Abstract
BackgroundPecan (Carya illinoinensis) and Chinese hickory (C. cathayensis) are important commercially cultivated nut trees in the genus Carya (Juglandaceae), with high nutritional value and substantial health benefits.ResultsWe obtained >187.22 and 178.87 gigabases of sequence, and ∼288× and 248× genome coverage, to a pecan cultivar (“Pawnee”) and a domesticated Chinese hickory landrace (ZAFU-1), respectively. The total assembly size is 651.31 megabases (Mb) for pecan and 706.43 Mb for Chinese hickory. Two genome duplication events before the divergence from walnut were found in these species. Gene family analysis highlighted key genes in biotic and abiotic tolerance, oil, polyphenols, essential amino acids, and B vitamins. Further analyses of reduced-coverage genome sequences of 16 Carya and 2 Juglans species provide additional phylogenetic perspective on crop wild relatives.ConclusionsCooperative characterization of these valuable resources provides a window to their evolutionary development and a valuable foundation for future crop improvement.
Highlights
Pecan (Carya illinoinensis) and Chinese hickory (C. cathayensis) are important commercially cultivated nut trees in the genus Carya (Juglandaceae), with high nutritional value and substantial health benefits
To obtain high-quality reference genome sequences, we sequenced the genomes of Pawnee and ZAFU-1 (Additional file 1: Table S2) using the HiSeq X-Ten sequencing platform from Illumina and single-molecule real-time (SMRT) sequencing technology from Pacific Biosciences (PacBio)
The genus Carya exhibits a remarkable disjunctive distribution between East Asia (EA) and eastern North America (ENA), which offers a model for understanding the phylogenetic relationship between EA and ENA species
Summary
Pecan (Carya illinoinensis) and Chinese hickory (C. cathayensis) are important commercially cultivated nut trees in the genus Carya (Juglandaceae), with high nutritional value and substantial health benefits. Recent studies highlight the health benefits of consuming these nuts in conjunction with reduced incidence of multiple diseases such as tumor, edematogeny, hyperglycemia, and hyperlipidemia [10,11,12]. These beneficial properties have promoted wide cultivation of these species. In China, Chinese hickory provides annual production of close to 30,000 tons with a farm gate value >$125 million (USD) per year before the year 2010 [14]. Annual production exceeded 40,000 tons in China according to statistics of the Chinese State administration of Forestry and Grassland (unpublished data) in 2017
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