title: Mapping and expression of genes associated with raspberry fruit ripening and softening.
abstract: QTL mapping identifies a range of underlying and unrelated genes with apparent roles in raspberry fruit ripening and softening that show characteristic developing fruit expression profiles. Fruit softening is an important agronomical trait that involves a complex interaction of plant cell processes. We have used both qualitative and quantitative scoring of fruit firmness, length, mass, and resistance to applied force to identify QTL in a raspberry mapping population. QTLs were located primarily on linkage group (LG) 3 with other significant loci on LG 1 and LG 5 and showed mostly additive effects between the two parents. The expression of key genes that underlie these QTLs with roles in cell-wall solubility, water uptake, polyamine synthesis, transcription, and cell respiration was tested across five stages of fruit development, from immature green to red ripe fruit, using real-time RT-qPCR. Gene expression patterns showed variable expression patterns across fruit development with a highly significant positive and negative correlation between genes, supporting precise regulation of expression of different cell processes throughout raspberry fruit development. Variable timing in expression was also found in some genes at different fruit development stages between soft and firm cultivars. Multiple processes have a role to play in fruit softening and this will require development of multiple marker combinations to genes that characterise raspberry fruit softening.
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK. craig.simpson@hutton.ac.uk.
authors.forename: Craig G
authors.initials: CG
authors.lastname: Simpson
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Danny W
authors.initials: DW
authors.lastname: Cullen
authors.affiliation: Biomathematics and Statistics Scotland, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Hackett
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Kay
authors.initials: K
authors.lastname: Smith
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, AB24 3UU, UK.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Hallett
authors.affiliation: Biomathematics and Statistics Scotland, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Jim
authors.initials: J
authors.lastname: McNicol
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Woodhead
authors.affiliation: Cell and Molecular Sciences, The James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK.
authors.forename: Julie
authors.initials: J
authors.lastname: Graham
mesh_terms: D002874:Chromosome Mapping; D005638:Fruit / Q000502:physiology*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008040:Genetic Linkage; D010641:Phenotype; D040641:Quantitative Trait Loci; D065856:Rubus / Q000235:genetics* / Q000502:physiology