title: Fruit self-thinning: a trait to consider for genetic improvement of apple tree.
abstract: In apple (Malus×domestica Borkh), as in many fruiting crops, fruit maintenance vs abscission is a major criteria for production profitability. Growers routinely make use of chemical thinning agents to control total fruit load. However, serious threats for the environment lead to the demand for new apple cultivars with self-thinning properties. In this project, we studied the genetic determinism of this trait using a F1 progeny derived from the cross between the hybrid INRA X3263, assumed to possess the self-thinning trait, and the cultivar 'Belrène'. Both counting and percentage variables were considered to capture the fruiting behaviour on different shoot types and over three consecutive years. Besides low to moderate but significant genetic effects, mixed models showed considerable effects of the year and the shoot type, as well as an interaction effect. Year effect resulted mainly from biennial fruiting. Eight Quantitative Trait Locus (QTL) were detected on several linkage groups (LG), either independent or specific of the year of observation or the shoot type. The QTL with highest LOD value was located on the top third of LG10. The screening of three QTL zones for candidate genes revealed a list of transcription factors and genes involved in fruit nutrition, xylem differentiation, plant responses to starvation and organ abscission that open new avenues for further molecular investigations. The detailed phenotyping performed revealed the dependency between the self-thinning trait and the fruiting status of the trees. Despite a moderate genetic control of the self-thinning trait, QTL and candidate genes were identified which will need further analyses involving other progenies and molecular investigations.
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR 1334, AGAP CIRAD-INRA-Montpellier SupAgro Team «Architecture et Fonctionnement des Espèces Fruitières», Montpellier, France; Institut National de la Recherche Agronomique (INRA), UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), AgroCampus-Ouest, Université d'Angers, SFR 4207 QUASAV, Beaucouzé, France.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Celton
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR 1334, AGAP CIRAD-INRA-Montpellier SupAgro Team «Architecture et Fonctionnement des Espèces Fruitières», Montpellier, France.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Kelner
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR 1334, AGAP CIRAD-INRA-Montpellier SupAgro Team «Architecture et Fonctionnement des Espèces Fruitières», Montpellier, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Martinez
authors.affiliation: Pépinières et Roseraies G. Delbard, Commentry, France.
authors.forename: Abdel
authors.initials: A
authors.lastname: Bechti
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR 1334, AGAP CIRAD-INRA-Montpellier SupAgro Team «Architecture et Fonctionnement des Espèces Fruitières», Montpellier, France.
authors.forename: Amina
authors.initials: A
authors.lastname: Khelifi Touhami
authors.affiliation: Pépinières et Roseraies G. Delbard, Commentry, France.
authors.forename: Marie José
authors.initials: MJ
authors.lastname: James
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), AgroCampus-Ouest, Université d'Angers, SFR 4207 QUASAV, Beaucouzé, France.
authors.forename: Charles-Eric
authors.initials: CE
authors.lastname: Durel
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR1345 Institut de Recherche en Horticulture et Semences (IRHS), AgroCampus-Ouest, Université d'Angers, SFR 4207 QUASAV, Beaucouzé, France.
authors.forename: François
authors.initials: F
authors.lastname: Laurens
authors.affiliation: Institut National de la Recherche Agronomique (INRA), UMR 1334, AGAP CIRAD-INRA-Montpellier SupAgro Team «Architecture et Fonctionnement des Espèces Fruitières», Montpellier, France.
authors.forename: Evelyne
authors.initials: E
authors.lastname: Costes
mesh_terms: D020451:Contig Mapping; D003433:Crosses, Genetic; D005638:Fruit / Q000502:physiology*; D017343:Genes, Plant; D008040:Genetic Linkage; D005838:Genotype; D027845:Malus / Q000235:genetics* / Q000502:physiology; D008957:Models, Genetic; D010641:Phenotype; D000069600:Plant Breeding; D040641:Quantitative Trait Loci; D014197:Trees / Q000235:genetics* / Q000502:physiology; D052584:Xylem / Q000502:physiology