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In plant tissue culture, differences in endogenous levels of species-specific plant growth regulators (PGRs) may explain differences in regenerative capacity. In the case of polyamines (PAs), their dynamics and distribution may vary between species, genotypes, tissues, and developmental pathways, such as sexual reproduction and apomixis. In this study, for the first time, we aimed to assess the impact of varying endogenous PAs levels in seeds from distinct reproductive modes in Miconia spp. (Melastomataceae), on their in vitro regenerative capacity. We quantified the free PAs endogenous content in seeds of Miconia australis (obligate apomictic), Miconia hyemalis (facultative apomictic), and Miconia sellowiana (sexual) and evaluated their in vitro regenerative potential in WPM culture medium supplemented with a combination of 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BAP). The morphogenic responses were characterized by light microscopy and scanning electron microscopy and discussed regarding the endogenous PAs profiles found. Seeds of M. sellowiana presented approximately eight times more putrescine than M. australis, which was associated with a higher percentage of regenerated calluses (76.67%) than M. australis (5.56%). On the other hand, spermine levels were significantly higher in M. australis. Spermine is indicated as an inhibitor of auxin-carrying gene expression, which may have contributed to its lower regenerative capacity under the tested conditions. These findings provide important insights into in vitro morphogenesis mechanisms in Miconia and highlight the significance of endogenous PA levels in plant regeneration. These discoveries can potentially optimize future regeneration protocols in Miconia, a plant group still underexplored in this area.

A new species, , from riparian environments of the northern Cordillera Oriental of Colombia, is described. This is the second species exclusive to rheophytic conditions that grows in the Andean forest in Colombia and is characterized by the presence of stellate-lepidote trichomes on young structures and inflorescences, terminal inflorescences, 4-merous (rarely 5-merous) flowers, oblong-subulate anthers with an apical pore and 2-locular ovary. The differences with other rheophytic species occurring in Colombia are noted and it is argued that it is related to other Andean species with bluish-green ripe fruits such as and . This new species is so far known only from Colombia and its threat category is suggested as Critically Endangered\" (CR).

Putative processes related to floral diversification and its relation to speciation are still largely unaccounted for in the Melastomataceae. Leandra s.str. is one of the most diverse lineages of the Neotropical Miconieae and ranks among the ten most diverse groups in the Atlantic Forest. Here, we describe the floral diversity of this lineage in a continuous framework and address several questions related to floral evolution and putative developmental and environmental constraints in its morphology. The morphological data set includes individual size measurements and shape scores (from elliptical Fourier analysis) for hypanthia, petals, stamens and styles. We evaluate whether there is evidence of correlation among these floral structures, shifts and convergent patterns, and association of these traits with elevation. Leandra s.str. flower structures present a strong phylogenetic signal and tend to be conserved among close relatives. The extremes in flower regimes seem to be quite distinct, but non-overlapping discrete flower types are not observed. Overall, the morphology of Leandra s.str. floral structures is correlated, and anther colour and inflorescence architecture correlate with flower structures. Additionally, the rates of species diversification and morphological evolution are correlated in most clades. Although some flower regimes tend to occur in different elevational ranges, no significant association is observed. The general idea that hypanthium-ovary fusion is associated with fruit types in the Melastomataceae does not hold for Leandra s.str., where, instead, hypanthium-ovary fusion seems to be associated with anther shape. The lowest rate of flower morphological change, when compared with species diversification rates, is observed in the clade that possesses the most specialized flowers in the group. While stuck on a single general pollination system, Leandra s.str. seems to be greatly wandering around it, given the flower diversity and convergent patterns observed in this group.

Understanding the genetic basis of species differences in flowering time and inflorescence architecture can shed light on speciation and molecular breeding. Melastoma shows rapid speciation, with about 100 species formed in the past few million years, and, meanwhile, possesses high ornamental values. Two largely sympatric and closely related species of this genus, M. candidum and M. normale, differ markedly in flowering time and flower number per inflorescence. Here, we constructed an F2 population between M. candidum and M. normale, and used extreme bulks for flowering time and flower number per inflorescence in this population to identify genomic regions underlying the two traits. We found high differentiation on nearly the whole chromosome 7 plus a few regions on other chromosomes between the two extreme bulks for flowering time. Large chromosomal inversions on chromosome 7 between the two species, which contain flowering-related genes, can explain recombinational suppression on the chromosome. We identified 1872 genes with one or more highly differentiated SNPs between the two bulks for flowering time, including CSTF77, FY, SPA3, CDF3, AGL8, AGL15, FHY1, COL9, CIB1, FKF1 and FAR1, known to be related to flowering. We also identified 680 genes with one or more highly differentiated SNPs between the two bulks for flower number per inflorescence, including PNF, FIL and LAS, knows to play important roles in inflorescence development. These large inversions on chromosome 7 prevent us from narrowing down the genomic region(s) associated with flowering time differences between the two species. Flower number per inflorescence in Melastoma appears to be controlled by multiple genes, without any gene of major effect. Our study indicates that large chromosomal inversions can hamper the identification of the genetic basis of important traits, and the inflorescence architecture of Melastoma species may have a complex genetic basis.

Abstract Although research on gall-associated insects has increased in recent years in Brazil, little is known about this fauna in the Melastomataceae family. Here, we compiled information on the fauna of insects associated with galls induced in species of the Melastomataceae in different Brazilian biomes. Scientific articles on the fauna associated with galls were obtained through the “Web of Science” database. Further, data on associated fauna obtained from the inventories were analyzed and compiled into dynamic tables. To investigate the relationship of inducers with host plants, we performed a network analysis using the 'igraph' R package. We observed 100 insect galls in Melastomataceae, of which only 32 host plant species were identified to the species level and had associated fauna present. The largest number of insect galls was found in the Atlantic Forest (73%) or in Atlantic Forest and Cerrado transition areas (18%). About 52% of the insects belong to the family Cecidomyiidae and 37% of the insects to the order Lepidoptera. Insects belonging to the family Cecidomyiidae induced galls on the following genera Miconia Ruiz and Pav., Tibouchina Aubl. and Leandra Raddi. Besides inducing galls on these same genera, insects of the order Lepidoptera induced galls exclusively on Maieta guianensis Aubl. In short, we found that taxonomic knowledge of the fauna associated with galls in Melastomataceae is very incipient, the distribution of the fauna associated with galls in Brazil is restricted to regions with the presence of specialists in the group. Resumo Embora a pesquisa sobre insetos associados a galhas tenha aumentado nos últimos anos no Brasil, pouco se sabe sobre essa fauna na família Melastomataceae. Aqui, compilamos informações sobre a fauna de insetos associados a galhas induzidas em espécies de Melastomataceae em diferentes biomas brasileiros. Artigos científicos sobre a fauna associada a galhas foram obtidos por meio do banco de dados “Web of Science”. Além disso, dados sobre a fauna associada obtidos dos inventários foram analisados e compilados em tabelas dinâmicas. Para investigar a relação dos indutores com as plantas hospedeiras, realizamos uma análise de rede usando o pacote R 'igraph'. Observamos 100 galhas de insetos em Melastomataceae, das quais apenas 32 espécies de plantas hospedeiras foram identificadas ao nível de espécie e tinham fauna associada presente. O maior número de galhas de insetos foi encontrado na Mata Atlântica (73%) ou em áreas de transição Mata Atlântica e Cerrado (18%). Cerca de 52% dos insetos pertencem à família Cecidomyiidae e 37% dos insetos à ordem Lepidoptera. Insetos pertencentes à família Cecidomyiidae induziram galhas nos seguintes gêneros Miconia Ruiz e Pav., Tibouchina Aubl. e Leandra Raddi. Além de induzir galhas nestes mesmos gêneros, insetos da ordem Lepidoptera induziram galhas exclusivamente em Maieta guianensis Aubl. Em suma, verificamos que o conhecimento taxonômico da fauna associada a galhas em Melastomataceae é muito incipiente, a distribuição da fauna associada a galhas no Brasil é restrita a regiões com presença de especialistas do grupo.

A new species, , from China, is described and illustrated here based on morphological and molecular evidence. It is morphologically similar to in having erect stems, slightly oblique and membranous leaf blades, broadly ovate to suborbicular bracts, and oblong petals, but differs by the terete stems, densely puberulous petioles, and elliptic leaf blades. Our phylogenetic analyses based on plastid genome and nrITS data indicate that this new species is clustered with four species of Yunnan but placed far apart from . An updated key to the genus is also provided.

Aim: We present a new method to economically map gradual changes in plant species composition in lowland rain forests using field data and satellite images. Such a method will be a useful tool in planning the sustainable use and conservation of Amazonian rain forests. Location: The study covered an area of c. 700 km super(2) of primary rain forest in Amazonian Ecuador. Methods: We field inventoried the species composition of pteridophytes and Melastomataceae in 340 inventory plots (5 m x 50 m), described the prevailing topography and analysed soil cation concentration and texture. We used non-metric multidimensional scaling (NMDS) to summarize the floristic variation among the inventory plots in three ordination dimensions. The scores of the three ordination axes were predicted to non-visited places using a Landsat TM (thematic mapper) satellite image and the k nearest neighbours (knn) estimation method. To avoid extrapolation, we excluded from the analysis those pixel windows whose spectral values were not represented in the areas covered by field sampling. The accuracy of the predictions was evaluated by cross-validation and by comparing the predictions based on spectrally nearest neighbours to the predictions based on random neighbours. Results: The floristic gradients presented by NMDS ordination were interpretable in terms of topography, drainage and soil cation content. Thirteen percent of the cloud-free pixels were excluded from the knn analysis to avoid extrapolation. The estimates of the floristic ordination scores based on spectrally nearest neighbours were always more accurate than estimates based on random neighbours. Main conclusions: The presented method needs a relatively small input of work and resources, is mechanistic and produces maps that give relevant information on floristic variation over forest areas that are traditionally considered essentially homogeneous. Therefore, the method appears to have a great potential for use in mapping large areas of Amazonian rain forests.

Natural hybridization plays important roles in plant evolution and speciation. In this study, we sequenced ribosomal internal transcribed spacer (nrITS), four low-copy nuclear genes (Dbr1, SOS4a, SOS4b and PCRF1) and the chloroplast intergenic spacer trnV-trnM to test the hypothesis of hybridization between two species of Phyllagathis and Sporoxeia (Sonerileae/Dissochaeteae, Melastomataceae). Our results provided compelling evidence for the hybridization hypothesis. All hybrid individuals sampled were first-generation hybrids. The failure of flower production in the F1 hybrid individuals may work as the barrier preventing later-generation hybridization or backcross. Analysis of the chloroplast trnV-trnM sequences showed that the hybridization is bidirectional with S. petelotii as the major maternal parent. Several factors, such as sympatry, similar habitat preference, overlapping flowering season and shared pollinators, might have contributed to this hybridization event. The \"intergeneric\" hybridization reported in this study suggests close relationship between P. longicalcarata and S. petelotii.

Thwaites, a heterotypic synonym of Thwaites, is re-instated based on recent collections and field observations. The two species differ mainly in their habit, inflorescence structure, floral morphology and lamina morphology. A lectotype and an epitype are designated for , and a lectotype designated for . Both species are confined to the mixed dipterocarp rainforests of Sri Lanka's perhumid south-western 'wet zone'. appears to be restricted to a relatively small range in Ratnapura district, while has a wider distribution in wet zone.

Floral colour change is a widespread phenomenon in angiosperms, but poorly understood from the genetic and chemical point of view. This article investigates this phenomenon in Pleroma raddianum, a Brazilian endemic species whose flowers change from white to purple. To this end, flavonoid compounds and their biosynthetic gene expression were profiled. By using accurate techniques (Ultra Performance Liquid Chromatography-High-Resolution Mass Spectrometry (UPLC-HRMS)), thirty phenolic compounds were quantified. Five key genes of the flavonoid biosynthetic pathway were partially cloned, sequenced, and the mRNA levels were analysed (RT-qPCR) during flower development. Primary metabolism was also investigated by gas chromatography coupled to mass spectrometry (GC-EIMS), where carbohydrates and organic acids were identified. Collectively, the obtained results suggest that the flower colour change in P. raddianum is determined by petunidin and malvidin whose accumulation coincides with the transcriptional upregulation of early and late biosynthetic genes of the flavonoid pathway, mainly CHS and ANS, respectively. An alteration in sugars, organic acids and phenolic co-pigments is observed together with the colour change. Additionally, an increment in the content of Fe3+ ions in the petals, from the pink to purple stage, seemed to influence the saturation of the colour.