Doctor of Philosophy (PhD)
Plant, Environmental Management and Soil Sciences
Sequence related amplification polymorphism (SRAP) marker technique was used to assess genetic relationships and diversity among genotypes of Saccharum and allied genera. In the SRAP technique, the primers were arbitrarily designed with an AT- and GC-rich motif to anneal introns and exons, respectively. The level of polymorphism observed proved that the SRAP system was robust and amplified markers across species and genera and established evolutionary history interconnecting members of the Saccharum complex. The resolving power of the SRAP markers coupled with the fact that some of the amplicons could be amplifying gene-rich regions from diverse loci of the genome, was indicative of its potential usefulness for linkage and quantitative trait loci (QTLs) mapping in sugarcane. S. spontaneuam has been the most important source of wild germplasm for sugarcane cultivar development in Louisiana. Genetic diversity and structure of 51 S. spontaneum genotypes in the local collection (USDA, Houma, LA) was assessed using amplified fragment length polymorphism (AFLP) markers. Fifty-one genotypes grouped largely according to their geographical origins namely Central and East zones. The contribution of alleles from the S. spontaneum collection in the modern cultivars was low and about equal. This study also allowed us to realize that S. spontaneum germplasm representing the west zone was not present in the collection. A framework genetic linkage map of ‘LCP 85-384’ was constructed using 300 selfed progeny based on 773 single-dose (SD) markers generated by 64 AFLP, 12 TRAP and 19 SSR markers. Out of 773 SD markers, 717 markers were assigned onto 108 co-segregation groups (CGs) with a cumulative map length of 5,384 cM. With the estimated genome size of 12,720 cM, the map covered an estimated 42% of the genome. Of the 108 CGs, 31 CGs were assigned into 12 homo(eo)logous groups (HGs) based on the SSRs and information from the parental maps. Repulsion phase linkages studied suggested the preponderance of disomic segregation between CGs within the homo(eo)logus chromosomes. The framework map established in this study will provide an important background for mapping QTLs associated with sugar related traits and thus, information will be useful for crossing and selection of clones in the breeding program.
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Andru, Suman, "Genetic linkage map of LCP 85-384, genetic diversity of a S. spontaneum collection and the contribution of S. spontaneum to Louisiana commerical germplasm" (2009). LSU Doctoral Dissertations. 786.
Kimbeng, Collins A.