The QTL Mapping Of Traits Related To Drought Tolerance And Genetic Transformation Of Herbicide Tolerance Gene In Rice (Oryza Sativa L.)

The genetic mechanism of rice drought tolerance is becoming hotspot in the field of rice molecular genetics worldwide. The objectives of the present study were to clarify population appearance and relationship in drought tolerance, partial morphological traits, traits related to yield and physiology using a set of recombinant inbred line from hybridization between upland and lowland rice cultivars. The practicability of two evaluation methods was argued for effectively evaluating drought tolerance of the population. A linkage map containing 115 SSR molecular markers was constructed and some QTL of traits related to drought tolerance were mapped on this map. Furthermore, a detailed comparison was made on these QTL detected in upland and lowland conditions. Genetic analyses and QTL mapping were done for the capability of seedling emergence and underground stems. In addition, herbicide tolerance gene bar was transferred into 4 elite upland rice cultivars by particle bombardment. The research results in drought and herbicide tolerance would contribute to solve drought and weeds faced in process of application of upland rice.The major results were listed as follows:(1) The population appearance of drought tolerance, agronomic and physiological traits was described, which revealed that partial traits were influenced by upland rice distinctly. The comparison between population and parents indicated that the suitability of the population was improved in upland and lowland conditions. The two evaluation methods for drought tolerance, ratio of yield in upland to lowland (RYUL) and grading of drought tolerance by eyes (GDTE), could all be used for identifying drought tolerance of lines in the population, but the former seemed to contribute to increasing yield and the latter improving appearance of drought tolerance of vegetable.(2) Underground stem was an important trait for emergence capability of seedling in upland condition. In 5cm sowing depth, the long and thick underground stems promoted rate of emergence remarkably. There were two different emergence types of seedling, types depending on long underground stems and on thick stem bases, which all contributed to seedling emergence. By composite interval mapping (CIM), one QTL was mapped in length and thickness of underground stem, thickness of stem base, rate of emergence respectively.(3) A genetic linkage map containing 115 SSR markers was constructed, and some QTL related to roots in upland condition and aerial agronomic, physiological traits in two conditions were mapped. Twenty three QTL were found on 8 root traits, which distributed on 2nd, 3rd, 4th 6th, 9th chromosomes and part of them clustered together. Twenty five QTL related to 16 aerial traits in upland condition and 16 QTL related to 9 aerial traits in lowland condition were mapped and analyzed. The all results told that the number and location of QTL were distinct largely between upland and lowland conditions for same traits which indicated there were different QTL influencing same traits in upland and lowland conditions.(4) The gene bar was transferred into 4 elite upland rice cultivars using particle bombardment and lots of plantlets with herbicide tolerance were obtained. PCR and Southern blot displayed bar gene had integrated into genome of the plants. Tissue culture indicated that the media supplemented sorbitol could promote frequency of regeneration. The herbicide screening and plantlet regeneration experiments testified that 20mg/L and 1mg/L PPT were suitable for calli screening and regeneration respectively. Some following investigations found some traitvariations in T0, T1 and T2 generations. The successes in transformation would facilitate further herbicide tolerance breeding in upland rice cultivars.AH of the results revealed drought tolerance of rice was a complicated trait and many factors were involved in. The research of drought tolerance should focus on their genetic appearance and response to drought stress as well as their interaction each other. The con...