Poplar Comparative Mapping And Important Trait Mapping Of Qtls,

We report a molecular genetic linkage map for an interspecific F1 hybrid population between Populus deltoides (clone 'I―69')×P. euramericana (clone 'I―45') by means of two-way pseudo-testcross mapping strategy. A total 462 markers were available for mapping on the maternal tree 'I-69', including 164 SSRs, 206 AFLPs, 83 RAPDs, 2 SNPs, 6 ISSRs and one sexual differentiation trait. Twenty nine linkage groups were constructed, map length between 9.2 cM~153.9 cM, which 60.4 cM was average group length. The average interval was 4.04 cM between adjacent markers and the largest is 21.8 cM. A total of 1751cM was observed for the 'I-69'map. A total 367 markers were available for mapping on the paternal tree 'I-45', including 153 SSRs, 142 AFLPs, 61 RAPDs, 10 ISSRs and one sexual differentiation trait. Twenty eight linkage groups were constructed, map length between 11.3 cM~142.6 cM, which 58.3 cM was average group length. The average interval was 4.83 cM between adjacent markers and the largest is 22.3 cM. A total of 1634 cM was observed for the 'I-45'map. Using 147 homological markers a integrated map was constructed by JoinMap 2.0 software, including 652 markers (225 SSRs, 288 AFLPs, 120 RAPDs, 16 ISSRs, 2 SNPs and one sexual differentiation trait). Twenty linkage groups were constructed, map length between 25.9 cM to 222 cM. A total 2078 cM map length was observed, which average internal is 3.15 cM and the largest internal is 24.8 cM. One hundred and ten homological SSR markers were used to comparative mapping between our map and P. trichocarpa×P. deltoides map. Nineteen homological linkage groups were aligned. And the orthologous markers showed the synteny between the two maps. Twelve QTLs controlling root growth under water or circularly nutrition culture conditions were mapped. Our result also indicated the dynamics of rooting QTLs effect. Three QTLs involved in Marssoniana brunnea resistance were mapped. And 19 candidate resistance genes were identified based on Populus genome sequence. We also first reported SNPs identification in tree species and revealed assembled ESTs from multiple libraries in public database may provide a rich source of comparative sequences to search for SNPs in poplar genome. Two SNPs were mapped in our map.