| This experiment include two parts: first, the wheat in booting stage was radiated byγray, the doses ofγray were 0.5KRad,1.0KRad, and 1.5KRad, and HMW-GS 5+10 genes was transferred into wheat via pollen tube pathway. Second, the wheat immature embryos were radiated by soft X ray, the doses of X ray were 0.5K Rad,1.0 KRad,2.0KRad and 5.0 KRad,then HMW-GS 5+10 genes were transferred into wheat via particle bombardment. The main purpose was studied on the effect of low dose irradiation on gene transferring in different varieties, improving wheat quality, exploring suitable doses of irradiating plants and immature embryos.The main results as follow:The culture effect of embryo in 13 genotypes showed that there was genotype difference in frequency of callus differentiation and culture capacity except the frequency of callus initiation. ND718, LM29 and LF8 would be the proper materials for gene transform because of the high culture capacity. The different culture effect was found in three types of explants (immature embryo, young spike, and mature embryo) used in the study. However, the frequency of callus initiation in immature embryo and mature embryo was almost the same, but higher than young spike. There was difference in frequency of differentiation among three explants, and the immature embryo ranked the first, young spike next, and mature embryo the last, but immature embryo > mature embryo >young spike when comparing on the basis of cultural capacity. Therefore, immature embryo used as explant in gene transfer would be better than young spike and mature embryo.Three mediums (Ms, 2Ms, B5) on six varieties were studied for culture capacity. The mean frequency of Callus initiation was between 93.98%-100% in three mediums. The mean frequency of callus differentiation in six genotypes was 26.7% on Ms Medium, 18.3% on 2Ms medium, 1.7% on B5 medium respectively. MS was proper medium for immature embryo culture.There was not difference between 0.5KRad treatment and control. The higher soft X-ray dose radiated embryo, the lower callus weight was obtained. Embryo callus weight of 4 genotypes was the highest during 14-16 days after inoculation. The observation showed that there were cellular ultrastructure change in callus cells ,such as nucleus membrane rupture , separate cell wall with cytoplasm, vacuole mitochondria ,and the higher soft X-ray dose radiated callus , the more obvious the cellular ultrastructure was changed.The result of HMW-GS 5+10 genes transferred into LF8 via particle bombardment showed that four transgenic plants with HMW-GS 5+10 genes integrated have been obtained and confirmed by PCR and PCR-Southern hybridization.These four transgenic plants were obtained by soft X-ray radiating immature embryo in low dose 0.5KRad and 1.0 KRad.There were 3 plants with HMW-GS 5+10 confirmed SDS-PAGE in LF8 and FL10,and genes integrated into LF8 and LF10 genome were confirmed by PCR and PCR-Southern hybridization. The transfer frequencies were 1.95%o (one plant) in LF10 radiated by 1.0Kradγray and 6.51‰(two plants) in LF8 radiated by 0.5Kradγray respectively. The result showed that all transgenic plants were obtained in low doses radiation and transgenic frequency was higher than control. There were no transgenic plants obtained in control and other soft X-ray radiation treatment except 0.5KRad and 1.0 KRad. So low doses irradiation treatment increased wheat transgenic frequency. The suitable does of promoting wheat transgenic frequency were around 0.5KRad-1.0KRad in plant radiated byγray and about 0.5-1.0KRad in immature embryo radiated by soft X-ray.Difference in other agronomic characters was found besides target traits, this was caused by gene integrating loci randomly and reaction between genes.The result of quality analysis showed that the sedimentation value, stability, extensibility and energy of transgenic lines were improved in certain degree. SDS-PAGE confirmed that the high molecular weight subunit 5+10 gene had been integrated into all transgenic plants, it meant the target genes were expressed in protein level.
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