Study On Ae Gene Molecular Marker In Maize And Marker-assisted Selection

Maize is one of the most important crops in the world.In maize,starch is the most important element as industrial raw material.In starch,amylose has a wide range of uses in industry.Amylose has a low proportion in dry weight of maize weight,which restricts application of amylase in maize.So to develop high amylose maize breeding has a great significance on the development of amylase production and procession.As the ae gene which controls amylose content in maize is a recessive one,the use of molecular marker-assisted selection methods for quick choices to future generations can improve breeding efficiency and speed up the breeding process.According to maize starch branching enzyme(ae) gene sequences published in Genebank,we screen the molecular marker,establish the technique of ae gene molecular marker,and apply the system to the selection of backcross generations in high amylose content maize.The result is as follows:1.According to maize starch branching enzyme(ae) gene sequences published in NCBI,we choose a kind of high amylose content maize and a common maize genome as templates and design specific primers to amplificate most sequences of ae gene. Through compare and analysis with the PCR amplification fragment,we find that there is a high homology between the high amylose content maize and the common ones.Except 3 consecutive 3-4bp insertion or deletion,the major differences is SNP and insertion / deletion of single-base.2.We design primers in the different place.With screening,we select a pair of primer between 9 and 10 exon with 4bp deletion as marker primer.We can amplificate a specific fragment of 496bp in maize which has ae gene.With the marker,we detect 14 kinds of high amylose content maize inbred lines and 24 kinds of common maize ones, a ae496 band can be amplificated in the high amylose maize inbred lines genomes, while the bands can't be amplificated in common maize inbred lines.So the marker can be used as ae gene dominant molecular marker.3.We detect the F₁,F₂ and BC₁F₁ generations in 3 portfolios.The results show that the dominant molecular marker is in line with mendel law.4.With analysis of the marker and the amylose content in F2 generation grain,we find that the amylose content of grain which is above 32.1%can be amplificated ae496 band,While the amylose content of maize grain which is below 25.8%can't be amplificated the ae496 band.We cann see the correlation between the ae dominant molecular marker and amylose content in grain.Through the ae496 marker we can select ae gene to obtain high amylose trait.5.Through the molecular marker assisted selection in BC₁F₁,BC₂F₁ generations,we analyse the selective effect in self-hybrid and backcorssing generations.The results show that we can obtain ae gene in future generations by marker-assisted selection.The efficiency of selecting ae gene in backcross generation and its second-generation is 53.3%and 73.3%higher than random selection.It indicates that the use of molecular markers in future generations to select ae gene can enhance selective efficiency significantly.