Functional Genes in Bud Dormancy and Impacts on Plant Breeding

Abstract

Bud dormancy is an important developmental stage that affects bud break and blooming in fruit trees. Because prolonged chilling exposure is necessary for dormancy release, climatic changes during dormancy season may affect the progress of bud dormancy and bud break. Although understanding the mechanisms of dormancy and genotype-dependent chilling requirement is important for stable fruit production in the future, the internal control mechanisms are largely unclear. For a better understanding of bud dormancy, numerous genetic and molecular analyses have been performed. For a molecular genomic approach, transcriptome analysis identified the MADS-box transcription factor gene called PmDAM6 as a potential master regulator for dormancy release. Overexpression of PmDAM6 in poplar (Populus spp.) could inhibit shoot growth and promote dormancy induction. The elucidation of the molecular network involved in PmDAMs is ongoing by taking advantage of Prunus mume whole-genome sequences. For the genetic approach, quantitative trait locus (QTL) analysis, using two F1 segregating populations derived from the cross between high-chill and low-chill lines of P. mume, was conducted to identify loci affecting bud dormancy. By using the genotyping-by-sequencing technique, significant QTLs controlling chilling requirement and bud break date of leaf buds were identified at the terminal region of linkage group 4 (LG4) and co-localised with each other, suggesting that this locus controls dormancy release and bud break of leaf buds in P. mume. The use of genetic and molecular analyses to facilitate the breeding of P. mume cultivars that can adapt to various climatic conditions is considered an approach to mitigate global climate change.