Fine Mapping Of QTL-qRDR-5 For Deep Rooting Ratio In Rice

Rice?Oryza sativa L.?is one of the most important food crops,and rice is the staple food for more than half of the world's population.Water resources are the core elements of rice production and 70%of agricultural water consumption used for rice production,which will severely restrict rice production.The degree of drought is increasing with the global warming,and drought has become one of the main limiting factors for rice production,so it is of great significance to cultivate and promote water-saving and drought-resistance rice?WDR?.The deep root ratio is considered to be an important indicator to measure the drought avoidance,and it is helpful to locate and clone the deep root ratio gene of rice to study the drought resistance mechanism of rice and to save water and drought resistance.Two F₂ populations?BSA10 and BSA9?were constructed by cross-breeding rice varieties in this laboratory,and the QTL for deep root ratio named q RDR-5 was located on chromosome 5?26384379-29957422,3.57Mb?in two populations?BSA10 and BSA9?by QTL-seq.This study will further refine its positioning,the main results are as follows:1. A total of 277 molecular markers with uniform distribution were predicted in the target interval,and 37 pairs of markers with good polymorphism were obtained for fine positioning by polymorphism screening.2. The BSA10 and BSA9 populations were screened twice and once for recombination exchange single plant respectively:in 2018,the BC₃F₂ population?7000strains?of BSA10 was screened using the markers RM274 and Os5g15p295,and 218recombination exchange single plants were obtained;further in 2019,the BC₃F₂population?7000 strains?of BSA10 was screened using the markers RM26 and R5In D31,and 228 recombinant single plants were obtained.In 2019,the BC₄F₂population?8000 strains?of BSA9 was screened using the markers RM274 and R5In D30,and 510 recombinant single plants were obtained.3. Three deep-root ratio tests were carried out for the heterozygous recombination exchange single plant inbred segregation population of the BSA10 population,and the target QTL interval was reduced to 681.16Kb,147.46Kb and 17.37Kb respectively;A deep root ratio test was carried out for the heterozygous recombination exchanged single-plant inbred segregated population of the BSA9 population,and the target QTL interval was reduced to within the range of 65.70Kb,and the target QTL interval of the materials of the two populations overlapped.4. The q RDR-5 region contains 2 candidate genes,LOC?Os05g47810 and LOC?Os05g47820.The two candidate genes are mainly expressed in roots,and there are significant differences in the expression levels in root tips.The prediction results of homeopathic elements in the promoter region indicate that there are hormone response elements and stress response elements in the LOC?Os05g47810 and LOC?Os05g47820promoter regions,indicating that they may be related to plant stress resistance and growth and development processes.