Evaluation of the hormonal state of columnar apple trees (Malus x domestica) based on high throughput gene expression studies

• Published in: Plant molecular biology Vol. 81; no. 3; pp. 211 - 220
• Main Authors: Krost, Clemens, Petersen, Romina, Lokan, Stefanie, Brauksiepe, Bastienne, Braun, Peter, Schmidt, Erwin R.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-02-2013; Springer Nature B.V
• Subjects: Alleles; Apples; Biochemistry; Biomedical and Life Sciences; Chromosomes, Plant - genetics; Computational Biology; Fruit trees; Gene Expression; Gene Expression Regulation, Plant - physiology; Genes, Plant - genetics; Genotype & phenotype; High-Throughput Nucleotide Sequencing; Homeostasis; Life Sciences; Malus; Malus - genetics; Malus - growth & development; Malus - physiology; Meristem - genetics; Meristem - growth & development; Meristem - physiology; Models, Molecular; Molecular biology; Oligonucleotide Array Sequence Analysis; Phenotype; Plant biology; Plant Growth Regulators - genetics; Plant Growth Regulators - physiology; Plant Pathology; Plant Sciences; Plant Shoots - genetics; Plant Shoots - growth & development; Plant Shoots - physiology; Planting density; Real-Time Polymerase Chain Reaction; RNA, Plant - chemistry; RNA, Plant - genetics; Selective breeding; Sequence Analysis, RNA; Transcriptome; Trees; Phytohormones; Apple; Next generation sequencing RNA-Seq; Selective sweep; Columnar
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/s11103-012-9992-0

The columnar phenotype of apple trees (
Malus x domestica
) is characterized by a compact growth habit with fruit spurs instead of lateral branches. These properties provide significant economic advantages by enabling high density plantings. The columnar growth results from the presence of a dominant allele of the gene
Columnar
(
Co
) located on chromosome 10 which can appear in a heterozygous (
Co
/
co
) or homozygous (
Co
/
Co
) state. Although two deep sequencing approaches could shed some light on the transcriptome of columnar shoot apical meristems (SAMs), the molecular mechanisms of columnar growth are not yet elaborated. Since the influence of phytohormones is believed to have a pivotal role in the establishment of the phenotype, we performed RNA-Seq experiments to study genes associated with hormone homeostasis and clearly affected by the presence of
Co
. Our results provide a molecular explanation for earlier findings on the hormonal state of columnar apple trees. Additionally, they allow hypotheses on how the columnar phenotype might develop. Furthermore, we show a statistically approved enrichment of differentially regulated genes on chromosome 10 in the course of validating RNA-Seq results using additional gene expression studies.