Transfer And Mapping Of Valuable Genes From Oryza Officinalis

The genus Oryza consists of more than 20 wild species and two cultivated ones. Both cultivated species, O. sativa and 0. glaberrima, are diploid 2n=24 and have the AA genome. The wild species have 2n=24 or 2n=48 chromosomes, and ten genomes (AA, BB, CC, BBCC, CCDD, EE, FF, GG, HHJJ and HHKK) have so far been designated. The wild species are valuable resources of genes for resistance to major diseases and insects and for tolerance of abiotic stresses. The wealth of untapped genetic diversity of the wild species remains largely unexplored despite the fact that several wild species with AA genome are cross compatible with cultivated rice and have been used in rice breeding programs. O. officinalis, one of the three wild species in China, has great potential in resistance to diseases and insects. To introgess the valuable genes from O. officinalis into cultivated rice and clone the resistant genes to planthoppers and bacterial blight therein, researchs were carried out as follows:1. Establishment of a complete set of individual chromosome additions from Oryza officinalis to cultivated rice using RFLP and GISH analysesInterspecific hybrids were made between one variety (H-1493) of Oryza sativa L. ssp. Japonica (2n=24, AA) and one accession of O. officinalis (2n=24, CC). Hybrid progenies were backcrossed consecutively to H-1493. In all crosses, in vitro embryo rescue was employed to produce hybrids, due to the extremely low crossability of O. officinalis with cultivated rice. Our results showed that the Fi and all the BQ hybrids obtained were completely male sterile. GISH analysis showed that F1 hybrid has 24 chromosome; the twelve green chromosomes belonging to the O. officinalis were distinctive, while the color of the other 12 chromosomes from the O. sativa was red in somatic chromosome prepared from F1 hybrid. Similarly, BC1 plants possessed 36 chromosomes with AAC genome constitution. The chromosome numbers of 84 BC2 plants ranged from 2n to 2n+11. The presence or absence of individual O. officinalis chromosomes in the BC2 progeny was identified through Soutern hybridization. By employing 174 RFLP polymorphic markers distributed evenly on 12 rice chromosomes, alien chromosomes in aneuploid plants were identified and arranged into syntenic groups corresponding to those in O. sativa. With the exception of chromosome 1 and 3 of O. officinalis, on which breakage and mis-fusion occurred, the RFLP maps exhibited good syntenic associations relative to those of the cultivated rice, only that the marker order on different chromosomes were not quite the same. Through RFLP and GISH analyses, the 25 monosomic alien addition lines (MAALs) (2n=25, AA+C) were divided into 12 syntenic groups. Of 12 MAALs designated, MAAL 1, 2, 3, 5, 7 and 10 each contained one plant, MAAL 8, 11 and 12 each contained two, MAAL 6 and 9 each contained four, and MAAL 4 contained five. Some chromosomal arrangements of CC genome such as translocation, duplication and deletion, were detected on different alien chromosomes of MAALs with the exception of MAAL 5 and 7. Such a complete set of O. officinalis MAALs provides a novel manipulation platform for exploiting and utilizing O. officinalis genome and carrying out genetic studies. Our results also suggest that a combination of comparative RFLP maps and GISH analyses was an efficient approach to monitor the alien introgression in theprogenies of interspecific hybridization between O. sativa and wild rice species.2. RFLP analysis of euploid plants from the BC2 progenyTwenty-nine euploid plants derived from intergenomic crosses between O. sativa cv. H-1493 and one accession O. officinalis were analyzed, using 174 polymorphic RFLP markers, and 14 plants were identified to be introgression lines (48.3%), each carrying 1-3 chromosomal segments from O. officinalis. Most introgression lines contained similar O. officinalis segments as defined by common RFLP markers. Of five introgressed RFLP markers, marker C596 from the terminal of the short arm of chromosome 5 detected O. officinalis-specific band...