| Sorghum, one of five topmost important crops worldwide, is a popular resource for biofuel production. As a C4plant, sorghum is characterized by high photosynthetic efficiency, short growth period, low water demand, and strong resistance to drought, salinity and high temperature, and these advantages make it especially suitable to be planted in low-quality soils and arid regions. The genome of sorghum is small (750Mb for BTX623) and has been sequenced, so it appears to be an ideal model crop. However, it is very difficult to transform exogenous genes into sorghum, which seriously block the development of sorghum genetic engineering. Therefore, it is necessary to establish efficient regeneration and transformation system. This study proposed to discover high performance of transformation methods, with aim to transform exogenous genes into sorghum, and to conveniently screen positive transgenic plants.AtMYB12specifically governs the spatio-temporal synthesis of anthocyanins in Arabidopsis thaliana, so it could be used to produce anthocyanins, serving as the visible marker to distinguish transformed cells from nontransfermed cells. In this work, we built an expression vector pCAMBIA3301::AtMYB12driven by a strong ubiquentin promoter of maize. The construct was transformed into germinating seeds of sorghum through the vacuum-assisted Agrobacterium-mediated transformation method. In order to increase transformation frequency, we designed several combinations in each step of transformation process ranging from the reagents and time of seed sterilization to the antibiotic resistance screening, and comprehensively compared the difference in the influence of these combinations on transformation efficiency. We finally established a considerably efficient transformation method with the transformation rate of4%.Sorghum bmr mutants have low content of lignin. In order to discover the possible molecular contribution of lignin synthesis block, we analyzed the allelic variation of lignin synthesis associated genes CAD7, C4H, PAL-2and PAL-8between twelve bmr mutants and BT×623. CAD7had one nonsense mutant in each of bmr mutants bmr22, bmr27and BN603, but the mutant position was different from each other. C4H exhibited absolutely identical among BT×623and bmr mutants. PAL-2possessed one nonsense mutation and one alternative splicing in bmr23. PAL-8 produced an alternatively spliced transcript in all of bmr mutants. The association between the allelic variations and the reduced lignin content in bmr mutants should to be further confirmed. |
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