Studies On The Transformation Of Genomic DNAs Of Distant Resources In Rice

This study aims at learning the principle of creating new germplasm in plant breeding by using the approach of transformation of the genomic DNA of distant resources.Useful germplasm for hybrid rice breeding has been developed from variants derived from transformation of genomic DNAs of distant species: new CMS line Yewei A and its maintainer line Yewei B, developed'from variant of V20B (rice maintainer line) through transformation of genomic DNAs of 0. minuta; variant also selected from another maintainer line, IR58205B, after introducing the genomic DNA of sorghum, and no morphological segregation has been found among different offspring plants derived from the variant from the D2 on; new restorer line RB207 developed from variant of R207 (rice restorer line) through transformation of the genomic DNA of Echinochloa crusgalli; and new restorer line RS527 , RS559 developed from variant of R527, R559 separately through transformation of genomic DNA of Spirulina platensis. Great improvements in traits of yield, grain quality and resistance to diseases can be found in variant lines compared with their receptors.After research of polymorphism of DNA between variants and its receptors with methods of SSR, AFLP, RAPD, and DNA sequence, a few facts have been revealed for the first time:The results of AFLP analysis show much polymorphism of DNA between variants and its receptors, and indicate special DNA segments from Echinochloa crusgalli and 0. minuta may be integrated into the genome of rice, and also indicate some loci in the receptor genome are tend to be mutable.The results of SSR analysis show much polymorphism of repetitive DNA sequence between variants and its receptors, indicating some special simple repeat DNA segments from distant relatives integrated into the genome of rice probably, and prove variants from DNA transformation can be stable in the second generation.RAPD and DNA sequence analysis reveals DNA polymorphism exists between Yewei B and 0. minuta, and find a pair of DNA fragments in Yewei B and 0. minuta (not in the receptor V20B), VOPG-11975 and DOPG-11975, both with 975 base pairs (bp), are homologous, while no significant homologous DNA sequence with v0PG-11975 or DOPG-11975 has been found in all data libraries of rice genome.All results indicate that transformation of genomic DNAs of distant species is an effective method for creating new rice germplasm. The results of SSR, AFLP, RAPD and DNA sequences analysis of variant lines, receptors and donors of exogenous DNA indicate that special DNA fragments of distant relatives can be integrated into the rice genome; and demonstrate it is the interaction of repetitive DNA sequences and genes between receptor and donor together that decides the mutation in traits of receptor in genomic DNA introduction; and hint about 5% polymorphism of DNA between variant lines and its receptors may be a general rule in genomic DNA transformation.