Fine mapping of the temperature-sensitive semi-dwarf (Tssd) locus regulating the internode length in peach (Prunus persica)

As a key component of tree architecture, plant height is an important agronomic trait in fruit trees. Reducing tree height is beneficial for increasing planting density, allowing higher yields, lowering costs and increasing the orchard’s lifespan. However, the genetic and molecular factors that regulate peach height are unknown. Here, we report a semi-dwarf peach mutant, which exhibits extremely shortened internodes at temperature below 30 °C. Genetic analysis indicated that this trait was controlled by a single dominant gene that we have named as temperature-sensitive semi-dwarf (Tssd). To map the Tssd locus, two DNA pools, each consisting of 50 mutant or wild-type siblings, were subjected to specific length amplified fragment sequencing. SLAF analysis followed by marker validation using Sanger sequencing and high-resolution melting genotyping located the Tssd gene in a region spanning approximately 750 kb between 2.35 and 3.10 Mb in scaffold 3 based on the reference peach genome sequence of ‘Lovell.’ Further SNPs were developed for fine mapping the locus, which spans an interval of 500 Kb and contains 69 predicted protein-coding gene models. The SNP markers flanking this interval can be applied in molecular identification of Tssd individuals. The result will provide information on how temperature regulates internode length in temperate fruit trees.