QTL精细定位和克隆的策略.ppt

Strategies for Fine Mapping cloning QTLs Most of the important morphological ,physiological and agronomical traits are quantitative traits, which are always analyzed by QTL napping . What’s QTL ? Abundance of available molecular markers facilitate the detection of genetic fundamental of quantitative traits STEP 1 : From Phenotype to QTL Primary Mapping Fine mapping STEP 2 : From QTL to Gene QTL--QTG--QTN Strategies for Fine Mapping cloning QTLs Primary result dependent populations NIL,RHL(HIF),QTR Primary result independent populations IL,CSSL,SSSL Primary result dependent populations – NIL (Near Isogonic Line) Primary result dependent populations – RHL (Residual Heterozygous Line) Primary result dependent populations – QIR (QTL Isogenic Recombinants) Key for fine mapping: Acquire enough recombination events to separate the genes that govern the quantitative trait from closely linked markers. Map Based Cloning – forward genetics strategy Candidate confirmation Transformation Overexpression Gene silencing ect. Why fine mapping cloning? A powerful tool for variety improvement Overlapping substitution line avoid problems associated with environmental variation and genetic background effects in early generation analysis. Extreme sampling method The improvement of genomics facilitate this work ? Progeny testing Why progeny testing? Very a few recombiners Relative minor effect –-hard to distinguish QTL effect to σE Also a way for QTL fine mapping Large population Plenty markers SUMMARY QTLs cloning Dwarf8 tb1 Gn1a,Hd1,Hd6, Hd3a,Ehd1, PSR1,qUVR10 SKC1 etc. The improvement of genomics facilitate this work ? Candidate gene strategy A reverse genetics method How to choose a candidate Gene?Homology searches.Deficiency-complementation test.Polymorphisms in coding or regulatory regions.Mutational analysis.Expression an