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Abstract Background MicroRNA (miRNA) is a crucial post-transcriptional regulatory factor in plant growth and development. Duplicated genes often exhibit functional divergence due to competition for the identical miRNA binding sites. Kiwifruit (Actinidia spp.) is an economically significant horticultural crop renowned for its distinctive flavor, which is largely attributable to elevated citrate levels during fruit development. However, the mechanisms through which miRNA-targeted modules evolve following duplication events and regulate citrate biosynthesis, thereby influencing the unique flavor profile of kiwifruits, remain poorly understood. Results In this study, we examined the expression patterns of miRNAs and interactions with their targets in kiwifruit fruit samples from various pulp tissues and developmental stages. Our analysis identified 46 miRNAs, comprising 44 known miRNAs and two novel/kiwifruit-specific miRNAs, which targeted a total of 1,474 genes. Correlation analysis revealed weak relationships between the expression levels of miRNAs and their target genes. Among these targets, 27 tandemly duplicated genes, and 782 whole genome duplication (WGD) genes exhibited a loss of miRNA binding sites in one of their duplicated copies. Furthermore, weighted gene co-expression network analysis demonstrated that most duplicated genes clustered into distinct gene modules. These findings suggest that the loss of miRNA targets following duplications contributes to expression divergence among gene duplicates, thereby facilitating stable gene expression within the miRNA-targeted network. For instance, the aconitate hydratase genes AchAco4 and AchAco6 were each targeted by different miRNAs, ach-miR-3774 and ach-miR-10371, respectively. Notably, these genes exhibited distinct expression patterns compared to their duplicated counterparts. Conclusions This study enhances our understanding of how the miRNA-AchAco module regulates citrate content and provides insights into the molecular network that influences the flavor profile of kiwifruit. Clinical trial number Not applicable.

Dryas octopetala L. var. asiatica (Nakai) Nakai 1918 is a dwarf shrub that mainly grow in alpine and arctic zones of the Northern Hemisphere, representing an endemic variety in Asia. In the present study, the complete chloroplast (cp) genome of D. octopetala var. asiatica was first characterized and used for its phylogenetic analysis. The cp genome span 158,271 bp with an overall GC content of 36.5%. A total of 129 genes were identified, including 84 protein-coding genes (PCGs), 37 tRNA genes, and 8 rRNA genes. In addition, repetitive sequences and microsatellites were detected within this species. Phylogenetic analysis involving 39 cp genomes from Rosaceae family indicated that D. octopetala var. asiatica was sister to the clade of Amygdaloideae. This study contributes fundamental insights into the cp genome of Dryas octopetala var. asiatica, which will have expanded its use in photosynthesis and evolutionary study.

Pathogen-induced fruit decay is a significant threat to the kiwifruit industry, leading to considerable economic losses annually. The cell-wall-degrading enzymes (CWDEs) secreted by these pathogens are crucial for penetrating the cell wall and accessing nutrients. Among them, Diaporthe species are recognized as major causal agents of soft rot in kiwifruit, yet their pathogenic mechanisms are not well understood. In this study, we explored the production of various CWDEs secreted by Diaporthe Z1-1N, including polygalacturonase (PG), polymethylgalacturonase (PMG), polygalacturonic acid transeliminase (PGTE), pectin methyltranseliminase (PMTE), endoglucanase (Cx), and β-glucosidase (β-glu), both in liquid cultures and within infected kiwifruit tissues. Our findings revealed significant activities of two pectinases (PG and PMG) and cellulases (Cx and β-glu) in the infected tissues. In contrast, very low levels of PMTE and PGTE activities were observed under the same conditions. When orange pectin served as the carbon source, PG and PMG showed notable activities, while PMTE and PGTE remained inactive. Moreover, the activities of Cx and β-glu significantly decreased by more than 63 times in the liquid medium with carboxymethyl cellulose (CMC) as the carbon source compared to their levels in infected kiwifruit. A further analysis indicated that the necrotic lesions produced by pectinase extracts were larger than those produced by cellulase extracts. Notably, four enzymes—PG, PMG, Cx, and β-glu—exhibited high activities on the third or fourth day post-infection with Diaporthe Z1-1N. These results suggest that Diaporthe Z1-1N secretes a range of CWDEs that contribute to kiwifruit decay by enhancing the activities of PG, PMG, Cx, and β-glu. This study sheds light on the pathogenicity of Diaporthe in kiwifruit and highlights the importance of these enzymes in the decay process.

Postharvest rot caused by various fungal pathogens is a damaging disease affecting kiwifruit production and quality, resulting in significant annual economic losses. This study focused on isolating the strain P3-1W, identified as Diaporthe eres, as the causal agent of ‘Hongyang’ postharvest rot disease in China. The investigation highlighted cell wall degrading enzymes (CWDEs) as crucial pathogenic factors. Specially, the enzymatic activities of cellulase, β-galactosidase, polygalacturonase, and pectin methylesterases peaked significantly on the second day after infection of D. eres P3-1W. To gain a comprehensive understanding of these CWDEs, the genome of this strain was sequenced using PacBio and Illumina sequencing technologies. The analysis revealed that the genome of D. eres P3-1W spans 58,489,835 bp, with an N50 of 5,939,879 bp and a GC content of 50.7%. A total of 15,407 total protein-coding genes (PCGs) were predicted and functionally annotated. Notably, 857 carbohydrate-active enzymes (CAZymes) were identified in D. eres P3-1W, with 521 CWDEs consisting of 374 glycoside hydrolases (GHs), 108 carbohydrate esterase (CEs) and 91 polysaccharide lyases (PLs). Additionally, 221 auxiliary activities (AAs), 91 glycosyltransferases (GTs), and 108 carbohydrate binding modules (CBMs) were detected. These findings offer valuable insights into the CAZymes of D. eres P3-1W.

Alternaria tenuissima can cause leaf spots and fruit decay in some economically important crops. Recently, this species was first reported as a causal agent causing fruit decay in postharvest kiwifruit. Here, a highly contiguous genome assembly 33.87 Mb in size was obtained by a combination of Illumina NovaSeq and PacBio SMRT sequencing methods, yielding five full chromosome-level sequences. This resource provides opportunities for a better understanding of the mechanisms that underpin the pathogenicity of A. tenuissima. [Figure: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Although genome-wide studies have identified a number of candidate regions evolving under selection in domesticated animals and cultivated plants, few attempts have been made, from the point of a definite biological process, to assess sequence variation and characterize the regimes of the selection on miRNA-associated motifs. Here, we performed a genome-wide dissection of nucleotide variation and selection of miRNA targets associated with rice flower development. By sampling and resequencing 26 miRNA targets for globally diverse representative populations of Asian cultivated rice and wild relatives, we found that purifying selection has reduced genetic variation at the conserved miRNA binding sites on the whole, and highly conserved miRNA binding sequences were maintained in the studied rice populations. Conversely, non-neutral evolution of positive and/or artificial selection accelerates the elevated variations at nonconserved binding sites in a population-specific behavior which may have contributed to flower development-related phenotypic variation. Taken together, our results elucidate that miRNA targets involved in flower development are under distinctive selection regimes during rice evolution.

Abstract Genus Filipendula (Rosoideae, Rosaceae) comprises about 15 species and mainly distributed in Northern Hemisphere. The phylogenetic relationships based on the nrITS marker are not consistent with the traditional taxonomic systems of the genus. Here, we first analysed the complete chloroplast (cp) genomes of seven Filipendula species (including two varieties of F. palmate). Our results indicated that the cp genomes of Filipendula species had few changes in size, ranging from 154,205 bp to 154,633 bp and the average of 36.63% GC content. A total of 126 annotated genes had the identical order and orientation, implying that the cp genome structure of Filipendula species was rather conserved. However, the cp genomes of Filipendula species exhibited structural differences, including gene loss, transposition and inversion when compared to those of other genera of Rosoideae. Moreover, SSRs with the different number were observed in the cp genome of each Filipendula species and sequence divergence mainly occurred in noncoding regions, in which four mutational hotspots were identified. In contrast, only two positive selection genes (matK and rps8) were found. Phylogenetic and molecular-dating analysis indicated that Filipendula species were divergent from other genera of Rosoideae at about 82.88 Ma. Additionally, Filipendula species from East Asia were split at about 9.64 Ma into two major clades. These results provide a basis for further studying the infrageneric classification of Filipendula.

Abstract Background Spiraea is a genus of deciduous shrubs that contains 80-120 species, is mainly distributed in the Northern Hemisphere and has diversified in East Asia. Spiraea species are cultivated as ornamental plants and some are used in traditional herbal medicine. Based on morphological characteristics and genetic markers, phylogenetic classification exhibits low discriminatory power. Results In present study, we assembled and characterized the chloroplast (cp) genomes of ten Spiraea species and comparatively analysed with five reported cp genomes of this genus. The cp genomes of the fifteen Spiraea species, ranging from 155,904 to 158,637 bp in length, were very conserved and no structural rearrangements occurred. A total of 85 protein-coding genes (PCGs), 37 tRNAs and 8 rRNAs were annotated. We also examined 1,010 simple sequence repeat (SSR) loci, most of which had A/T base preference. Comparative analysis of cp genome demonstrated that single copy and non-coding regions were more divergent than the inverted repeats (IRs) and coding regions and six mutational hotspots were detected. Selection pressure analysis showed that all PCGs were under purifying selection. Phylogenetic analysis based on the complete cp genome data showed that Spiraea formed a monophyletic group and was further divided into two major clades. Infrageneric classification in each clade was supported with a high resolution value. Moreover, the phylogenetic trees based on each individual mutational hotspot segment and their combined dataset also consisted of two major clades, but most of the phylogenetic relationships of interspecies were not well supported. Conclusions Although the cp genomes of Spiraea species exhibited high conservation in genome structure, gene content and order, a large number of polymorphism sites and several mutation hotspots were identified in whole cp genomes, which might be sufficiently used as molecular markers to distinguish Spiraea species. Phylogenetic analysis based on the complete cp genome indicated that infrageneric classification in two major clades was supported with high resolution values. Therefore, the cp genome data of the genus Spiraea will be effective in resolving the phylogeny in this genus.

Paris stigmatosa is a new described species of Melanthiaceae. In this study, the complete chloroplast (cp) genome sequence of P. stigmatosa was first reported and characterized. The cp genome is 165,623 bp in length and contains a pair of inverted repeats (IRs, 34,165 bp) separated by a large (84,327 bp) and small (12,966 bp) single-copy regions. A total of 113 genes were predicted, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that P. stigmatosa is sister of the clade formed by P. marmorata and P. luquanensis.

The long dormancy period of Paris polyphylla var. yunnanensis seeds affects the supply of this scarce plant, which is used as an important traditional Chinese medicine. Mature seeds with a globular embryo and germinating seeds with developed embryo were used to explore the mechanisms of seed germination in this species. The protein profiles between the mature and germinating seeds were compared using the isobaric tags for relative and absolute quantification (iTRAQ) approach. Of the 4,488 proteins identified, a total of 1,305 differentially expressed proteins (DEPs) were detected. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of these DEPs indicated that metabolic pathways and the biosynthesis of secondary metabolites were the two top pathways. Additionally, phytohormone quantification shows that the abscisic acid (ABA) level significantly decreased, whereas the GA3 level dramatically increased among nine endogenous gibberellins (GAs), resulting in a significant increase of the GA3/ABA ratio in germinating seeds. The biosynthesis pathways of carotenoid as a precursor for ABA production and GA were further analyzed, and showed that proteinic expressions of the candidate genes in the two pathways did not correlate with the transcriptional abundances. However, 9-cis-epoxycarotenoid dioxygenase (NCED), a rate limited enzyme for ABA biosynthesis, was significantly decreased in mRNA levels in germinating seeds. By contrast, gibberellin 20-oxidase (GA20ox), a key enzyme GA biosynthesis, exhibited the major increase in one copy and a slight decrease in three others at the protentional level in germinating seeds. Gibberellin 2-oxidase (GA2ox), an inactivate enzyme in bioactive GAs, has the tendency to down-regulate in mRNA or at the proteinic level in germinating seeds. Altogether, these results suggested that the analyses of ABA and GA levels, the GA3/ABA ratio, and the expressional patterns of their regulatory genes may provide a novel mechanistic understanding of how phytohormones regulate seed germination in P. polyphylla var. yunnanensis.

Paris delavayi Franchet is a perennial herb of the family Melanthiaceae. In this study, the complete chloroplast (cp) genome sequence of P. delavayi was characterized. The cp genome is 164,195 bp in length and contains a pair of inverted repeats (33,415 bp) separated by a large (84,400 bp) and small (12,965 bp) single-copy regions. A total of 112 unique genes were predicted, including 78 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that P. delavayi is sister to P. mairei but with low support.

The first complete chloroplast (cp) genome sequences of an endemic and endangered species in China, Calanthe henryi, were reported in this study. The cp genome of C. henryi was 158,256 bp long, with two inverted repeat (IR) regions of 26,348 bp, a large single copy (LSC) region of 87,137 bp, and a small single copy (SSC) region of 18,423 bp. The cp genome of this species contained 113 genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The overall GC content was 36.7%. Phylogenetic analysis of 60 cp genomes within the subfamily of Epidendroideae suggests that C. henryi is closely related to C. bicolor.

Sorbus L. is a genus of controversy on its taxonomic concept due to great variations in morphological characteristics. Sorbus sensu stricto species, being monophyletic, are characterized as pinnate leaves. However, phylogenetic relationships of these species are somewhat fluid based on morphological characteristics and genetic markers. In this study, the chloroplast (cp) genomes of eight Sorbus s. str. species were characterized and compared with those of twelve released species in this genus. Our results indicated that the plastomes of the twenty Sorbus species had a conserved quadripartite structure, and 129 annotated genes had the same order and showed a good collinearity. Additionally, numerous SSRs were observed in the cp genome of each Sorbus species; most of the sequence variations appeared in non-coding regions, and four intergenic regions were identified as mutation spots. By contrast, protein-coding genes showed low variations under purifying selection. The phylogenetic and molecular-dating analysis showed that Sorbus was resolved into two major clades, in which S. americana forms one clade originating at 51.78 Ma, and the rest of Sorbus formed another clade, splitting at 36.77 Ma into two sister groups with high support values. These results provide a basis for further studying the phylogenetic relationship and biogeography of Sorbus species.

The first complete chloroplast (cp) genome sequences of Pittosporum tobira were reported in this study. The cp genome of P. tobira was 153,754 bp long, which included a large single copy (LSC) region of 85,010 bp and a small single copy (SSC) region of 18,740 bp separated by two inverted repeat (IR) regions of 25,002 bp. The cp genome of this species contained 113 unique genes, including 79 protein-coding genes, 30 transfer RNA genes and 4 ribosomal RNA genes. The overall GC content was 38.3%. Phylogenetic analysis of the complete cp genomes within the order Apiales suggested that P. tobira, the representative of Pittosporaceae, is sister to the families of Apiaceae and Araliaceae.

The complete cp genome of Piuns wangii was 117,014 bp in size, containing a large single copy (LSC, 64,061 bp) region and a small single copy (SSC, 52,007 bp) region separated by two reduced inverted repeats (IRs, 473 bp). A total of 107 genes were predicted, including 73 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Most of the 51 simple sequence repeats (SSRs) were mononucleotides motifs of A/T types and were found to be located in non-coding regions. Phylogenetic analysis of Asian Pinus showed P. wangii clustered a strongly-supported clade with Pinus morrisonicola, Pinus sibirica, Pinus wallichiana, and Pinus pumila.

Achyranthes bidentata (Amarathaceae) has been commonly used as a traditional Chinese medicine in the treatment of osteoporosis and bone nonunion. Here, the complete chloroplast genome of A. bidentata was assembled and characterized. The cp genome is 151,451 bp in length, composed of a pair of 25,150 bp inverted repeat (IR) regions separated by a large single-copy (LSC) region of 83,899 bp and a small single-copy (SSC) region of 17,252 bp. The whole cp genome of A. bidentata contains 130 genes(85 protein-coding genes, 37 tRNAs and eight rRNAs) and the overall GC content is 36.5%. Phylogenetic analysis based on the cp genome data showed that A. bidentata was close to Cyathula capitata.

Acer yangbiense Y.S. Chen & Q.E. Yang is a species of Aceraceae with a very restricted distribution in Yunnan, China. In this study, the complete chloroplast (cp) genome sequence of A. yangbiense was reported and characterized. The cp genome is 155,706 bp in length and contains a pair of inverted repeats (IRs, 25,858 bp) separated by a large (85,859 bp) and small (18,131 bp) single-copy regions. A total of 128 genes were predicted, including 83 protein-coding genes, 37 tRNA genes and 8 rRNA genes. The phylogenetic analysis suggested that A. yangbiense is sister of the clade formed by A. laevigatum, A. palmatum, A. wilsonii, and A. buergerianum.

Engelhardia roxburghiana is a traditional Chinese medicine in the Juglandaceae family. In this study, the complete chloroplast (cp) genome sequence of E. roxburghiana was reported and characterized. The cp genome is 161,550 bp in length and contains a pair of inverted repeats (IRs, 25,862 bp) separated by a large (90,937 bp) and small (18,889 bp) single-copy regions. A total of 113 unique genes were predicted, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that E. roxburghiana is resolved as a sister group to the clade of subfam. Juglandoideae.

Uncaria rhynchophylla is a vine plant belonging to the family Rubiaceae and has been used as medicine for a long time in China. In this study, the complete chloroplast (cp) genome sequence of U. rhynchophylla was first reported and characterized. The cp genome was 154,605 bp in length and contains a pair of inverted repeats (IRs, 34,165 bp each) separated by a large (84,327 bp) and small (12,966 bp) single-copy regions. A total of 113 unique genes were predicted, including 79 protein-coding genes, 30 tRNA genes and 4 rRNA genes. The phylogenetic analysis suggested that U. rhynchophylla was closer to Neolamarckia cadamba.

The first complete chloroplast genome (cp) sequences of Silene jenisseensis were reported in this study. The S. jenisseensis cp genome was 150,299 bp in size, with two inverted repeat (IR) regions of 25,384 bp, the large single-copy (LSC) region of 82,153 bp, and the small single-copy (SSC) region of 17,378 bp. The cp genome of this species contained 111 genes, including 77 protein-coding genes, 4 ribosomal RNA, and 30 transfer RNA genes. The overall GC content was 36.4%. Phylogenetic analysis of the cp genomes within the Caryophyllaceae family suggests that S. jenisseensis is closer to the clade formed by S. capitata and S. aprica.

The first complete chloroplast (cp) genome of Indofevillea khasiana was reported in this study. The I. khasiana cp genome was 159,238 bp in size, with two inverted repeat (IR) regions of 26,275 bp separated by a large single copy (LSC) region of 88,538 bp and a small single copy (SSC) region of 18,150 bp. The cp genome of this species contained 113 genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The overall GC content was 36.9%. Phylogenetic analysis based on the cp genome sequences suggests that I. khasiana is sister to the rest species of subfam. Cucurbitoideae.

The first complete chloroplast (cp) genome of Hovenia dulcis was reported in this study. The H. dulcis cp genome was 161,636 bp long with two inverted repeat (IR) regions of 26,574 bp, the large single-copy (LSC) region of 89,574 bp, and the small single-copy (SSC) region of 18,914 bp. The cp genome of this species contained 113 genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes. The overall GC content was 36.6%. Phylogenetic analysis based on the complete cp genomes within the Rhamnaceae family suggests that H. dulcis is closer to the genus of Ziziphus.

The first complete chloroplast genome (cp) sequences of Gentiana rhodantha were reported in this study. The cp genome of G. rhodantha was 148,967 bp in size, with two inverted repeat (IR) regions of 25,760 bp, the large single copy (LSC) region of 79,831 bp, and the small single copy (SSC) region of 17,616 bp. The cp genome contained 112 genes, including 78 protein-coding genes, 4 ribosomal RNA, and 30 transfer RNA genes. The overall GC content was 36.4%. Phylogenetic analysis of the cp genomes within the tribe Gentianeae suggests that G. rhodantha is in a sister clade of other subtribe Gentianinae.

Humulus yunnanensis is an endemic species in Yunnan, China, which is used for beer and pharmacology industry. The phylogenetic position of this species in Humulus remains controversial. The complete chloroplast (cp) genome sequence of H. yunnanensis was reported and characterized in this study. The cp genome is 153,612 bp in length and contains a pair of inverted repeats (IRs, 29,824 bp) separated by a large (87,728 bp) and small (15,390 bp) single-copy regions. A total of 112 unique genes were predicted, including 78 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. The phylogenetic analysis revealed that H. yunnanensis is more closely related to H. scandens than H. lupulus.

The complete chloroplast (cp) genome of Pinus squamata, a critically endangered species in China, was reported in this study. The cp genome is 118,300 bp in length and has four regions: 65,298 bp of large single copy (LSC) region and 52,098 bp of small single copy (SSC) region separated by 452 bp of highly reduced inverted repeat (IR) regions. This cp genome with GC content of 38.8% contains 107 unique genes (73 protein-coding genes, 30 tRNA genes, and four rRNA genes). Phylogenetic analysis based on the complete cp genomes indicates that P. squamata is closer to P. gerardiana than P. bungeana.

Ruta graveolens L. is a perennial plant belonging to the family Rutaceae and has been used for traditional medicines for a long time. In this study, the complete chloroplast (cp) genome sequence of R. graveolens was first reported and characterized. The cp genome is 157,434 bp in length and contains a pair of inverted repeats (IRs, 26,868 bp) separated by a large (85,387 bp) and small (18,311 bp) single-copy regions. A total of 132 genes were predicted, including 87 protein-coding genes, 37 tRNA genes and 8 rRNA genes. The phylogenetic analysis suggested that R. graveolens is more closely related to the monophyletic subfam. Aurantioideae.

The complete chloroplast (cp) genome of Magnolia wilsonii, an endangered and endemic species in China, was first reported in this study. The M. wilsonii cp genome was 157,434 bp in length, including two inverted repeat (IR) regions of 26,868 bp, a large single copy (LSC) region of 85,387 bp, and a small single copy (SSC) region of 18,311 bp. A total of 113 unique genes, including 79 protein-coding genes, 4 ribosomal RNA genes, and 30 transfer RNA genes, were annotated. The overall GC content was 38.8%. Phylogenetic analysis of 34 representative cp genomes within the genus Magnolia suggests that M. wilsonii was sister to M. sieboldii.

Paederia scandens has been used as a traditional medicine in Asian countries to treat jaundice, dysentery, and the pain of rheumatism. The complete chloroplast (cp) genome sequence of P. scandens was reported and characterized in this study. The cp genome is 153,626 bp in length, composed of a pair of 26,513 bp inverted repeat (IR) regions separated by a large single-copy (LSC) region of 83,712 bp and a small single-copy (SSC) region of 16,888 bp. There were 131 predicted genes (86 protein-coding genes, 37 tRNA genes, and 8 rRNA genes) in the genome, and the overall GC content of the genome is 37.7%. Phylogenetic analysis based on the cp genome data showed that P. scandens was sister to the clade formed by Galium mollugo and G. aparine.

The complete chloroplast (cp) genome of Rosa berberifolia was assembled from high-throughput Illumina sequencing data. The cp genome of R. berberifolia was 156,886 bp in length with a typical quadripartite circular, containing a pair of inverted repeats (26,047 bp) separated by a large (86,045 bp), and small (18,747 bp) single-copy regions. It contains 129 genes, including 84 protein-coding genes, 8 ribosomal RNA genes, 37 transfer RNA genes, and 1 pseudogene (ycf1). The overall GC content of the whole cp genome was 37.2%. Phylogenetic analysis based on the complete chloroplast genomes suggested that R. berberifolia was sister to R. persica.

The first complete chloroplast (cp) genome of the Chinese endemic and endangered species, Magnolia omeiensis, were reported in this study. The M. omeiensis cp genome was 160,091 bp in length, with two inverted repeat (IR) regions of 26,584 bp, one large single-copy (LSC) region of 88,160 bp, and one small single-copy (SSC) region of 18,763 bp. The cp genome of this species contained 113 unique genes, including 79 protein-coding genes, four ribosomal RNA, and 30 transfer RNA genes. The overall GC content was 39.3%. Phylogenetic analysis of 24 representative cp genomes within the genus Magnolia suggested M. omeiensis is closely related to M. yunnanensis.

A complete picture of the evolution of miRNA combinatorial regulation requires the synthesis of information on all miRNAs and their targets. MiR156 and miR529 are two combinatorial regulators of squamosa promoter binding protein-like (SBP-box) genes. Previous studies have clarified the evolutionary dynamics of their targets; however, there have been no reports on the evolutionary patterns of two miRNA regulators themselves to date. In this study, we investigated the evolutionary differences between these two miRNA families in extant land plants. Our work found that miR529 precursor, especially of its mature miRNA sequence, has a higher evolutionary rate. Such accelerating evolution of miR529 has significantly effects on its structural stability, and sequence conservation against existence of itself. By contrast, miR156 evolves more rapidly in loop region of the stable secondary structure, which may contribute to its functional diversity. Moreover, miR156 and miR529 genes have distinct rates of loss after identical duplication events. MiR529 genes have a higher average loss rate and asymmetric loss rate in duplicated gene pairs, indicating preferred miR529 gene losses become another predominant mode of inactivation, that are implicated in the contraction of this family. On the contrary, duplicated miR156 genes have a low loss rate, and could serve as another new source for functional diversity. Taken together, these results provide better insight into understanding the evolutionary divergence of miR156 and miR529 family in miRNA combinational regulation network.