The Construction Of Peanut Mutant Populations And Expression Analysis Of APETALA2Gene In Peanut

Peanut (Arachis hypogaea L.) is one of the main oil crops which arewidely cultivated in the world. The planting area of peanut in China ranks the secondand with an annual output the first in the world. Ninety percent of peanut varietiesplanting in China at present are “Fu Peanut” and “Shi Tou Qi”, or with their pedigree.The lack of excellent germplasm resources and the excessive dependence on a fewbackbone parent resources are one of the main reasons that restrict the breeding ofnew peanut varieties. Therefore, the creating of excellent germplasm resources thatpossess excellent agronomic traits, strong adaptability, high combining ability andbroad genetic basis has become a common issue of the scientific researchers.Mutations induced by physical and chemical factors have the advantages of easyaccessibility, high mutation rates, etc. Constructing mutant library by physical andchemical methods has become an effective way of creating new germplasm resources.Peanut mutant library will provide abundant germplasm resources and lay a solidfoundation for the breeding of high-yield and high-quality peanut varieties. In thisstudy, we constructed a peanut mutant library by using the methods of ionimplantation mutagenesis and EMS mutagenesis. Different microscopic structuralcharacteristics at different grown stages of screened high and low oil mutant seedswere studied. It was reported that APETALA2(AP2) gene played an important rolein the floral meristem, floral organs consistency and its development.What’s more, theAP2gene also had a large effects on seed size, seed weight and the grain yield.Tostudy the regulation function of AP2in peanut, we obtained6sequences of AP2geneby transcriptome sequencing, and analyzed the expression profile of the6sequencesat four grown stages(20DAF,30DAF,40DAF,50DAF) in peanut seeds using RT-PCR.The results will be a helpful reference for the further study of the gene in peanut. Inthis dissertation, the main contents are as follows:(1) The seeds and flower organs of peanut varieties (or lines)416and606wereinduced by different doses of N+ion beam implantation and0.5%-2.0%ethymethanesulfonate (EMS), respectively. We determined, the suitable dose of ion implantationand EMS using the half lethal concentration and the mount of abundant variationproduced in M2generation as the selection criterias, and dose for416were4×1017 ions/cm~2and1.5%, respectively, and616with that of7×1017and2.0%. The physicaland chemical mutagenesis mutant library of peanuts we built contained various typesof mutants, such as plant height, growth period, sterility, excessive branches, pod, leaf,quality, etc. The mutation frequency of the phenotype was about7.63%. Theseabundant variations will provide rich research materials for peanut geneticimprovement.(2) Take the high-oil mutant6Y3-18and low-oil mutant6Y3-6for example, theuse of paraffin section and semi-thin section, the use of light microscopy and confocallaser scanning the electron microscopy study storage material accumulation process.The results showed that: about30days after flowered, in6Y3-18and6Y3-6, oilbodies and protein bodies were found, then the volume gradually increased, to the lastoil body almost covered the entire cell. Comparatively speaking, in the variety of hua6Y3-18cells Petroleum development period and speed was significantly faster than6Y3-6, the number of large volume of oil bodies were more than6Y3-6, in the6Y3-18cells, numbers of small oil bodies were surrounded in big oil bodies. Studiesshowed that the number and size of the cross-sectional area of the oil bodies andpeanut oil content was positively correlated.(3) Six sequences of peanuts AP2gene were obtained through the transcriptomesequencing. The expression level of the6sequences were analysed at differentdevelopmental stages in peanut seeds by the RT-PCR method. The results indicatedthat there was different at the four developmental stages (20DAF,30DAF,40DAF) inpeanut seeds: the expression level of AP2-2was40DAF>20DAF>30DAF>50DAF.The expression levels of AP2-1and AP2-3were low at each period. The expressionlevel of AP2-4and AP2-5were same: the expression level at20DAF was higher thanthat at30DAF, and it gradually increased from30DAF to50DAF. The highest level ofexpression of AP2-6was found at50DAF, and the expression level graduallyincreased from30DAF to50DAF.