QTL Mapping For Source And Sink Associated Traits Under Face Condition And The Cloning And Functional Study Of Leaf Color QTL QCC6

Rice(Oryza sativa L.)is one of the most important food crops in the world.In recent years,with the rapid increase of the global population and the decrease of arable land,the problem of food shortage still afflicts many countries.Therefore,it is still one of the focuses of rice genetics and breeding to explore the genes that affect rice yield and apply them to variety improvement to improve rice yield.The storage organs of plants such as seeds,which received optocontract compounds,became the storage of plants.Source refers to the part that provides organic matter for other organs of plants by photosynthesis,which is mainly related to photosynthetic capacity,leaf size and chlorophyll content.The source-reservoir character is the key to rice yield.In the first part of this paper,80 chromosome fragment substitution lines with 9311 as the background and NPB as the imported fragments were investigated for their source(including blade length,blade width,leaf fresh weight,leaf dry weight,Chl a,Chl b and Car)and sink(including primary branch number,secondary branch number,grains per panicle,panicle weight per plant)traits under the natural conditions(Nature field,NF)and high CO2 concentration(Free-air CO2 enrichment,FACE)in the field,and QTL analysis was conducted.The main findings are as follows:1.The trait values of NPB,9311 and CSSLs were different under natural and FACE conditions;2.Under natural and FACE conditions,the correlation between the 11 traits was different;3.The results showed that a total of 49 QTL were detected in the two environments,which were distributed on chromosome 1,3,5,6,7,9 and 12 in rice.These QTL accounted for 6.22%-38.15%of the genetic variation.4.A total of 19 QTL were detected under natural conditions while 30 QTL were detected under FACE conditions,including 2 and 13 specific loci,respectively.The above results indicate that the genes controlling source-sink related traits have different expression patterns at different CO2 concentrations,and these QTL will be of great significance to the in-depth study of rice in respose to future high CO2 climate change.The second part of the paper analyzes the molecular mechanism of the QTL based on the chlorophyll content QTL located by DH population constructed by CJ06/TN1 in the early stage of the laboratory by means of mapping cloning,physiology,molecular biology and bioinformatics analysis.The main findings are as follows:1.The chlorophyll content QTL-qCC6 on chromosome 6 was isolated by map-based cloning.Sequence comparison showed that qCC6 was significantly different between CJ06 and its isogenic line NIL5,but mainly in the promoter region.Transgenic complementary experiments showed that complementary positive plants could restore NIL5 to the CJ06 phenotype;2.Dark induced senescence and natural senescence tests showed that compared with the allele of qCC6CJ06,the plants with allele of qCC6TN1 showed less chlorophyll degradation ability and higher content of chlorophyll protein;3.The isotopic 15N labeling results showed that compared with CJ06,the 15N transport in NIL5 leaves was blocked;4.The comparison of yield traits showed that the grain thickness,1000-grain weight and seed setting rate of NIL5 were significantly reduced,resulting in higher yield of CJ06 than that of NIL5;5.RT-PCR analysis showed that the expression of qCC6 in CJ06 was significantly higher than that in NIL5 in seedling stage and in different flowering stages of rice(0 DAD,15 DAD and 30 DAD);6.The comparison of whole-genome resequencing of 195 rice cultivars showed that qCC6 gene could be divided into 12 haplotypes,and the qCC6 of CJ06 and NIL5 were H12 and H11 haplotypes,respectively.Through the correlation analysis of qCC6 gene expression and sequence in 89 randomly selected local varieties,a total of 6 significant correlation sites were detected.Three SNPs were located in the promoter region,and the other three significant association sites were 1 located in the 5’UTR region and 2 located in the 3’UTR region.Three significantly associated loci in the promoter region were verified by lucifase assay,and the results showed that the three loci in the promoter region of the allele qCC6CJ06 promoted the expression;7.Through the comparison of haplotypes in different regions,it is found that H12 haplotype where qCC6CJ06 is located is distributed in low-temperature regions such as high altitude and high latitude.Further low temperature treatments at 4℃ and 16℃ were carried out at the seedling stage and grain-filling stage of CJ06 and NIL5,respectively.The results showed that qCC6CJ06 was induced by low temperature in both stages,but the allele of qCC6TN1 had no obvious response to low temperature.The results of the blue-native polyacrylamide gel-electrophoresis experiment also showed that there was no significant difference in the content of chlorophyll binding protein in CJ06 and NIL5 when treated at 4℃ in seeding stage,but the content of chlorophyll binding protein in NIL5 was significantly higher than that in CJ06 when treated at 16℃ in grain-filling stage,which was consistent with the fact that there was no difference in the content of chlorophyll in the seedling stage,while there was a significant difference in the grain-filling stage.Therefore,we believe that qCC6 is involved in the orderly degradation of chlorophyll in rice leaves and the reuse of nutrients.The expression of qCC6 is induced by low temperature and may be affected by artificial selection in low temperature areas.