Molecular Mapping of Complex Traits - Genetics, Genomics and Breeding of Crop Plants - page 171

5.3 Conclusion
The genetics of a broad spectrum of traits, including seed oil concentration,
root morphology, branching, seed dormancy, heterosis, male sterility, fertility
restoration, flowering time, seed shattering, self-incompatibility, fatty acid
and tocopherol composition and concentration, agronomical and
physiological traits, drought and diseases resistance have been and are being
analyzed in different mapping populations of sunflower. These traits are
being mapped relative to candidate genes mined from the expressed sequence
tag (EST) databases to provide maps based on transcribed sequences. Recent
advances in experimental and statistical procedures, including the
simultaneous analysis of QTL that segregate in diverse germplasm, should
improved genetic architecture studies of complex traits. However, cost-effective
genomic tools as well as accurate phenotypic analysis are also necessary.
Improved understanding of the evolution and positive impact on the breeding
sunflower should follow advances in the molecular mapping of complex
traits. Apart from MAS, the ultimate objective of QTL mapping might be to
identify the causal genes, or even the causal sequence changes, the quantitative
trait nucleotides (QTN). Most QTN identification has proceeded from whole-
genome scans to initially localize QTL to 10-20 cM intervals, followed by
high resolution mapping, and finally, detailed genetic and complementation
analysis of the sequence variants that co-segregate with the QTL. While this
remains a major challenge, the QTL regions presented in this chapter could
be an initiation point for resolving the gene level.
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