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Migicovsky Z, Yeats TH, Watts S, Song J, Forney CF, Burgher-MacLellan K, Somers DJ, Gong Y, Zhang Z, Vrebalov J, van Velzen R, Giovannoni JG, Rose JKC, Myles S. Apple Ripening Is Controlled by a NAC Transcription Factor. Front Genet 2021; 12:671300. [PMID: 34239539 PMCID: PMC8258254 DOI: 10.3389/fgene.2021.671300] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/10/2021] [Indexed: 12/12/2022] Open
Abstract
Softening is a hallmark of ripening in fleshy fruits, and has both desirable and undesirable implications for texture and postharvest stability. Accordingly, the timing and extent of pre-harvest ripening and associated textural changes following harvest are key targets for improving fruit quality through breeding. Previously, we identified a large effect locus associated with harvest date and firmness in apple (Malus domestica) using genome-wide association studies (GWAS). Here, we present additional evidence that polymorphisms in or around a transcription factor gene, NAC18.1, may cause variation in these traits. First, we confirmed our previous findings with new phenotype and genotype data from ∼800 apple accessions. In this population, we compared a genetic marker within NAC18.1 to markers targeting three other firmness-related genes currently used by breeders (ACS1, ACO1, and PG1), and found that the NAC18.1 marker was the strongest predictor of both firmness at harvest and firmness after 3 months of cold storage. By sequencing NAC18.1 across 18 accessions, we revealed two predominant haplotypes containing the single nucleotide polymorphism (SNP) previously identified using GWAS, as well as dozens of additional SNPs and indels in both the coding and promoter sequences. NAC18.1 encodes a protein that is orthogolous to the NON-RIPENING (NOR) transcription factor, a regulator of ripening in tomato (Solanum lycopersicum). We introduced both NAC18.1 transgene haplotypes into the tomato nor mutant and showed that both haplotypes complement the nor ripening deficiency. Taken together, these results indicate that polymorphisms in NAC18.1 may underlie substantial variation in apple firmness through modulation of a conserved ripening program.
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Affiliation(s)
- Zoë Migicovsky
- Department of Plant, Food and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada
| | - Trevor H Yeats
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States.,Boyce Thompson Institute, Cornell University, Ithaca, NY, United States
| | - Sophie Watts
- Department of Plant, Food and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada
| | - Jun Song
- Agriculture and Agri-Food Canada, Kentville, NS, Canada
| | | | | | - Daryl J Somers
- Vineland Research and Innovation Centre, Vineland Station, ON, Canada
| | - Yihui Gong
- College of Horticulture, South China Agriculture University, Guangzhou, China
| | - Zhaoqi Zhang
- College of Horticulture, South China Agriculture University, Guangzhou, China
| | - Julia Vrebalov
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States.,Boyce Thompson Institute, Cornell University, Ithaca, NY, United States
| | - Robin van Velzen
- Biosystematics Group, Wageningen University, Wageningen, Netherlands
| | - James G Giovannoni
- Boyce Thompson Institute, Cornell University, Ithaca, NY, United States.,United States Department of Agriculture, Robert W. Holley Center, Cornell University, Ithaca, NY, United States
| | - Jocelyn K C Rose
- Plant Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY, United States
| | - Sean Myles
- Department of Plant, Food and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada
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