The Physical Localization Of Five Linkage Groups Of Molecular Linkage Map In Cassava(Manihot Esculenta Crantz)

Cassava(Manihot esculenta Crantz)is an important energy plant and also a kind of important food crops.Many researchers have constructed some cassava genetic maps successively by using multiple markers,but the corresponding relationship between the genetic map and chromosome is unclear.Except our group members integrated the chromosomes with some linkage groups from two genetic maps of cassava which were published by Chen in 2010 and Sraphet in 2011,the corresponding relationships between the karyotype and the others linkage groups were still unclear.In this study,we used fluorescence in situ PCR technology to locate the 10 markers selected from 5 linkage groups physically,then integrated the karyotype and linkage groups where different markers locate,which laid a foundation for cassava molecular and cellular genetic map construction.The results are as follows:1.The markers from the two ends of LG9 which from genetic map of cassava that published by Rabbi in 2012 were selected to synthesize two pairs of primers NS701-L9 and NS272-L9.A 1000bp segment could be amplified by NS701-L9,and two segments which the sizes were almost 160-200bp could be amplified by NS272-L9 in M.SC6.According to the LG7,LG9,LG14,LG20 from the genetic map of cassava published by Sraphet in 2011,we selected the markers from the two ends,then synthesized four pairs of primers,including the NS158-L9,NS198-L9,NS978-L7,SSRY160-L7,SSRY194-L20,SSRY2-L20,SSRY44-L14 and SSRY248-L14.Two segments which the sizes were almost 160-200bp could be amplified by NS158-L9,and an almost 200bp segment could be amplified by NS198-L9.Both NS978-L7 and SSRY160-L7 can amplify one fragment,the size were 240bp and 140bp,respectively.Both SSRY194-L20 and SSRY2-L20 can amplify one fragment,the size were 295bp and 100bp,respectively.An almost 250bp segment could be amplified by SSRY248-L14,and three segments which the sizes were almost 100-180bp could be amplified by SSRY44-L14 in M.SC6.2.The markers NS701 and NS272 from the LG9 of cassava published by Rabbi in 2012 have been sequentially located on the short arm and long arm of chromosomes 9 of M.SC6 by using the technology of in situ PCR and karyotype analysis,the percent distances from centromere to amplification sites were 70.66 and 30.11,respectively.According the karyotype analysis for the metaphase cells,we found the two markers NS701 and NS272 were located on the two arms of same chromosome,this result also further confirmed the LG9 from Rabbi in 2012 was corresponding to the chromosome 9 of M.SC6.3.The markers NS158 and NS198 from the LG9 of cassava published by Sraphet in 2011 have been sequentially located on the short arm and long arm of chromosomes 3 of M.SC6 by using the technology of in situ PCR and karyotype analysis,the percent distances from centromere to amplification sites were 59.07 and 66.58,respectively.According the karyotype analysis for the metaphase cells,we found the two markers NS158 and NS198 were located on the two arms of same chromosome,this result also further confirmed the LG9 from Sraphet in 2011 was corresponding to the chromosome 3 of M.SC6.4.The markers NS978 and SSRY160 from the LG7 of cassava published by Sraphet in 2011 have been sequentially located on the short arm and long arm of chromosomes 2 of M.SC6 by using the technology of in situ PCR and karyotype analysis,the percent distances from centromere to amplification sites were 82.82 and 27.60,respectively.According the karyotype analysis for the metaphase cells,we found the two markers NS978 and SSRY160 were located on the two arms of same chromosome,this result also further confirmed the LG7 from Sraphet in 2011 was corresponding to the chromosome 2 of M.SC6.5.The markers SSRY2 and SSRY194 from the LG20 of cassava published by Sraphet in 2011 have been sequentially located on the short arm and long arm of chromosomes 8 of M.SC6 by using the technology of in situ PCR and karyotype analysis,the percent distances from centromere to amplification sites were 45.12 and 75.82,respectively.According the karyotype analysis for the metaphase cells,we found the two markers SSRY2 and SSRY194 were located on the two arms of same chromosome,this result also further confirmed the LG20 from Sraphet in 2011 was corresponding to the chromosome 8 of M.SC6.6.The markers SSRY44 and SSRY248 from the LG14 of cassava which was published by Sraphet in 2011 were located on the chromosome of SC6 by IS-PCR.The marker SSRY44 was located on the long arm of the chromosome 13 of M.SC6,the percent distance from centromere to amplification site was 71.99.The marker SSRY248 was located on the long arm of the chromosome 8 of M.SC6,the percent distance from centromere to amplification site was 69.83.The two markers SSRY44 and SSRY248 were located on different chromosomes,this result also further confirmed the LG 14 from Sraphet in 2011 may be formed by combining some parts of the two linkage groups.