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Malus prattii (Rosaceae) is an endemic species to China. Here, the complete chloroplast genome of M. prattii was obtained by using Illumina pair-end sequencing. The M. prattii complete chloroplast genome was 160,239 bp in length, containing a large single-copy region (LSC) of 88,355 bp and a small single-copy region (SSC) of 19,176 bp, which were separated by a pair of inverted repeat regions (IRs) of 26,354 bp. The chloroplast genome of Malus prattii contained 112 unique functional genes, including 78 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. The overall C + G content of the whole genome was 36.5%. A neighbour-joining phylogenetic analysis suggested a close relationship between M. prattii and M. micromalus.

Flower bud formation in ‘Fuji’ apple (Malus domestica Borkh.) is difficult, which severely constrains commercial production. Spermidine (Spd) plays an important role in floral induction, but the mechanism of its action is incompletely understood. To investigate the effect of Spd on flowering, 6-year-old ‘Fuji’ apple trees were treated with 1 × 10−5 mol L−1 Spd to study the responses of polyamines [putrescine (Put), Spd and spermine (Spm)], hormones [gibberellins (GA3) and abscisic acid (ABA)], and polyamine-, hormone- and flowering-related genes. Spd application promoted flowering during floral induction by increasing MdGA2ox2 (gibberellin 2-oxidase) through GA3 reduction and increasing MdNCED1 and MdNCED3 (9-cis-epoxycarotenoid dioxygenase) through ABA enrichment during 60 to 80 days after full bloom. The flowering rate as well as the expressions of flower-related genes, except for MdLEY (LEAFY), also increased, thereby promoting flowering. In addition, spraying with Spd significantly increased the contents of endogenous polyamines except for Spm in terminal buds by increasing the expressions of polyamine-associated genes. We hypothesize that the contribution of Spd to flowering is related to crosstalk among polyamines, hormone signals, and related gene expressions, which suggests that Spd participates in the apple floral induction process.

Malus hupehensis belongs to the Malus genus (Rosaceae) and is an indigenous wild crabapple of China. This species has received more and more attention, due to its important medicinal, and excellent ornamental and economical, values. In this study, the whole chloroplast (cp) genome of Malus hupehensis, using a Hiseq X Ten sequencing platform, is reported. The M. hupehensis cp genome is 160,065 bp in size, containing a large single copy region (LSC) of 88,166 bp and a small single copy region (SSC) of 19,193 bp, separated by a pair of inverted repeats (IRs) of 26,353 bp. It contains 112 genes, including 78 protein-coding genes (PCGs), 30 transfer RNA genes (tRNAs), and four ribosomal RNA genes (rRNAs). The overall nucleotide composition is 36.6% CG. A total of 96 simple sequence repeats (SSRs) were identified, most of them were found to be mononucleotide repeats composed of A/T. In addition, a total of 49 long repeats were identified, including 24 forward repeats, 21 palindromic repeats, and four reverse repeats. Comparisons of the IR boundaries of nine Malus complete chloroplast genomes presented slight variations at IR/SC boundaries regions. A phylogenetic analysis, based on 26 chloroplast genomes using the maximum likelihood (ML) method, indicates that M. hupehensis clustered closer ties with M. baccata, M. micromalus, and M. prunifolia than with M. tschonoskii. The availability of the complete chloroplast genome using genomics methods is reported here and provides reliable genetic information for future exploration on the taxonomy and phylogenetic evolution of the Malus and related species.

Malus prattii (Rosaceae) is an endemic species to China. Here, the complete chloroplast genome of M. prattii was obtained by using Illumina pair-end sequencing. The M. prattii complete chloroplast ...

Malus transitoria, belongs to the genus Malus of the family Rosaceae, which is native to China. In this study, our results showed the complete chloroplast genome of M. transitoria 159,847 b...