Genetic Linkage Maps Of Betula Platyphylla Suk And Betula Pendula Roth Based On RAPD And AFLP

Based on the genetic inheritance and segregation of random amplified polymorphism DNA(RAPDs) and amplified fragment length polymorphism(AFLP) markers,the first middensity linkage map for silver birch was constructed by using a pseudotestcross mapping strategy.A segregating population including 80 progenies from the cross between Betula platyphylla Suk and B.pendula Roth was obtained.A set of 1,200 random oligonucleotide primers were screened,and 203 primers were selected to generate RAPD markers within a sample of 80 F₁ progenies.A total of 291 segregating sites were identified.Among them,230 belonged to 1∶1 segregating site,and 22 belonged to 3∶1 segregating site,others were found distorted from the normal 1∶1 ratio.A set of 64 primer combinations were screened,and 34 pair primer combinations were selected to generate AFLP markers within a sample of 80 F₁ progenies.A total of 451 segregating sites were identified.Among them,362 belonged to 1∶1 segregating site,and 41 belonged to 3∶1 segregating site,20 belonged to 1∶3 segregating site,others were found distorted from the Mondel's ratio.The sites segregating 1∶1(testcross configuration) were used to construct parent-specific linkage maps.Two hundred and twenty-six markers(87 RAPD and 179 AFLP markers) were assigned to B.platyphylla.The resulting linkage maps consisted of 24 groups(four or more sites per group),7 triples and 11 pairs,which covered the map distance about 2,864.5 cM(Kosambi units).The average map distance between adjacent markers was 14.3 cM.Two hundred and twenty-six markers(88 RAPD and 178 AFLP markers) were assigned to B.pendula.The resulting linkage maps consisted of 23 groups(four or more sites per group), 1 triples and 2 pairs,which covered the map distance about 2,489.7 cM(Kosambi units).The average map distance between adjacent markers was 13.1 cM.This map may be used for QTL analysis and molecular assistant selection in birch breeding in the further studies.