Studies On Hereditary And Molecular Mechanisms Of Tolerance To Low-phosphorus Traits In Dongxiang Wild (Oryza Rufipogon Griff.)

Available phosphorus deficiency severely in soil is a major limiting factor for rice production. And the non-renewable phosphate rock will be exhausted. Therefore, it is one of the most important issues on investigation and utilization of phosphorus-deficiency tolerance genes from wild rice, which would provide some important theory and practice value direction for development rice variety with phosphorus-deficiency tolerance. And it is a very important strategy for relieving the shortage of phosphorus resources.In the present study, the phosphorus-deficiency tolerance introgression line IL171 and its parents(Oryza sativa cv. ?Xieqingzao B? and Dongxiang wild rice) were used to investigate the gene expression profiles at early seedling stage by cDNA-AFLP technique under the phosphorus-deficiency stress condition. Real-time fluorescent quantitative PCR was used to verify the differentially expressed genes. Dongxiang wild rice as the donor parent, ?Xieqingzao B? as the receptor parent which were used to build BC1F10 group as the research object.This group of the original genetic map using SSR markers for further encryption, Combined with a new generation of high-throughput sequencing technology and high performance computing analysis technology, the excavation of the low phosphorus tolerance in rice traits related genome area and its related gene analysis,to explore the molecular mechanism of dongxiang wild rice resistance to low phosphorus stress, the excavation of the resistance to low phosphorus related genes, as well as the related traits of QTL mapping and other research to provide the reference.(1) cDNA-AFLP analysis revealed that numerous cDNA fragments(20-159) were obtained in each material under the phosphorus-deficiency condition compared with the control(normal phosphorus level). Compared with ?Xieqingzao B?, the differentially up-regulated and down-regulated cDNA fragments in IL171 was to 36 and 61, respectively. In the Dongxiang wild rice, 79 and 136 cDNA fragments were differentially up-regulated and down-regulated, respectively. Further analysis showed that IL171 and Dongxiang shared the same expression pattern at 13 up-regulated loci and 15 down-regulated loci. Among the 60 recovered and sequenced TDFs(transcript-derived fragments), 50 of them were obtained and their functions were determined through BLAST search against the RAP-DB database. The functions of them were grouped into eight classes, including energy and metabolism, regulating genes, signal transduction and transcription factors et al. Six above functional genes were subjected to real-time fluorescentquantitative PCR(qRT-PCR) analysis which was all in agreement with those of the cDNA-AFLP analysis, comfirming that cDNA-AFLP was a reliable in detecting differentially expressed gens involved in responding to the phosphorus-deficiency stress. The results in this study suggested that partial alien DNA fragments of ‘dongxiang’ related to phosphorus-deficiency tolerance has been transferred into the introgression lines and they could be acted as excellent bridging germplasm in exploring and utilizing the phosphorus-deficiency tolerant gene in rice. In additon, the introgression linses derived from Dongxiang wild rice can be used a good experimental system for understanding the molecular mechanism to tolerate phosphorus-deficiency stress in wild rice.(2) A total of 57 SSR markers were used to screen the polymorphism between?Xieqingzao B? and Dongxiang wild rice, and 12 polymorphic markers were obtained with the polymorphism rate of 21.1%.By using MAPMAKER/EXP 3.0, all the 12 SSR markers were localized onto the chromosomes. The marker-newly-added linkage map consists of 155 SSR markers and covers a length of 1604.6 cM with the average distance of 10.35 cM between adjacent markers. By doing intersection of transcriptome sequencing number and QTL mapping results, getting difference Dongxiang Wild Rice expressed amplified fragment 4953. Differentially expressed genes in the leaves have 2494, which raised the value of greater than 2 has 167, accounting for 6.69 percent, which reduced the value of greater than 2 has 113, accounting for 4.53 percent. Differentially expressed genes in the roots have 2457, which raised values of greater than 2 has 117, accounting for 4.76 percent, which reduced the value of greater than 2 has 179, accounting for 7.28 percent, of these genes are located on chromosome 1, 3, 5, 8, 9, 11, etc. Roots and leaves differences in gene coexpression and down-regulation values of greater than 2 to 36. There are 22 genes up regulation values greater than 2 go co-expression in the roots and leaves. There are 14 genes go down values greater than 2 go co-expression in the roots and leaves.