Pseudo-chromosome-length genome assembly of a double haploid "Bartlett" pear (Pyrus communis L.)
Linsmith, Gareth ; Rombauts, Stephane ; Montanari, Sara ; Deng, Cecilia H. ; Celton, Jean Marc ; Guérif, Philippe ; Liu, Chang ; Lohaus, Rolf ; Zurn, Jason D. ; Cestaro, Alessandro ; Bassil, Nahla V. ; Bakker, Linda V. ; Schijlen, Elio ; Gardiner, Susan E. ; Lespinasse, Yves ; Durel, Charles Eric ; Velasco, Riccardo ; Neale, David B. ; Chagné, David ; Peer, Yves Van de; Troggio, Michela ; Bianco, Luca - \ 2019
GigaScience 8 (2019)12. - ISSN 2047-217X
chromosome-scale assembly - Hi-C - Pac-Bio sequencing - Pyrus communis L
BACKGROUND: We report an improved assembly and scaffolding of the European pear (Pyrus communis L.) genome (referred to as BartlettDHv2.0), obtained using a combination of Pacific Biosciences RSII long-read sequencing, Bionano optical mapping, chromatin interaction capture (Hi-C), and genetic mapping. The sample selected for sequencing is a double haploid derived from the same "Bartlett" reference pear that was previously sequenced. Sequencing of di-haploid plants makes assembly more tractable in highly heterozygous species such as P. communis. FINDINGS: A total of 496.9 Mb corresponding to 97% of the estimated genome size were assembled into 494 scaffolds. Hi-C data and a high-density genetic map allowed us to anchor and orient 87% of the sequence on the 17 pear chromosomes. Approximately 50% (247 Mb) of the genome consists of repetitive sequences. Gene annotation confirmed the presence of 37,445 protein-coding genes, which is 13% fewer than previously predicted. CONCLUSIONS: We showed that the use of a doubled-haploid plant is an effective solution to the problems presented by high levels of heterozygosity and duplication for the generation of high-quality genome assemblies. We present a high-quality chromosome-scale assembly of the European pear Pyrus communis and demostrate its high degree of synteny with the genomes of Malus x Domestica and Pyrus x bretschneideri.
Development and validation of the Axiom®Apple480K SNP genotyping array
Bianco, Luca ; Cestaro, Alessandro ; Linsmith, Gareth ; Muranty, Hélène ; Denancé, Caroline ; Théron, Anthony ; Poncet, Charles ; Micheletti, Diego ; Kerschbamer, Emanuela ; Pierro, Erica A. Di; Larger, Simone ; Pindo, Massimo ; De Weg, Eric Van; Davassi, Alessandro ; Laurens, François ; Velasco, Riccardo ; Durel, Charles Eric ; Troggio, Michela - \ 2016
The Plant Journal 86 (2016)1. - ISSN 0960-7412 - p. 62 - 74.
genome-wide association study - genotyping - linkage mapping - Malus × domestica Borkh. - SNP chip - validation
Cultivated apple (Malus × domestica Borkh.) is one of the most important fruit crops in temperate regions, and has great economic and cultural value. The apple genome is highly heterozygous and has undergone a recent duplication which, combined with a rapid linkage disequilibrium decay, makes it difficult to perform genome-wide association (GWA) studies. Single nucleotide polymorphism arrays offer highly multiplexed assays at a relatively low cost per data point and can be a valid tool for the identification of the markers associated with traits of interest. Here, we describe the development and validation of a 487K SNP Affymetrix Axiom® genotyping array for apple and discuss its potential applications. The array has been built from the high-depth resequencing of 63 different cultivars covering most of the genetic diversity in cultivated apple. The SNPs were chosen by applying a focal points approach to enrich genic regions, but also to reach a uniform coverage of non-genic regions. A total of 1324 apple accessions, including the 92 progenies of two mapping populations, have been genotyped with the Axiom®Apple480K to assess the effectiveness of the array. A large majority of SNPs (359 994 or 74%) fell in the stringent class of poly high resolution polymorphisms. We also devised a filtering procedure to identify a subset of 275K very robust markers that can be safely used for germplasm surveys in apple. The Axiom®Apple480K has now been commercially released both for public and proprietary use and will likely be a reference tool for GWA studies in apple.
Mechanisms of water supply and vegetation demand govern the seasonality and magnitude of evapotranspiration in Amazonia and Cerrado
Christoffersen, B.O. ; Restrepo-Coupe, N. ; Arain, M.A. ; Baker, I.T. ; Cestaro, B.P. ; Ciais, P. ; Fisher, J.B. ; Galbraith, D. ; Guan, X. ; Hurk, B. van den; Kruijt, B. - \ 2014
Agricultural and Forest Meteorology 191 (2014). - ISSN 0168-1923 - p. 33 - 50.
land-surface scheme - environment simulator jules - carbon-cycle feedbacks - stomatal conductance - regional evapotranspiration - atmosphere interactions - model description - biosphere model - boundary-layer - climate model
Evapotranspiration (E) in the Amazon connects forest function and regional climate via its role in precipitation recycling However, the mechanisms regulating water supply to vegetation and its demand for water remain poorly understood, especially during periods of seasonal water deficits In this study, we address two main questions: First, how do mechanisms of water supply (indicated by rooting depth and groundwater) and vegetation water demand (indicated by stomatal conductance and intrinsic water use efficiency) control evapotranspiration (E) along broad gradients of climate and vegetation from equatorial Amazonia to Cerrado, and second, how do these inferred mechanisms of supply and demand compare to those employed by a suite of ecosystem models? We used a network of eddy covariance towers in Brazil coupled with ancillary measurements to address these questions With respect to the magnitude and seasonality of E, models have much improved in equatorial tropical forests by eliminating most dry season water limitation, diverge in performance in transitional forests where seasonal water deficits are greater, and mostly capture the observed seasonal depressions in E at Cerrado However, many models depended universally on either deep roots or groundwater to mitigate dry season water deficits, the relative importance of which we found does not vary as a simple function of climate or vegetation In addition, canopy stomatal conductance (gs) regulates dry season vegetation demand for water at all except the wettest sites even as the seasonal cycle of E follows that of net radiation In contrast, some models simulated no seasonality in gs, even while matching the observed seasonal cycle of E. We suggest that canopy dynamics mediated by leaf phenology may play a significant role in such seasonality, a process poorly represented in models Model bias in gs and E, in turn, was related to biases arising from the simulated light response (gross primary productivity, GPP) or the intrinsic water use efficiency of photosynthesis (iWUE). We identified deficiencies in models which would not otherwise be apparent based on a simple comparison of simulated and observed rates of E. While some deficiencies can be remedied by parameter tuning, in most models they highlight the need for continued process development of belowground hydrology and in particular, the biological processes of root dynamics and leaf phenology, which via their controls on E, mediate vegetation-climate feedbacks in the tropics.
Development and validation of a 20K Single Nucleotide Polymorphism (SNP) whole genome genotyping array for apple (Malus × domestica Borkh)
Bianco, L. ; Cestaro, A. ; Sargent, D.J. ; Guardo, M. Di; Jansen, J. ; Weg, W.E. van de - \ 2014
PLoS ONE 9 (2014)10. - ISSN 1932-6203 - 9 p.
linkage map - construction - cultivars - alignment - accurate - barley
High-density SNP arrays for genome-wide assessment of allelic variation have made high resolution genetic characterization of crop germplasm feasible. A medium density array for apple, the IRSC 8 K SNP array, has been successfully developed and used for screens of bi-parental populations. However, the number of robust and well-distributed markers contained on this array was not sufficient to perform genome-wide association analyses in wider germplasm sets, or Pedigree-Based Analysis at high precision, because of rapid decay of linkage disequilibrium. We describe the development of an Illumina Infinium array targeting 20 K SNPs. The SNPs were predicted from re-sequencing data derived from the genomes of 13 Malus × domestica apple cultivars and one accession belonging to a crab apple species (M. micromalus). A pipeline for SNP selection was devised that avoided the pitfalls associated with the inclusion of paralogous sequence variants, supported the construction of robust multi-allelic SNP haploblocks and selected up to 11 entries within narrow genomic regions of ±5 kb, termed focal points (FPs). Broad genome coverage was attained by placing FPs at 1 cM intervals on a consensus genetic map, complementing them with FPs to enrich the ends of each of the chromosomes, and by bridging physical intervals greater than 400 Kbps. The selection also included ~3.7 K validated SNPs from the IRSC 8 K array. The array has already been used in other studies where ~15.8 K SNP markers were mapped with an average of ~6.8 K SNPs per full-sib family. The newly developed array with its high density of polymorphic validated SNPs is expected to be of great utility for Pedigree-Based Analysis and Genomic Selection. It will also be a valuable tool to help dissect the genetic mechanisms controlling important fruit quality traits, and to aid the identification of marker-trait associations suitable for the application of Marker Assisted Selection in apple breeding programs.
Genome-Wide SNP Detection, Validation, and Development of an 8K SNP Array for Apple
Chagné, D. ; Crowhurst, R.N. ; Troggio, M. ; Davey, M.W. ; Gilmore, B. ; Lawley, C. ; Vanderzande, S. ; Hellens, R.P. ; Kumar, S. ; Cestaro, A. ; Velasco, R. ; Main, D. ; Rees, J.D. ; Iezzoni, A.F. ; Mockler, T. ; Wilhelm, L. ; Weg, W.E. van de; Gardiner, S.E. ; Bassil, N. ; Peace, C. - \ 2012
PLoS ONE 7 (2012)2. - ISSN 1932-6203
x-domestica borkh. - single-nucleotide polymorphisms - transcription factor - malus-domestica - genus vitis - shelf-life - fruit - markers - diversity - discovery
As high-throughput genetic marker screening systems are essential for a range of genetics studies and plant breeding applications, the International RosBREED SNP Consortium (IRSC) has utilized the Illumina Infinium® II system to develop a medium- to high-throughput SNP screening tool for genome-wide evaluation of allelic variation in apple (Malus×domestica) breeding germplasm. For genome-wide SNP discovery, 27 apple cultivars were chosen to represent worldwide breeding germplasm and re-sequenced at low coverage with the Illumina Genome Analyzer II. Following alignment of these sequences to the whole genome sequence of ‘Golden Delicious’, SNPs were identified using SoapSNP. A total of 2,113,120 SNPs were detected, corresponding to one SNP to every 288 bp of the genome. The Illumina GoldenGate® assay was then used to validate a subset of 144 SNPs with a range of characteristics, using a set of 160 apple accessions. This validation assay enabled fine-tuning of the final subset of SNPs for the Illumina Infinium® II system. The set of stringent filtering criteria developed allowed choice of a set of SNPs that not only exhibited an even distribution across the apple genome and a range of minor allele frequencies to ensure utility across germplasm, but also were located in putative exonic regions to maximize genotyping success rate. A total of 7867 apple SNPs was established for the IRSC apple 8K SNP array v1, of which 5554 were polymorphic after evaluation in segregating families and a germplasm collection. This publicly available genomics resource will provide an unprecedented resolution of SNP haplotypes, which will enable marker-locus-trait association discovery, description of the genetic architecture of quantitative traits, investigation of genetic variation (neutral and functional), and genomic selection in apple
Genetic analysis of metabolites in apple fruits indicates an mQTL hotspot for phenolic compounds on linkage group 16
Khan, S.A. ; Chibon, P.Y.F.R.P. ; Vos, R.C.H. de; Schipper, B.A. ; Walraven, A.E.J. ; Beekwilder, M.J. ; Dijk, T. van; Finkers, H.J. ; Visser, R.G.F. ; Weg, W.E. van de; Bovy, A.G. ; Cestaro, A. ; Velasco, R. ; Jacobsen, E. ; Schouten, H.J. - \ 2012
Journal of Experimental Botany 63 (2012)8. - ISSN 0022-0957 - p. 2895 - 2908.
x-domestica borkh. - developing grape berries - quantitative trait loci - malus-pumila mill. - proanthocyanidin biosynthesis - flavonoid biosynthesis - mass-spectrometry - anthocyanidin reductase - microsatellite markers - cisgenic plants
Apple (Malus×domestica Borkh) is among the main sources of phenolic compounds in the human diet. The genetic basis of the quantitative variations of these potentially beneficial phenolic compounds was investigated. A segregating F(1) population was used to map metabolite quantitative trait loci (mQTLs). Untargeted metabolic profiling of peel and flesh tissues of ripe fruits was performed using liquid chromatography-mass spectrometry (LC-MS), resulting in the detection of 418 metabolites in peel and 254 in flesh. In mQTL mapping using MetaNetwork, 669 significant mQTLs were detected: 488 in the peel and 181 in the flesh. Four linkage groups (LGs), LG1, LG8, LG13, and LG16, were found to contain mQTL hotspots, mainly regulating metabolites that belong to the phenylpropanoid pathway. The genetics of annotated metabolites was studied in more detail using MapQTL(®). A number of quercetin conjugates had mQTLs on LG1 or LG13. The most important mQTL hotspot with the largest number of metabolites was detected on LG16: mQTLs for 33 peel-related and 17 flesh-related phenolic compounds. Structural genes involved in the phenylpropanoid biosynthetic pathway were located, using the apple genome sequence. The structural gene leucoanthocyanidin reductase (LAR1) was in the mQTL hotspot on LG16, as were seven transcription factor genes. The authors believe that this is the first time that a QTL analysis was performed on such a high number of metabolites in an outbreeding plant species.