Deciphering the genetic determinism of bud phenology in apple progenies: a new insight into chilling and heat requirement effects on flowering dates and positional candidate genes

Abstract

Summary• The present study investigates the genetic determinism of bud phenological traits using two segregating F 1 apple (Malus · domestica) progenies.• Phenological trait variability was dissected into genetic and climatic components using mixed linear modeling, and estimated best linear unbiased predictors were used for quantitative trait locus (QTL) detection. For flowering dates, year effects were decomposed into chilling and heat requirements based on a previously developed model.• QTL analysis permitted the identification of two major and population-specific genomic regions on LG08 and LG09. Both 'chilling requirement' and 'heat requirement' periods influenced flowering dates, although their relative impact was dependent on the genetic background. Using the apple genome sequence data, putative candidate genes underlying one major QTL were investigated. Numerous key genes involved in cell cycle control were identified in clusters within the confidence interval of the major QTL on LG09.• Our results contribute towards a better understanding of the interaction between QTLs and climatic conditions, and provide a basis for the identification of genes involved in bud growth resumption.

Heritability of flowering time within apple progeny

“…The results of the present study are generally in good agreement with recent findings on the subject (Jung & Müller 2009;Celton et al 2011;Gottschalk & Nocker 2013) and could be applied in future breeding programmes focused on the development of new apple cultivars characterized by very late time of flowering. …”

Genetics and Genomics of Tree Architecture

“…Because in all species, cultivars or clones may be characterized as precocious or late for bud burst, the genetic control of flowering and vegetative phenology has been widely studied in both fruit and forest trees. Many QTLs zones have been detected for the time of vegetative and floral bud break in apple (Celton et al, 2011;van Dyk, Soeker, Labuschagne, & Rees, 2010), almond (S anchez-Pérez, Dicenta, & Martínez-G omez, 2012), apricot (Campoy, Ruiz, & Egea, 2011), peach (Dirlewanger et al, 2012) and cherry tree (Castede et al, 2014). In forest trees, QTLs have also been reported for bud set and bud flush in Populus (Bradshaw & Stettler, 1995;Frewen et al, 2000), white spruce (Pelgas, Bousquet, Meirmans, Ritland, & Isabel, 2011), Salix (Ghelardini et al, 2014;Tsarouhas, Gullberg, & Lagercrantz, 2003) and bud burst in Quercus (Scotti-Saintagne et al, 2004).…”

Recent Advances in Genetics and Molecular Control of Bud Dormancy in Pipfruits

“…The region of interest was defined as the first 4 million base pairs from chromosome 9 in the apple genome, a region identical to the one found in an independent linkage mapping of dormancy-related traits performed by our own group (Tessele et al manuscript in preparation). Candidate gene analysis of this region revealed enrichment for functional classes such as stimulus, biological regulation, signaling, programmed cell death and cell cycle control (Celton et al 2011). These segregant populations were established in very divergent climatic conditions, yet shared the same genomic region as containing most of the genetic control of the timing of bud break.…”

“…The single QTL found was positioned on LG9 and explained around 40 % of the variation in the timing of both vegetative and floral bud break (van Dyk et al 2010). In a similar approach, Celton et al (2011) constructed maps from crossings between 'Starkrimson' and 'Granny Smith' and between X3263 and 'Belrène,' the last consisting of a population of more than 300 individuals. The QTL analysis of timing of bud break revealed several associations for this trait across the genome, the major one being on LG9, in close agreement with the confidence interval found by van Dyk et al (2010).…”