Does maternal environmental condition during reproductive development induce genotypic selection in Picea abies ?

In forest trees, environmental conditions during reproduction can greatly influence progeny performance. This phenomenon probably results from adaptive phenotypic plasticity but also may be associated with genotypic selection. In order to determine whether selective effects during the reproduction are environment specific, single pair-crosses of Norway spruce were studied in two contrasted maternal environments (warm and cold conditions). One family expressed large and the other small phenotypic differences between these crossing environments. The inheritance of genetic polymorphism was analysed at the seed stage. Four parental genetic maps covering 66 to 78% of the genome were constructed using 190 to 200 loci. After correcting for multiple testing, there is no evidence of locus under strong and repeatable selection. The maternal environment could thus only induce limited genotypic-selection effects during reproductive steps, and performance of progenies may be mainly affected by a long-lasting epigenetic memory regulated by temperature and photoperiod prevailing during seed productio

Cartographie génétique et application à l'étude de l'organisation génomique de la différenciation chez l'épicéa commun (Picea abies (L.) Karst.)

Texte intégral accessible uniquement aux membres de l'Université de LorraineThis thesis is composed two distinct sections. In the first one, two parental linkage maps were constructed based on AFLP, SSR and ESTP markers, using a full-sib family. Linkage groups homology between parental maps, established from 66 common markers, allowed us to integrate both parental maps. The resulting consensus map included 755 markers (661 AFLPs, 74 SSRs, 18 ESTPs, the 5S rDNA and the early cone formation) distributed on 12 linkage groups reflecting the haploid number of chromosomes of Norway spruce. This consensus map which was the first saturated map published in this species was aligned to other published maps of Picea abies and other coniferous species. This comparative mapping showed good conservation of synteny in the different Picea abies maps, but only partial linkage group homology based on a few ESTP markers with Pinus species. In the second section of the thesis, the genomic organisation of geographic differentiation within the natural area of the species was investigated based on AFLP, SSR and ESTP markers previously positioned on the consensus map. Results showed that a small number of markers with significant GST (Nei's genetic differentiation coefficient) values were involved. These differentiated loci were scattered over all linkage groups. Some of them seemed to be linked. Discussion was focused on the glacial and postglacial history of Picea abies in Europe and the evolutionary forces that may affect the genome organisation.Cette thèse comporte deux parties. Dans la première, deux cartes parentales ont été construites à partir d'une famille F1 en utilisant des marqueurs AFLP, SSR et ESTP. La présence de 66 marqueurs communs aux deux parents a permis d'identifier les groupes de liaison homologues entre ces deux cartes parentales et de construire une carte consensus. Cette carte consensus comprend 755 marqueurs (661 AFLP, 74 SSR, 18 ESTP, le 5S et le caractère morphologique " formation précoce des cônes ") répartis sur douze groupes de liaison correspondant au nombre de chromosomes à l'état haploïde chez l'épicéa commun. Elle constitue la première carte saturée obtenue chez cette espèce. Cette carte saturée a été alignée avec d'autres cartes publiées chez l'épicéa et d'autres espèces de conifères. Cette comparaison a révélé une bonne conservation de la synténie entre les cartes d'épicéa, mais seulement une homologie partielle, basée sur quelques marqueurs ESTP, de certains groupes de liaison avec des cartes de pins. Dans la seconde partie, un certain nombre de marqueurs AFLP, SSR et ESTP cartographiés sur la carte consensus ont été utilisés pour étudier l'organisation génomique de la différenciation géographique au sein de l'aire naturelle de l'espèce. Les résultats indiquent qu'un petit nombre de marqueurs avec des GST significatifs sont impliqués dans la différenciation intraspécifique. Ces loci différenciés sont dispersés dans le génome. Certains d'entre eux semblent liés. L'histoire glaciaire et postglaciaire de Picea abies en Europe et les forces évolutives qui peuvent affecter l'organisation du génome ont servis de base à la discussion

Chloroplast and mitochondrial molecular tests identify European x Japanese larch hybrids

International audienceHybrids between European and Japanese larches combine the properties of both parental species (drought resistance, canker resistance, stem straightness) and exhibit a fast growth rate. They are produced in seed orchards, generally by natural pollination. Seeds are collected and used for afforestation as interspecific hybrids. However, there are no convenient tests to assess the interspecific hybrid proportion. In the present study, we developed diagnostic molecular markers suitable for the individual identification of hybrids, whatever their developmental stage. Our strategy involved testing a combination of maternally inherited markers from the mitochondrial genome (mtDNA) and paternally inherited markers from the chloroplast genome (cpDNA). Hybrids were then identified by the presence of a mitochondrial sequence inherited from one parental species and a chloroplast sequence inherited from the other parental species. To achieve this aim, markers discriminating both parental species were first sought. Amplifications of mitochondrial and chloroplast sequences were performed using specific PCR primers. After testing 33 primer pairs in combination with nine restriction enzymes, we detected one mitochondrial marker, f13 which was amplified in Japanese larch and absent in European larch, and one chloroplast marker, ll-TaqI which showed different restriction patterns depending on the species. A restriction fragment of 601 bp was obtained in Japanese larch while two fragments of 120 bp and 481 bp were observed in European larch. These patterns were found in all 197 individuals tested from the two pure species. These markers were then used for the evaluation of the hybrid proportion in a seed lot produced from seed orchards; this was assessed as between 43% and 53% depending on the parental species. The male and female parental species could be determined for each progeny

Comparative genome mapping among Picea glauca, P. mariana X P. rubens and P. abies, and correspondence with other Pinaceae

International audienceA composite linkage map was constructed from four individual maps for the conifer Picea glauca (Moench) Voss, from anonymous and gene-speciWc markfers (714 AFLPs, 38 SSRs, and 53 ESTPs). A total of 12 linkage groups were delineated with an average marker density of 2.7 cM. Macro-synteny and macrocolinearity comparisons with two other composite linkage maps developed for the species complex P. mariana (Mill.) B.S.P. £ P. rubens Sarg., and for P. abies (L.) Karst. revealed an identical number of linkage groups and a remarkable conservation of the gene content and gene order of linkage groups over the million years since the split between these taxa. Identical gene order among taxa was observed for 10 of the 12 assembled composite linkage groups. The discovery of one breakdown in synteny between P. glauca and the other two taxa indicated the occurrence of an inter-chromosomal rearrangement involving an insertional translocation. Analysis of marker colinearity also revealed a putative segmental duplication. The combined information from these three Picea genomes validated and improved large-scale genome comparisons at the intergeneric level in the family Pinaceae by allowing for the identiWcation of 11 homoeologous linkage groups between Picea and Pinus, and nine such groups between Picea and Pseudotsuga menziesii. Notably, the analysis of synteny among the three genera revealed a putative case of chromosomal Wssion and an inter-chromosomal rearrangement in the genome of P. menziesii. Both of these changes are inter-connected, indicating much instability in this part of the P. menziesii genome. Overall, the macro-structure of the Pinaceae genome was well conserved, which is notable given the Cretaceous origin of its main lineages

Does maternal environmental condition during reproductive development induce genotypic selection in Picea abies ?

International audienceIn forest trees, environmental conditions during reproduction can greatly influence progeny performance. This phenomenon probably results from adaptive phenotypic plasticity but also may be associated with genotypic selection. In order to determine whether selective effects during the reproduction are environment specific, single pair-crosses of Norway spruce were studied in two contrasted maternal environments (warm and cold conditions). One family expressed large and the other small phenotypic differences between these crossing environments. The inheritance of genetic polymorphism was analysed at the seed stage. Four parental genetic maps covering 66 to 78% of the genome were constructed using 190 to 200 loci. After correcting for multiple testing, there is no evidence of locus under strong and repeatable selection. The maternal environment could thus only induce limited genotypic-selection effects during reproductive steps, and performance of progenies may be mainly affected by a long-lasting epigenetic memory regulated by temperature and photoperiod prevailing during seed production

Towards construction of an ultra high density linkage map for Pinus pinaster

Two parental linkage maps have been constructed from the P. pinaster reference population (0024 $\times$ C803) based on AFLP, SSR and EST markers. Although segregating polymorphism was low due to a high degree of homozygosity in the parents, 12 linkage groups with 26 to 46 markers each were obtained for each parent. The availibility of 70 anchor points based on fragments common to both parents and based on codominant SSR and EST markers allowed to determine homologous chromosomes for both maps and to construct one integrated map. Total genome length of the integrated map is around 2000 cM including 1182 markers. Since some of the EST and SSR markers are also mapped in different pine species, association of linkage groups of our reference population with those of other published maps was possible.Vers la construction d'une carte génétique ultra-haute densité chez Pinus pinaster. Deux cartes génétiques ont été construites à partir d'un croisement intra-spécifique de P. Pinaster (0024 Landes $\times$ C803 Corse) avec des marqueurs AFLP, SSR et EST. Malgré un faible polymorphisme dû à la forte homozygotie des parents, 12 groupes de liaison comprenant 26 à 46 marqueurs ont été obtenus pour chacune des cartes. La présence de 70 points d'ancrage déterminés à partir des fragments communs aux deux parents a permis d'identifier les chromosomes homologues des deux cartes et de construire une carte consensus d'une longueur totale d'environ 2000 cM et comprenant 1182 marqueurs. La présence de quelques marqueurs EST et microsatellites déjà cartographiés chez différentes espèces de pins a permis d'aligner un certain nombre de groupes de liaison avec cette carte de pin maritime

Linkage mapping and QTL analysis for growth of young Pseudotsuga menziesii plants

A controlled cross between two Douglas-fir trees, from Washington State, have been analysed for genetic mapping and for QTL detection. Their progeny have been measured for stem height, bud flushing, and polycyclism on the second and third year after sawing. A genetic map was drawn from segregations of AFLP markers recorded in 157 seedlings. These markers were obtained with 25 primer pairs tested in other Pinaceae species. Genetic map of the female parent consisted of 123 markers distributed in 24 linkage groups. QTLs have been detected by interval mapping for traits showing a normal distribution (stem height, stem elongation), and by a Kruskal and Wallis test for trait that did not show a normal distribution (bud flushing, polycyclism). QTLs have been detected for all investigated traits. QTLs for growth and flushing traits did not overlapped on the female genetic map. QTLs for vegetative flushing stage of terminal bud recorded in 2001 and for day of bud elongation recorded in 2002 did not overlapped. Further evaluations of quantitative traits are required to test time stability of QTLs