Effect Of Brassiolide On Genetic Transformation Of Immature Embryos In Wheat

Wheat(Triticum aestivum L.) is one of the world’s major food crops. Genetic transformation is a genetics tool for validation of target genes and crop improvement. As compared to other crops, the efficiency of genetic transformation in wheat is still low. The establishment of a stable, high frequency plant regeneration system is the key of wheat genetic transformation. Brassinosteroids(BRs) are classified as the sixth category of plant hormones as these componds have high biological activity at very low dosages. Scientists have found that BRs can promote callus formation and plant regeneration in plant tissue culture. But there are relatively few reports concerning the role of BRs in wheat genetic transformation. In this study, effect of brassinolide(BL) on bombarded callus differentiation and regeneration of six varieties of wheat immature embryos was sudied, by adding different concentrations of BL(0.0, 2.5, 5.0, 25.0 μg·L-1) in differential medium and rooting medium. The main results were as follows:1. BL at 5.0 μg·L-1 in differential medium significantly increased differentiation rates of Zhoumai 18 and Xiaoyan 22 by 20.18% and 13.18% respectively. BL at 25.0 μg·L-1 in differential medium highly significantly decreased differentiation rates of Zhengmai 9023 and Z50 by 61.16% and 42.48% respectively, and significantly decreased differentiation rate of Yangmai 12 by 31.75%.2. BL at 2.5 μg·L-1 in differential medium highly significantly increased regeneration rate of Yangmai 12 by 51.53%. BL at 5.0 μg·L-1 in differential medium significantly increased the regeneration rate of Yangmai 12 by 31.04%. BL at 25.0 μg·L-1 in differential medium highly significantly increased the regeneration rate of Yangmai 158 by 128.84%, but highly significantly decreased regeneration rates of Yangmai 12 and Xiaoyan 22 by 82.21% and 73.50% respectively.3. BL at 2.5 μg·L-1 in rooting medium significantly promoted root elongation growth of the regenerating seedlings of Yangmai 12 and Z50, but had no-significant effect for root of regenerating seedlings of Yangmai 158. When we added BL with 25.0 μg·L-1 in rooting medium, the root growth of the regenerating seedlings of Yangmai 158 was suppressed significantly, and the leaves of the renernerating wheat were long and narrow, and the stems became thin and weak.4. The wheat genotypes showed significant differences in relation to immature embryo callus differentiation and regeneration. The rate of immature embryo callus differentiation was highest in Xiaoyan 22(80.02%) and lowest in Zhengmai 9023(56.92%); the difference between these two was statistically significant. Yangmai 12 and Yangmai 158(9.17%) which showed significant or highly significant rates of regeneration seedling(11.48% and 9.17%, respectively) than the other genotypes..5. The results of PCR analysis showed that three positive plants with EhHOG were detected.