Project description:Oxalidaceae is one of the most important plant families in horticulture, and its key commercially relevant genus, Averrhoa, has diverse growth habits and fruit types. Here, we describe the assembly of a high-quality chromosome-scale genome sequence for Averrhoa carambola (star fruit). Ks distribution analysis showed that A. carambola underwent a whole-genome triplication event, i.e., the gamma event shared by most eudicots. Comparisons between A. carambola and other angiosperms also permitted the generation of Oxalidaceae gene annotations. We identified unique gene families and analyzed gene family expansion and contraction. This analysis revealed significant changes in MADS-box gene family content, which might be related to the cauliflory of A. carambola. In addition, we identified and analyzed a total of 204 nucleotide-binding site, leucine-rich repeat receptor (NLR) genes and 58 WRKY genes in the genome, which may be related to the defense response. Our results provide insights into the origin, evolution and diversification of star fruit.
Project description:In this study, we determined the complete plastome sequence of Averrhoa carambola L. (Oxalidaceae) (NCBI acc. no. KX364202). To the best of our knowledge, this is the first reported complete plastome sequence from the order Oxalidales. The gene order and structure of the A. carambola plastome are collinear with the typical plastome of land plants. The complete plastome size is 155,965 bp in length and consists of a large single copy region of 87,217 bp and a small single copy region of 17,496 bp, which are separated by a pair of 25,626-bp-long inverted repeat regions. The overall A-T content of the plastome sequence is 61.2%. The plastome contains 111 genes, of which 77 are protein-coding genes, 30 are tRNA genes, and 4 are rRNA genes. Sixteen genes contain one intron and two genes have two introns. A total of 91 simple sequence loci were identified from the genome. Phylogenetic analysis revealed that A. carambola is a sister group of Euonymus japonicus with 100% bootstrap support.
Project description:The fruit of Averrhoa carambola L. (Oxalidaceae), commonly known as star fruit or carambola, is popular in tropical and subtropical regions. Carotenoid-derived components, mainly C13- and C15-norisoprenoids, contribute greatly to the flavor of star fruit. Previously reported norisoprenoids were tentatively identified by GC-MS analysis after enzymatic hydrolysis. To gain accurate information about glycosidically bound flavor precursors in star fruit, a phytochemical study was conducted, which led to the isolation of 16 carotenoid derivatives-One new C13-norisoprenoid glucoside, (5R,6S,7E,9R)-5,6,9-trihydroxy-7-megastigmene 9-O-?-d-glucoside (1); one new C15-norisoprenoid, (6S,7E,10S)-?9,15-10-hydroxyabscisic alcohol (11); and 14 known ones, of which 12 were in glucoside form. The structures of the two new compounds were elucidated on the basis of extensive spectroscopic data analysis and chemical reaction. Compound 11 was a rare C15-norisoprenoid with a double bond between C-9 and C-15, and its possible biogenetic pathway was proposed. The known compounds were identified by comparison of their mass and nuclear magnetic resonance (NMR) data with those reported in the literature. The structure identification of one new (1) and seven known (3?7, 9, and 10) C13-norisoprenoid glucosides from the genus Averrhoa for the first time enriches the knowledge of carotenoid-derived flavor precursors in star fruit.