No Conserved Homoeologous Regions Found in the Sugar Beet Genome

Abstract

Whether amserved hooIoeoIogons regions emt in the sugar­ beet (Belli vulgaris L) genome was investigated by RFLP anal­ ys& Clones from a sugarbeet Pst I library were hybridized to genomic DNA at standard and low stringency. The nwnber of loci detected by each cIooe was determined by ewIuatioo of RFLP band patterm in segregating Fl populations. Two sepa­ nne experiments were canied out: 1) A toCaI of505 clones that had given me to simple band paUerns OIl scnming bkMs and been used as RFLP probes at standard stringency in a previ­ oudy reported RFLP mapping project were re-ewluated for their DNA sequence copy nmnber. The 43 clones for which an eDCt oopy number mold not be determined were re-anaIysed atstandard stringency in a different F 1 population. In addition, the DNA sequence copy number for 50 clones that showed more complex band patterns on screening blots was deter­ mined by RFLP anaIysh at standard stringency. 2) The DNA sequence copy nmnber of 136 selected clones, evenly dW­ tributed over the pnMomly reported RFLP map, ~ deter­ mined at low stringency. The two experiments revealed one du­ plicated sequence at standard sbingency and one additional duplicated sequence at low stringency. Fm1be1'lDOl'e, 475 oftile dooes were coofinned at standard stringency and 94 at low stringency as being singIe-copy sequences. The dODes dis-­tributed randomly over the nine linkage groups of sugarbeet. 100 two duplicated sequences identified mapped to different regions and were SIIITUUIIded by singIe-aJpy ~ Thm, no major hooIoeoIogons regions in the sugarbeet genome were revealed.