Construction And Application Of Genetic Transformation System For Sichuan Wheat Elite Cultivars

First successful generation of transgenic wheat (Triticum aetuvivum L.) plants was reported by Vasil et al. (1992) through particle bombardment of plasmid vector pBARGUS into cells of type-C, long-term regenerable embryogenic callus derived form c.v. Pavan. It is a symboliz milestone in the history of wheat transformation. Although wheat transformation has lagged behind other important cereals such as rice and maize due to many reasons, in recent reports indicated that wheat genetic transformations is becoming a routine technique adopted worldwide in different laboratories. This technique was successfully being used for introduction of agronomically important genes for quality improvement, resistance against fungal pathogens, insects, drought stress and herbicide. The development of methodologies for the delivery of exogenous genes provided the new alternative approaches, such as Agrobacterium-mediated and pollen-tube pathway method for particle bombardment. The several elite culitvar genotypes were used, which is not depended on 'model' genotypes, such as Bobwhite.In China, transgenic wheat plants were regenerated in different laboratories. However, in Sichuan province, the transformation of wheat was just carried out in few laboratories. In practice wheat breeding engineering, most foreign cultivars couldn't adapted to the unique entironment in Sichuan. So, it's necessary to establish a genetic transformation system for the elite wheat cultivars planted in Sichuan. In present study, the response in tissue culture of 8 elite varieties or breeding lines with good agronomic characteristics were investigated in order to select the best suitable donor genotypes for genetic transformation. Moreover, the main parameters ofAgrobacterium-mediated and particle bombardment were demonstrated with the aim of optimize the procedures for their genetic transformation. Then two fertile transgenic plants ( c.v chuannongl6) with bar gene were regenerated successfully via microprojectile bombardment method and a transformation system for Sichuan elite cultivars was constructed successfully too. The main results were described as folio wings:1. The frequencies of induced-callus and regeneration capabilities of 8 elite wheat genotypes with good agronomical traits in Sichuan were investigated by the F-test and shortest significant ranges tests(SSR). The results showed that the immature embryo derived from novel cultivar Chuannongl6, which presented the highest callus induction frequency and better regeneration capabilities, was suitable donor explant for wheat transformation. The average frequency of induced-callus derived from immature embryo of chuannong16 (92.9%) was significant highest among 8 genotypes. In given media(N6o), it was 99.25%, with the lowest frequency of initiated shoot directly from explants(1.13%) and more embryogenic callus. 77.78% calli derived from Chuannong 16 cultured by dedifferentiation media MSio regenerated the leaf-like green spot. Chuannongl6, with stable and super high yield, is the new breakthrough of Sichuan wheat breeding. So, the elite genotype Chuannongl6 was selected for donor genotype in Sichuan wheat transformation.2. The significant effects of medium on callus induction were observed by .F-test and SSR. Among 6 media, the frequencies of callus induction on MS2 and N6o were higher than that of the others. The average frequencies of callus induction on MS2 and N60 were 94.0% and 93.1%, respectively. The lowest frequency (83.6%) of callus induction was observed on N61. When MS2 and N6o were selected for callus induction media, it was observed that the frequency of initiated shoot directly from explants on N60 (60.2%) was higher than that of MS2. It indicated that MS2 was superior to N60 for callus induction. Thus, we chose MS2 as callus induction medium in the following procedures. Comparison of the differentiation frequency for each genotype on twomedia MS10 and MS10-1(87.5%, 75.0%), it indicated that MS10 was superior to MS10-1 for green shoot differentiation. So, the call...