| Rice is the main food crop.With the rapid increase of global population,people’s demand for rice is raising.It is of great significance to maintain and improve rice yield.Oryza longistaminata has many excellent characteristics,such as perennial,insect resistance,disease resistance,cold tolerance,stigma exposure,thick stem and so on.Its genome is A’A’,which has high homology with the genome AA of Oryza sativa.So Oryza longistaminata is conducive to hybridization with cultivated rice.Stem circumference of rice is related to lodging resistance.Lodging can affect photosynthesis and result in drop in yield and quality decline of rice.Stigma exsertion rate is one of the key characters to be considered in the preparation of rice hybrids.However,Oryza longistaminata has strong photosensitivity and does not heading under long day.Suitable days to heading is closely related to rice yield.Through genetic analysis of days to heading,stem circumference and stigma exsertion rate of Oryza longistaminata.quantitative trait loci(QTL)controlling related traits were found,which could provide genetic resources for rice breeding.In this experiment,F2 population constructed by crossing between male long stamen wild rice(Oryza longistaminata)and female cultivated rice Balilla was used as study population,The genetic linkage map constructed by InDel molecular markers was used to analyze days to heading,stem circumference and stigma exsertion rate by using the software of QTL analysis.The main results were as follows:1.There were significant differences on days to heading between Oryza longistaminata and Balilla under long day,and the phenotype of days to heading in F2 population showed continuous distribution.By analyzing days to heading of F2 population,six QTL controlling days to heading were obtained,which were located on chromosome 2,4,8 and 9,respectively.The qDTH-8-1 locus on chromosome 8 was detected in F2 population under two-year long day,but it was not detected under short day,suggesting that it was related to photosensitivity.And qDTH-8-1 was the main locus and contributed most to the phenotype on days to heading,including DTH8/GHD8 gene which had been cloned.By sequencing DTH8 allele gene of 4 Oryza sativa and 4 Oryza longistaminata,29 SNP(single nucleotide polymorphism),1 InDel(insertion/deletion)and 2 SSR(simple sequence repeats)were found in the CDS of DTH8 between Oryza sativa and Oryza longistaminata.This leads to a large number of differences in amino acid sequences between the two,including one in the CCAAT-box conserved region:the 86th amino acid location is alanine in Oryza longistaminata,and serine in Oryza sativa.It is speculated that this may be the main reason for the functional differences between the two alleles.In addition,we also detected four other loci qDTH-4-1,qDTH-8-1,qDTH-9-1 and qDTH-9-2,which had been localized but not cloned.They had little effect in this population.2.There were significant differences in stem circumference and rachis circumference between Oryza longistaminata and Balilla.The phenotype of stem circumference and rachis circumference in F2 population showed continuous distribution,and there was a significant positive correlation between them.By analyzing the data of F2 population for two years,thirteen QTL controlling stem circumference and rachis circumference of rice were obtained,which were distributed on chromosome 1,2,3,4,5,7 and 8.There were seven loci controlling stem circumference,qSC-8-1 was the main locus.Six loci controlling rachis circumference,and qRC-8-1 was the main locus.The main loci of stem circumference and rachis circumference were located in the same region,and the main loci qDTH-8-1 on days to heading were also located in the same region.In this study,stem circumference loci qSC-2-1,qSC-2-2,qSC-7-1 and rachis circumference loci qRC-3-1,qRC-7-1 not been reported and belong to new loci,3.There were significant differences in stigma exsertion rate between two parents of Oryza longistaminata and Balilla.Percentage of dual exsertion stigma,percentage of single exsertion stigma and percentage of exsertion stigma in F2 population showed continuous distribution,and there were pairwise correlation among the three traits.Eighteen QTL controlling stigma exsertion rate were obtained from two-year stigma exsertion data,which were distributed on chromosome 2,3,4,5,6 and 9.Six loci controlling percentage of dual exsertion stigma,q-PDES-2-1 belongs to the main locus.Six loci controlling percentage of single exsertion stigma,q-PSES-2-1 belongs to the main locus.And six loci controlling percentage of exsertion stigma,q-PES-2-1 belongs to the main locus.The main loci of the three loci were located in the same region,And belong to new loci.q-PDES-2-2,q-PDES-4-1,q-PDES-6-1,q-PSES-2-2,q-PSES-4-1,q-PSES-9-1,q-PES-2-2,q-PES-4-1,q-PES-5-1,q-PES-9-1 have not been reported and belong to new loci. |
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