The Origin And Evolution Analysis Of The Weedy Rice Using The NrDNA ITS Sequence

Through a long period of natural selection, weedy rice has rich genetic resources, strongadaptability and resistance, such as cold, salinity, submergence tolerance, drought resistance,pest resistance and so on. So it is essential for the development and utilization of weedy ricegenetic resources, riching genetic basis of varieties of cultivated rice for the purpose ofchanging the vicious cycle of rice production situation. The internal transcribed spacer(ITS)of nuclear rDNA is composed of ITS1and ITS2,which are seperated by5.8s rDNA, can bereadily amplified by PCR and sequenced using universal primers．As a noncoding region ofITS1and ITS2has little effect and pressure in circumstance, for their levels of variationprovide a rich site and information system study site information. This allows ITS sequencesare very suitable for a range of molecular operation, has become the most widely used inangiosperm phylogenetic and evolutionary studies of nuclear gene markersThe PCR conditions of the weedy rice nrDNA ITS were optimized in this study, as aresult, the PCR reactions were carried out as follows: each reaction mixture contained1μlgenomic DNA,0.125mM each dNTPs,0.5mM forward and reverse primer,2μl10×PCRreaction buffer, and the final reaction was adjusted to20μl with sterilized ddH2O. Theannealing temperature was57℃. The Response procedures of PCR is: predegeneration for3min at the degree of94,degeneration for45s at the degree of94,annealing for1min at thedegree of57,extending for1min at the degree of72,after cycle of35-38,extending for20minat the degree of72,incubationing at the degree of4.This experiment uses the methods of direct sequencing and the clone sequencing. Thelength of direct sequence of ITS sequence is about650bp. Comparing with the cultivation orwild rice which have already been published in BLASTN of NCBI has homology to99%;and result of clone sequencing is about650bp which is the similar result with the directsequencing, Comparing with this two methods, although they have different, they get theresult of ITS sequence is exact. The gained sequence information will recognize theunderlying reasons and material basis of weedy rice differentiation on the molecular level,thereby can reveal the real proceed mechanism. That provide a theoretical of preservation, exploitation, utilization and rearing rice new varieties in the research of weedy rice effectiveprevention and cure simultaneously. Also expansion of the field of rice breeding and pledgefurther improvement and sustainable production of cultivated rice.