title: Apple russeting as seen through the RNA-seq lens: strong alterations in the exocarp cell wall.
abstract: Russeting, a commercially important defect in the exocarp of apple (Malus × domestica), is mainly characterized by the accumulation of suberin on the inner part of the cell wall of the outer epidermal cell layers. However, knowledge on the underlying genetic components triggering this trait remains sketchy. Bulk transcriptomic profiling was performed on the exocarps of three russeted and three waxy apple varieties. This experimental design was chosen to lower the impact of genotype on the obtained results. Validation by qPCR was carried out on representative genes and additional varieties. Gene ontology enrichment revealed a repression of lignin and cuticle biosynthesis genes in russeted exocarps, concomitantly with an enhanced expression of suberin deposition, stress responsive, primary sensing, NAC and MYB-family transcription factors, and specific triterpene biosynthetic genes. Notably, a strong correlation (R(2) = 0.976) between the expression of a MYB93-like transcription factor and key suberin biosynthetic genes was found. Our results suggest that russeting is induced by a decreased expression of cuticle biosynthetic genes, leading to a stress response which not only affects suberin deposition, but also the entire structure of the cell wall. The large number of candidate genes identified in this study provides a solid foundation for further functional studies.
authors: Plant Cell Wall Integrative Biology, Centre de Recherche Public - Gabriel Lippmann, 41, rue du Brill, Belvaux, L-4422, Luxembourg, legay@lippmann.lu.
authors: Sylvain
authors: S
authors: Legay
authors: Gea
authors: G
authors: Guerriero
authors: Amélie
authors: A
authors: Deleruelle
authors: Marc
authors: M
authors: Lateur
authors: Danièle
authors: D
authors: Evers
authors: Christelle M
authors: CM
authors: André
authors: Jean-Francois
authors: JF
authors: Hausman
mesh_terms: D002473:Cell Wall / Q000235:genetics*; D016000:Cluster Analysis; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D063990:Gene Ontology; D017343:Genes, Plant; D056726:Genetic Association Studies; D008055:Lipids / Q000096:biosynthesis; D027845:Malus / Q000166:cytology* / Q000235:genetics*; D009928:Organ Specificity / Q000235:genetics; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics*; D019441:Plant Epidermis / Q000235:genetics; D017423:Sequence Analysis, RNA / Q000379:methods*; D015398:Signal Transduction / Q000235:genetics; D013312:Stress, Physiological / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism; D014315:Triterpenes / Q000378:metabolism
chemical_list: D008055:Lipids; D014157:Transcription Factors; D014315:Triterpenes; C065875:suberin