The Chromosome Identification Of The Trisomic Lines Of Common Buckwheat (Fagopyrum Esculentum Moench)

Common buckwheat is the key cultivated buckwheat in genus Fagopyrum Mill (Polygonaceae). Common buckwheat and its 25 trisomic lines were studied by means of chromosome karyotype, C-banding, and FISH (Fluorescence in Situ Hybridization). The main results in this study were as follows:(1) The karyotype analysis of common buckwheat root tipe showed that common buckwheat is diploid, 2n=2x=16, and has two pairs of satellite chromosomes, located in 4E and 8E chromosomes. Its karyotype type is 1A. All chromosomes have an arm ratio of 1.01-1.70, are m chromosomes and small chromosomes with the absolute length of 1-4μm. Its karyotype formula is 2n=2x=16=12m+4m(SAT).(2) Karytype analysis of trisomic root tips showed that trisomics of common buckwheat have 17 chromosomes, 2n=2x+1=17. Their karyotypic parameters are the same as common buckwheat. Among 12 trisomic lines in this study, the lines T4 and T10 are 1E trisomics, T9 is 2E trisomics, T11, T13, and T14 are 3E trisomics, T2, T8, and T15 are 4E trisomics, T3 and T7 are 5E trisomics, and T12 is 8E trisomics.(3) The chromosome C-banding analysis of root tip metapase cells for common buckwheat showed that every chromosome has 2-4 bandings, different from each other, which can be used in chromosome identification.(4) The two-colour FISH of Digoxigenin-labled 45S rDNA and Biotin- labled 5S rDNA as probes showed that 45S and 5S rDNA in common buckwheat share the same six loci on three pairs of chromosomes. Among them, four loci were on short arm of 4E and 8E satellite chromosomes and two near centric region of long arm of 6E chromosomes. Their centesimal distances were 31.23±1.0%, 28.46±2.0%, and 20±0.50%, respectively.(5) The two-colour FISH for 9 trisomic lines showed that there are seven 45S, 5S rDNA-locus chromosomes were founded in trisomic lines T8 and T15 (4E trsomics), and in trisomic line T12 (8E trsomics). In other trisomic lines (T4, T5, T7, T9, T10, T13), there are only six 45S, 5S rDNA- locus chromosomes, indicating that their trisomic lines are not 4E, 6E or 8E trisomics.