gene transposition causing natural variation for growth in arabidopsis thaliana基因换位导致拟南芥的增长自然变异.pdfVIP

Gene Transposition Causing Natural Variation for Growth in Arabidopsis thaliana 1 2 1 1 Daniela Vlad , Fabrice Rappaport , Matthieu Simon , Olivier Loudet * 1 Institut Jean-Pierre Bourgin, UMR1318 INRA-AgroParisTech, Versailles, France, 2 Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, Paris, France Abstract A major challenge in biology is to identify molecular polymorphisms responsible for variation in complex traits of evolutionary and agricultural interest. Using the advantages of Arabidopsis thaliana as a model species, we sought to identify new genes and genetic mechanisms underlying natural variation for shoot growth using quantitative genetic strategies. More quantitative trait loci (QTL) still need be resolved to draw a general picture as to how and where in the pathways adaptation is shaping natural variation and the type of molecular variation involved. Phenotypic variation for shoot growth in the Bur-0 6Col-0 recombinant inbred line set was decomposed into several QTLs. Nearly-isogenic lines generated from the residual heterozygosity segregating among lines revealed an even more complex picture, with major variation controlled by opposite linked loci and masked by the segregation bias due to the defective phenotype of SG3 (Shoot Growth-3), as well as epistasis with SG3i (SG3-interactor). Using principally a fine-mapping strategy, we have identified the underlying gene causing phenotypic variation at SG3: At4g30720 codes for a new chloroplast-located protein essential to ensure a correct electron flow through the photosynthetic chain and, hence, photosynthesis efficiency and normal growth. The SG3/SG3i interaction is the result of a structura