| The temporal and spatial expression characteristics of crylAb gene were studied for first time in sorghum by using the transgenic sorghum as test materials. Effects of illumination, temperature, fertilization quantity and irradiation on expression level of crylAb gene were analyzed, and the field performance of crylAb transgenic sorghum was investigated. And the transgenic sorghum was also analyzed at DNA level by RAPD technology. Results can be summarized as follows:CrylAb contents in transgenic sorghum were detected using Envirologix CrylAb/CrylAc QuantiPlate Kits, and the temporal and spatial expression characteristics of crylAb gene in transgenic sorghum were determined. CrylAb content varied significantly with the developmental stages, with a trend as the highest at seedling stage, followed by maturing stage, jointing stage, filling stage and heading stage in order. CrylAb content in different transgenic sorghum lines was also different significantly, and the highest (2.92ng/g) was detected in line SR12-2 and the lowest (1.25ng/g) in line SR20-9 among the five independent transgenic lines used. There was a significant interaction between the developmental stage and the transgenic line at 1% level, by which CrylAb content was affected. There were obvious differences of CrylAb content in different organs, with the highest in the leaf sheath, followed by the leaf, the glume, the seed, the root and the stem in order, while no CrylAb was detected in the anther. There were also obvious differences of CrylAb content in the leaf, the leaf sheath and the stem at different positions. CrylAb content in middle leaves was higher than that in top and base leaves, and higher CrylAb content was found in the middle leaf sheathes followed by the base and top leaf sheathes. However, the highest CrylAb content in the stem was detected in the base.Effects of illumination, temperature, fertilization quantity and irradiation on expression level of Bt gene in transgenic sorghum were illustrated by detectingCrylAb content under different illumination time (10, 12, 14, 16 and 18h), temperature (20, 25, 30, 35 and 40"C), fertilization quantity (0, 300, 450 and 600kg/hm) and irradiation dose (25, 50, 100, 200, 350 and 500Gy). Among the five different illumination times, CrylAb content was the highest in seedling cultured at 12h illumination time (2.10ng/g). CrylAb content in seedlings was the highest at 25 °C (2.24 ng/g) and the lowest at 40"C(0.44 ng/g) among different temperature treatments. Applying nitrogen could increase CrylAb content and the highest was found at fertilization level of 300kg/hm nitrogen used as base among the different nitrogen levels. CrylAb content could also be increased by high irradiation treatments (350Gy and 500Gy) and the highest was found at doses of 500Gy (9.05 ng/g), which was about four times as that without irradiation (2.35ng/g).Insect resistance of transgenic sorghum was investgated in the field, and both of the biological characteristics (leaf length, leaf width, internode length) and major agronomic traits (plant height, spike shape, spike length, the number of first branches, seed colore, glume color and 1000-grain weight) were characterized. The reasons for the changes in partial traits of transgenic sorghum were also analyzed from aspects of inheritance and physiology. In the fields higher insect resistance of the transgenic lines derived from SR21 was observed as a whole compared with others with similar insect resistance. Compared with its parent and somaclonal lines, the transgenic sorhum showed variations in leaf length, internode length, spike length, plant height and so on, but no obvious changes in most traits. The content of photosynthetic pigments in crylAb transgenic sorghum showed temporal and spatial characteristics. Compared with the parnt 115R, transgenic lines showed significant difference in content of photosynthetic pigments at filling later stage, except transgenic line SRI 6-2, being significant at 10% level. And significant differences were also observed in content of chlorophyll a, chlorophyll b and carotenoids between Bt transgenic sorghum and corresponded somaclonal line. These results revealed that the content of photosynthetic pigments in cry lAb transgenic sorghum also changed, being the physiological reason for its variaions in some traits. The variations in DNA levels were analyzed using RAPD technology. Among 100 UBC randon primers used, 80primers showed the amplification, accounting for 80.0%. 32 primers were used to analyse transgenic lines and CK and 4 of them showed polymorphic amplification, accounting for 12.5%, suggesting that variations at DNA level occurred in the transgenic sorghum. This may be the genetical reason for its variaions in some traits of the transgenic sorghum.The results above provided theoretical evidences for clarification of transgens expression rule in plants and for suitable and sustainable application of Bt transgenic sorghum. |
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