Molecular Identification And Drought Resistance Analysis Of Homozygous Transgenic Rice Plants Expressing ABP9 Driven By Stress-inducible Promoter

Abiotic stress, such as drought, high salinity and lowtemperature, adversely affects plant growth and crop production.Rice as an important grain crop requires more water during the wholegrowing season and more sensitive to drought and salt stressconditions. Therefore, breeding drought and salt resistant rice willmake a significant sense to face with acute water shortage andproduce stable or even high yield.A basic region/leucine zipper (bZIP) transcription factor,designated ABP9, has previously been cloned from maize throughyeast one hybrid screening, which specifically binds to the ABRE2(ABA Responsive Element 2) motif of maize caltalase 1 promoter, Theresults in transgenic Arabidopsis have demonstrated that ABP9 playsan important role in plant abiotic stress tolerance via mediating ABAsignaling and ROS-scavening. To further study the function of ABP9 inRice, cultivar Dongjin has been transformed with ABP9 driven by constitutive Ubi and stress-inducible Pabp9 promoters respectively,through agrobacterium-mediated transformation at geneticimprovement of rice for enhanced drought and salty resistance.The objectives of the present study are: (i) to identify the stable andhomozygous transgenic rice lines expressing ABP9 driven by Pabp9promoter through PCR , Southern blot and Northern blot assays overgenerations, (ii) to test the performance of transgenic lines inresponse to drought stress at seedling stage and screen for droughttolerant lines. The results will enable the application of ABP9 functionin rice.The main results obtained are as follows:1. Six homozygous Pabp9-ABP9 transgenic rice lines wererespectivily identified by PCR amplification over generations, whichare catalogued as follows: A212-15-8, A212-15-10, A212-20-1,A212-20-10, A212-20-11, A212-25-11.2. Southern blotting assay showed that A212-20-1、10、11 eachcontain one copy of ABP9 transgene, A212-25-11 two copies,A212-15-8、10 one or two copies.Northern blotting assay showed that ABP9 is expressed inA212-15-10 and A212-20-11.3. In drought tolerance test of ABP9 transgenic rice at seedingstage, the photosynthetic efficiency of the Ubi-ABP9 lines is much higher than wild type under drought conditions, while plants ofPabp9-ABP9 lines are higher than wild type.4. The survival rates of the Ubi-ABP9 transgenic lines afterdrought stress is much higher than that of wild type, while that ofPabp9-ABP9 lines is higher too.