Study On Neutralizing Fungal Mycotoxin Deoxynivalenol By Plantibody And Resistance Against Wheat Scab

Fusarium head blight or wheat scab,caused by Fusarium graminearum(teleo-morph Gibberella zeae(Schew)Petch),is one of the most important diseases of wheat,barley and corn in China. Head blight not only causes the severe loss of grain yield,but also causes the harvested grain contaminated with several mycotoxin,such as deoxynivalenol(DON).The consumption of food product made from grains contaminated with the toxin DON is a potential healthy problem for human and farm animals,which is known to cause carcinogenic,genotoxic acute or chronic diseases and to directly target the kidney,liver or immune system. So it is very important to study how to neutralize the mycotoxin DON so as to alliveate the severity of wheat scab.Researchers has achieved great progress in the study of plantibody since a decade years ago.There has been many studies about plantibody since Hiatt first testified antibody protein could be expressed and assemblied in plants.With the development of antibody engeering,it has been reported the scFvs(single chain variable fragment) are expressed in many kinds of plants, and it can specially resist against some plant pathogens.This study takes aim at neutralizing the toxicity of DON, alliveating the severity of wheat scab and exploring a new pathway of resistance against wheat scab.In this paper, the DONscFv gene was cloned,transferred and expressed in tobacoo plants,and we studied that the scFv functioned to neutralize the toxicity of DON.The study showed that the seeds of transgenic tobacoo lines were more tolerant than wild type when they germinated in the MS media containing 8μM/L DON.Moreover,we constructed the expression vector used in wheat plant,and we got transgenic wheat plants by Agrobacterium-mediated method. The transformed plants were screened by PCR and ELISA for the presence and expression of the scFv, respectively.And we got four transgenic To plants.We used T transgenic wheat plants to indentify the resistance against wheat scab by inoculating Fusarium spores. The wild types showed typical symptoms of wheat head scab,while most of the transgenic T plants showed less symptoms 8 days after inoculation. But the transgenic T plants show as typical symptoms as the wild types 10 days after inoculation.These results showed that, in inoculating experiment, transgenic wheat plants only delayed symptoms of wheat head scab to some extent,for DON play a key role in symptom development as well as in pathogen spreading within host tissues, and the scFv expressed in transgenic wheat plants may neutralize the mycotocity of DON,induced by Fusarium metabolizing.Moreover,because there are few studies on the regeneration system of wheat mature embryos.We also used wheat variety JM 2148 mature embryos as explants to study the regeneration. Moreover,we transferred GUS gene into JM 2148 mature embryos by particle bombardment so as to establish the transformational system of mature embryos by particle bombardment.The results indicated that it is a pratical way for using the wheat mature embryos for gene transferring.