Characterization And Phenotype Analysis Of CrSMT Transgenic Cotton

Cotton is the most vital fiber crop in the world,pathogens and insect herbivores cause up to 10-15% yield losses of cotton.Cotton is also a pioneer crop in the development of saline field,in recent years,cotton was gradually moved to saline areas in order to alleviate issues on deficient fields for cotton and grain crops.It is of great significance to improve its resistance to salt and insects for a high and stable yield.In this study,an upland cotton line R15 was transformed with Cr SMT under the Ca MV 35 S promoter by agrobacterium-mediated transformation,then several positive lines were characterized by PCR,among them,L17 and L25 were further studied,results as follows:(1)RT-PCR and q PCR showed that Cr SMT was expressed in transgenic lines,the relative expression level in L17 was 2.2 times higher than that of L25.GC-MS results showed a significant change in sterol composition,sitosterol decreased significantly while campesterol and stigmasterol increased significantly in L17;sitosterol decreased while campesterol increased significantly in L25.No significant differences were found between wild type and transgenic lines.(2)Spodoptera litura larvae preferred to eat wild type cotton rather than transgenic lines,the generation times of larvae fed on L17 and L25 leaves showed a 5.5 and 4.0 day increase respectively,their survival rate,pupation rate,pupae weight and eclosion rate were significantly lower.The growth and survival rate of Mirid bugs fed on transgenic cotton leaves were lower.Both sensitive and resistant larvae fed on transgenic cotton leaves grew more slowly than those fed on wild type cotton,but no significant differences were found in the mortality.(3)The salt resistant ability was also improved in transgenic cotton,which exhibited a better growth and physiological index than wild type cotton.In summary,we generated cotton lines with resistance to multiple pests and salt stress,which provided new resistant germplasms for multiple stresses.The broad-spectrum and environment-friendly insect resistant strategy could be applied in other plants,especially in grain crops in the future.