Abstract:

Wheat is a very important crop in China, but its grain production is affected seriously by some fungal diseases such as powdery mildew, rusts, scab and take-all. Especially for the scab, wheat resistance breeding to the pathogen has just made a little progress since the disease was concerned enough by scientists because there is no ideal germplasm in the species. Therefore, it is necessary to transfer some available foreign genes for resistance to scab into wheat by genetic engineering. B-cell leukemia cell line inhibitor, BCL, and ribsome inactive protein, RIP, were reported to be useful in fungal disease control by causing program of cell death or stopping pathogen propagation. Based on such purpose, BCL gene from human and RIP gene from maize were successfully transferred into Yangmai 10 and Bobwhite, Triticum aestivum CV., respectively, by using C58c1 Agrobacterium strain as donor, the wheat immature embryos of four days pre-culture as receptor, and 10－25 mg/L G418 as selection agent. The T0 antibiotics resistant plants were screened by nptⅡ ELISA first (Fig. 3), and transgenic plants were obtained by efficiencies of 1.60% and 1.25% (Table 1), respectively. Then the positive plants were confirmed by Southern blot and Northern blot. Southern result in T₁ generation indicated that the alien genes were integrated into wheat chromosomes by single copy mostly (Fig.3, Fig.4). Northern result in T₁ generation showed that the foreign genes were transcripted into RNA even though gene silence was happened in a very few individuals (Fig.5). The selection gene linked with target gene was also tested in T₁ generation for its genetic analysis by ELISA and PCR. The result showed the segregation ratio of alien genes in T₁ generation was 2.11－2.33∶1, a little bit away from Mendelian inheritance (Table 3). The result also suggested that the aliens could inherit stably from generation to generation. By artificial inoculation of the pathogen, the transgenic plants showed some resistance to scab in artificial climate shelter. Fifteen transgenic lines with less disease percentage of 5.6%－16.1% including BCL-20, BCL-21, RIP-8, and RIP-18 were screened out, and their disease resistance was stronger than sensitive control, Annong 8455, and close to the resistant control, Sumai 3 (Table 2). The resistant lines will be identified further for their potential application in the scab breeding.

Key words: Wheat, BCL gene, RIP gene, Transformation, Scab