Analysis Of Meiotic Chromosomes In The Interspecific Hybrid Generation Of Peanut And Its Genetic Effect

Peanut(Arachis hypogaea L.,2n=4x=40,AABB)is one of the most important oil crops in the world.Artificial selection and domestication led to low genetic diversity in peanut breeding material.In order to increase the diversity for peanut genetic improvement,wild Peanut was used in this study for interspecific hybridization.Our clustering result of 20 peanuts using SSR markers showed that the genetic similarity coefficient ranges from 0.64 to 0.90,with an average of 0.77.The highest genetic similarity coefficient was 0.9 between Tifrunner and ST001.The lowest was 0.6 between ST001 and A.pusilla.The genetic relationship between wild and cultivated peanut varieties laid the foundation for interspecific hybridization study.This research developed six interspecific hybridization F1 plants(w1210,w1401,w1403,w1405,w1510,L)by embryo rescue,using five cultivated peanuts(Tifrunner,baisha 1016,Baitu 131,Si Lihong)as female parents,six wild peanuts(A.glabrata,A.chiquitana,A.maccdoi,A.duranensis,A.stenosperma,A.batizocoi;all are diploid,2n=20)as male parents.Cytologic characterization showed that the six hybrid F1 had 30 chromosomes.The use of molecular marker analysis proved that the sum of gametic chromosomal numbers equals to that of the two parents.Our hybrids also showed irregular union during meiosis and low pollen sterility.Combination of baisha 1016 x A.maccdoi hybrid F1 meiotic chromosome behavior during the period of analysis,reveals the cause of the height of hybrid F1 sterility may be irregular in meiosis metaphase I and chromosomes in meiosis anaphase I and meiosis telophase I showed unequal division.In addition,we investigated resistance and biological properties of hybrid F1.w1212,w1401,w1403,w1405,L showed stronger Late leaf spot resistance than cultivated peanut.The subsequent fluorescence in situ hybridization(FISH)utilized probes of telomere repeats,5S rDNA,45 S rDNA,A.duranensis,A.stenosperma and A.ipaensis genomic DNA.Our result indicated that each of the three genomic karyotypes of w1401 is identical with A and B genome of Yuhua15 and A.stenosperma.This study provided cytogenetic method for characterizing progenies of interspecific hybridization F1 plants.Moreover,dominant molecular markers for 29(w1210),34(w1401),55(w1403),118(w1405),41(w1510),98(L)were developed,which could be used to distinguish translocation from introgression in future studies.