Functional Analysis Of A9-cis-epoxycarotenoid Dioxygenase Gene(CrNCED1) In Citrus Reshni

Citrus is an important cash crop in the south of China. However, abiotic stress especially drought restricts the production of citrus. ABA plays an important role in the adaptability of plant to different stress. Endogenous ABA level in plants can be improved by genetic engineering, which can be an efficient method to improve plant resistance.9-Cis-Epoxycarotenoid Dioxygenase (NCED) is the key regulatory enzyme in the ABA biological synthesis pathway and plays an important role in the accumulation of ABA in plants. The main purpose of this study is to analyze the function of CrNCEDl gene with transformed tobacco. The main results are obtained as belows:1. Kanamycin resistance screening and PCR were used to ensure that T2generation of transgenic tobacco was homozygous. A total of8homozygous transgenic lines, namely, C5-3, C5-5, C5-6, C7-1, C7-4, C7-7, C9-4, C9-5were obtained. CrNCED1gene expression were detected between six transgenic lines and wild-type, the results showed that the CrNCEDl gene in transgenic plants have different levels of expression, but no expression in wild-type. Select three transgenic lines C5-6, C7-4and C9-4to study the gene function of CrNCEDl gene.2. It is observed that at the seedling stage the root of transformed tobacco are shorter than non-transformed tobacco. To analyze the function of CrNCEDl gene, transformed and non-transformed tobacco seedlings were grow on MS medium containing ABA,. On the medium containing ABA, the root of transformed tobacco grow faster than non-transformed tobacco.3. The results of relative water loss, water content, relative electrolyte leakage and NBT, DAB staining between transformed and non-transformed tobacco under dehydration, drought and salt showed the transformed tobacco had better water status and less damage to the membrane. The NBT and DAB staining revealed that less ROS level was observed in the transformed plants. Under the treatment of H2O2, the content of chlorophyll of transformed tobacco was higher than non-transformed tobacco. The over-expression of CrNCED1in tobacco enhanced the tolerance to stress.