| Rapeseed (Brassica napus L.) is an important oilseed crop in China. China has the largest cultivated area and most production of rapeseed in the world. However, the unit production is far below than that of some countries such as Germany. Undoubtedly, this is a disadvantage factor since the population is increasing while the arable area is decreasing. Thus, this research aimed at obtaining some good materials by incorporating phytohormonal biosynthase gene (SAG12-ipt, SSP-iaaM, SAG12-i/tf-SSP-iaflM) into rapeseed (Brassica napus L.) mediated by Agrobacterium tumefaciens. ipt gene encodes isopentenyl transferase and iaaM gene encodes tryptophan monooxygenase. The main results are as following: 1. Observation and analysis of appearance character of transformed plants(T0)Hypocotyls of rapeseed (D2) were transformed with ipt, iaaM and ipt-iaaM gene. We had obtained 61 kanamycin-resistance lines after screening, rooting, proliferating and transplanting the transformants. The result showed that some obvious discrepancy existed in the transformed plants. As compared with the negative plants, the differences of the SAG12-ipt transgenic plants were major in leaves senescence delay, more branches, longer and curly siliques. The pecialty of wider siliques belonged to the SSP-iaaM transgenic plants. The characteristics of lower height, morebranches, and longer siliques were the discrepancies of SAG12-ipt-SSP-iaaM transgenic plants.Other characters such as fertility were almost uniform with negative plants, which suggested targetgenes had possibly been integrated into rapeseed genome and had been expressed in transformed plants. 2. PCR analysis of plants transformed SAGl2-ipt and SAG12-ipt-SSP-iaaMThe plants transformed SAG12-ipt and SAG12-ipt-SSP-iaaM were validated by PCR using the primer from ipt. The results showed that 9 lines of these transgenic plants had the same bands with the target gene (about 700bp) after agarose gel electrophoresis, which proved that the targetgenes had been integrated into the genome of these lines. 3. Characteristic of transgenic plants (T2) in the fieldThe progeny self-pollination seeds (T0) of transgenic plants and negative control plants were planted in the field at the same time to observe their appearance and genetic stability under the natural conditions.(1). Observing their growth in the field, we found that at the metaphase and anaphase, 3 lines transformed ipt gene shew significant senescence delay and one line had longer siliques; 2 lines transformed iaaM gene shew pre-blooming; 2 lines transformed ipt-iaaM gene shew significant senescence delay and siliques of one line were longer, lower height existed in one line. All of these maintained the variable characters of the T0 generation, which suggested that the target genes had been passed on and expressed steadily in the T1 generation.(2). After measuring their characters in the room, we found that different lines existed significant or most difference in some characters. The characters of transgenic plants containing SAGl2-ipt gene were becoming higher, having more second branches, having longer and more siliques and heavier 1000 seeds weight. Lines containing iaaM gene had more second branches and heavier 1000 seeds weight. Accepting the ipt-iaaM gene, the plants became shorter, and had more second branches, more siliques and heavier 1000 seeds weight, which simultaneously possessed the characters of ipt and iaaM genes. 6 lines were better than others after comparing all characters, and one line (line iaaM-6) of them increased the production to 15.0%.
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