Environmental Safety Evaluation Of Transgenic Verticillium Wilt Resistant Cotton VdG1

Verticillium dahliae is one of the major diseases that cause cotton yield reduction.It is called"cancer",which is difficult to prevent and control and causes serious economic losses.Researchers from the Chinese Academy of Agricultural Sciences have adopted RNA interference to cultivate Vd G1,a disease-resistant cotton transgenic with Vd GARP1-RNAi gene.Its target microorganism is Verticillium dahliae,which causes the epidemic of cotton verticillium wilt in China.Genetically modified crops need to be evaluated for safety before being popularized and planted,so as to analyze whether they are suitable for planting.Since the variety is genetically modified,its safety to the ecological environment is still uncertain,so it needs to be evaluated for environmental safety.In this study,the environmental safety evaluation of transgenic disease-resistant cotton Vd G1 was studied based on the following five aspects.The results show that:1.Through indoor inoculation and field investigation,the disease resistance of transgenic Verticillium wilt resistant cotton Vd G1 to target diseases and three non-target diseases was evaluated.The results showed that the disease index of transgenic Vd G1 and female parent susceptible varieties were 27.6 and 55.21 respectively,and the disease index of field investigation were 17.97 and 46.17 respectively.After indoor inoculation with cotton fusarium wilt,Rhizoctonia solani and Cotton Boll Blight,the disease index of transgenic Vd G1 was 45.83,63.50 and 55respectively.The disease index of female parent was 38.79,57.29 and 50.83 respectively.Therefore,the resistance of transgenic verticillium wilt resistant cotton Vd G1 to verticillium wilt is significantly higher than that of the female parent,while the resistance to non-target diseases has no difference.2.During the whole growth period of transgenic verticillium wilt-resistant cotton Vd G1,the arthropod community on the cotton field was investigated.The results showed that the arthropod diversity index,evenness index and richness index all reached their peaks on July 2.The peak values of Vd G1 are 1.90,0.96 and 0.80 respectively,and the peak values of female parent are 1.87,0.83 and 0.81 respectively.T test showed that there was no significant difference in diversity index,evenness index and dominance index between transgenic verticillium wilt resistant cotton Vd G1 and its female parent.Compared with female parent,transgenic disease-resistant cotton Vd G1 had no significant effect on arthropod community in cotton field.3.During the whole growth period of transgenic Verticillium dahliae resistant cotton Vd G1,the number of microorganisms in the rhizosphere soil of cotton fields was investigated.The results showed that the number of bacteria in the rhizosphere soil of two cotton fields was the highest at flowering and boll stages,and the number of bacteria in the rhizosphere soil of Vd G1 and female parent cotton fields were 1.8×10~6and 0.8×10~6respectively.The number of fungi in rhizosphere soil was the highest in bud stage,and the number of fungi in Vd G1 and female parent cotton field rhizosphere soil were 4.3×10~3and 3×10~3respectively.The number of actinomycetes in the rhizosphere soil was the highest at harvest time,and the number of actinomycetes in Vd G1 and female parent cotton field rhizosphere soil were 8.2×10~4and 8.7×10~4respectively.The results showed that transgenic disease-resistant cotton Vd G1 had no significant effect on the number of soil microorganisms in cotton fields.4.The pollen morphology,quantity and vitality of transgenic verticillium wilt resistant cotton Vd G1 were measured.The results showed that under the conditions of 25℃,30℃and 35℃,there was no significant difference in the pollen germination rate of transgenic Vd G1cotton and its female parent susceptible varieties under different stimulation duration(p>0.05).There was no significant difference between the pollen morphological indexes of the two cotton species(p>0.05).The morphological indexes of Vd G1 and the female parent were between 0.96 and 0.91.The experimental results proved that the introduction of foreign genes did not affect the shape of cotton pollen.5.The survival competitiveness of transgenic verticillium wilt resistant cotton Vd G1 was studied.The results showed that the emergence rates of Vd G1 and female parent susceptible varieties were 88.6%and 89.2%respectively.The average breeding coefficient was 54 grains/plant and47 grains/plant respectively.Seed germination rates were 78.3%and 70%respectively.The output was 129.84g and 125.62g,respectively.Weed coverage in both cotton fields increased with the extension of cotton growth period.Therefore,transgenic cotton Vd G1 has no obvious growth advantages,no reproductive growth competitive advantages,and no significant breeding coefficient advantages and disadvantages compared with the female parent.To sum up,transgenic disease-resistant cotton Vd G1 has significant resistance to cotton verticillium wilt and has no adverse impact on ecological environment,which is suitable for popularization and planting.In addition,this study provides a relatively sound technical framework for environmental safety evaluation of transgenic disease-resistant cotton Vd G1.