Spring Is Coming: Genetic Analyses of the Bud Break Date Locus Reveal Candidate Genes From the Cold Perception Pathway to Dormancy Release in Apple (Malus × domestica Borkh.).

Yohanna Evelyn Miotto,Frederico Denardi,Ana Beatriz Costa Czermainski,Diogo Denardi Porto,Marcos Mota Do Carmo Costa,Paulo Ricardo Dias De Oliveira,Carla Andrea Delatorre,Vanessa Buffon,Georgios Joannis Pappas,Roberto Coiti Togawa,Carolina Tessele,Orzenil Bonfim Da Silva-Junior,Priscila Grynberg,Vítor Da Silveira Falavigna,Tiago Sartor,Amanda Malvessi Cattani,Luís Fernando Revers,Marcus Vinícius Kvitschal,Sérgio Amorim De Alencar

doi:10.3389/fpls.2019.00033

Abstract

Chilling requirement (CR) for bud dormancy completion determines the time of bud break in apple (Malus × domestica Borkh.). The molecular control of bud dormancy is highly heritable, suggesting a strong genetic control of the trait. An available Infinium II SNP platform for genotyping containing 8,788 single nucleotide polymorphic markers was employed, and linkage maps were constructed in a F1 cross from the low CR M13/91 and the moderate CR cv. Fred Hough. These maps were used to identify quantitative trait loci (QTL) for bud break date as a trait related to dormancy release. A major QTL for bud break was detected at the beginning of linkage group 9 (LG9). This QTL remained stable during seven seasons in two different growing sites. To increase mapping efficiency in detecting contributing genes underlying this QTL, 182 additional SNP markers located at the locus for bud break were used. Combining linkage mapping and structural characterization of the region, the high proportion of the phenotypic variance in the trait explained by the QTL is related to the coincident positioning of Arabidopsis orthologs for ICE1, FLC, and PRE1 protein-coding genes. The proximity of these genes from the most explanatory markers of this QTL for bud break suggests potential genetic additive effects, reinforcing the hypothesis of inter-dependent mechanisms controlling dormancy induction and release in apple trees.

Highlights

The domesticated apple (Malus × domestica Borkh.), as other temperate fruit trees, has developed the ability to enter a dormant state, which is a mechanism that enables plants to survive seasonal changes and protect sensitive meristems from unfavorable climatic conditions (Rohde and Bhalerao, 2007)
In addition to relevant genes previously described in the literature at the top of the major quantitative trait loci (QTL) in linkage group 9 (LG9), like MdoFLC (MD09G1009100) and MdoPRE1 (MD09G1049300) (Porto et al, 2015), we identified a predicted gene model (MD09G1003800, Chr09:335,088-338,411) that shares similarity to Arabidopsis ICE1 (Supplementary Figure S3)
We present a genetic analysis of the bud break date (BBD) locus in a Full-Sib family derived from a controlled pollination F1 cross between contrasting genotypes for chilling requirement (CR)

Summary

Introduction

The domesticated apple (Malus × domestica Borkh.), as other temperate fruit trees, has developed the ability to enter a dormant state, which is a mechanism that enables plants to survive seasonal changes and protect sensitive meristems from unfavorable climatic conditions (Rohde and Bhalerao, 2007). Using a multiparental population and pedigree-based analysis, Allard et al (2016) detected a strong QTL for bud break and flowering time in the same chromosomal position, as well as another five QTLs of small effect coincident with the position of the DAM genes, the florigen FLOWERING LOCUS T (FT), or the flowering repressor FLOWERING LOCUS C (FLC). A genome-wide association (GWAS) study explored an apple core collection and confirmed the position of the major QTL for time of bud break on LG9, besides narrowing the confidence interval to ∼360 kb and emphasizing the importance of two major candidate genes encoding transcription factors containing NAC or MADS-box (putative FLC) domains (Urrestarazu et al, 2017)

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