify the direction of mining insect resistant genes.The aim was to provide theoretical basis for cotton breeding and identification.The main results of this study are as follows:1.After feeding on cotton for 3 days,the weight of cotton bollworm feeding on low-phenol varieties was higher than that of high-phenol varieties.It can be seen that gossypol has a certain influence on the growth and development of cotton bollworm,and the resistance of high-phenol cotton is stronger than that of low-phenol cotton.2.After feeding on cotton for 3 days,the weight of beet armyworm feeding on low-phenol varieties was higher than that of high-phenol varieties.It can be seen that gossypol has certain influence on the growth and development of beet armyworm.Cotton with high phenol resistance is stronger than cotton with low phenol resistance.3.Under the stress of cotton bollworm feeding,the activity of POD,PPO and SOD was significantly increased,and the POD and PPO activity of low-phenolic cotton was higher than that of phenol cotton.The activity of POD and SOD of cotton increased significantly after the damage of beet armyworm,and the difference of the latter reached significant level.The change of cotton defense enzymes was related to cotton variety,the damage time of gossypol content and insect.The higher the cotton content,the stronger the defense ability of cotton.4.The activity of GST and AChE in Helicoverpa armigera fed on different cotton varieties was affected by gossypol content.High phenol varieties had stronger resistance to cotton bollworm than that of phenolics.The ACP activity of beet armyworm was not only influenced by the cotton variety and the damage time,but also related to the content of gossypol.High phenol varieties had stronger resistance to Spodoptera exigua than that of phenolics.5.Shiyuan 321 was selected as a good parent for breeding a new cotton variety with transgenic bollworm resistance.Lu Mian 12,was selected for breeding transgenic cotton varieties resistant to Spodoptera exigua.In conclusion,gossypol can affect the growth and development of Helicoverpa armigera and Spodoptera exigua,and is related to cotton defense enzymes,insect detoxifying enzymes and acetylcholinesterase.The higher the content of gossypol,the stronger the resistance of cotton to insect resistance.