Biology subjects

Majure, L. C.

Publications and source records attributed to Majure, L. C..

4 recordsLinked to original sources

bioRxiv2023

More than a prickly morphology: plastome variation in the prickly pear cacti (Opuntieae)

Plastid genomes (plastomes) have long been recognized as highly conserved in their overall structure, size, gene arrangement and content among land plants. However, recent studies have shown that some lineages present unusual variations in some of these features. Members of the cactus family are one of these lineages, with distinct plastome structures reported across disparate lineages including gene losses, inversions, boundary movements, or loss of the canonical inverted repeat (IR) region. Here, we further investigated plastome features of the tribe Opuntieae, the remarkable prickly pear cacti, which represent a diverse and important lineage of Cactaceae. We assembled the plastome of 43 species, representing a comprehensive sampling of the tribe including all seven genera. Plastomes varied considerably in length from 121 kbp to 162 kbp, with striking differences in the content and size of the IR region (contraction and expansion events), including the lack of the canonical IR in some lineages, and the pseudogenization or loss of some genes. Overall, nine different types of plastomes were reported deviating in the presence of the IR region or the genes contained in the IR. Plastomes sequences resolved phylogenetic relationships within major clades of Opuntieae but presented some contentious nodes depending on the data set analyzed (e.g., whole plastome vs. genes only). Incongruence analyses revealed that few plastome regions are supporting the most likely topology, while disputing topologies are driven by a handful of plastome markers, which may be the result of hard recalcitrant nodes in the phylogeny or by the lack of phylogenetic signal in certain markers. Our study reveals a dynamic nature of plastome evolution across closely related lineages, shedding light on peculiar features of cactus plastomes. Variation of plastome types across Opuntieae is remarkable in size, structure, and content, and can be important for the recognition of species in some major clades. Unraveling connections between the causes of plastome variation and the consequences on species biology, ecology, diversification, and adaptation, is a promising endeavor.

plant biology↗

bioRxiv2020

Insights into chloroplast genome variation across Opuntioideae (Cactaceae)

Chloroplast genomes (plastomes) are frequently treated as highly conserved among land plants. However, many lineages of vascular plants have experienced extensive structural rearrangements, including inversions and modifications to the size and content of genes. Cacti are one of these lineages, containing the smallest plastome known for an obligately photosynthetic angiosperm, including the loss of one copy of the inverted repeat ([~]25 kb) and the ndh genes suite, but only a few cacti from the subfamily Cactoideae have been sufficiently characterized. Here, we investigated the variation of plastome sequences across the second-major lineage of the Cactaceae, the subfamily Opuntioideae, to address 1) how variable is the content and arrangement of chloroplast genome sequences across the subfamily, and 2) how phylogenetically informative are the plastome sequences for resolving major relationships among the clades of Opuntioideae. Our de novo assembly of the Opuntia quimilo plastome recovered an organelle of 150,347 bp in length with both copies of the inverted repeats and the presence of all the ndh genes suite. An expansion of the large single copy unit and a reduction of the small single copy was observed, including translocations and inversion of genes as well as the putative pseudogenization of numerous loci. Comparative analyses among all clades within Opuntioideae suggested that plastome structure and content vary across taxa of this subfamily, with putative independent losses of the ndh gene suite and pseudogenization of genes across disparate lineages, further demonstrating the dynamic nature of plastomes in Cactaceae. Our plastome dataset was robust in determining relationships among major clades and subclades within Opuntioideae, resolving three tribes with high support: Cylindropuntieae, Tephrocacteae and Opuntieae. A plastome-wide survey for highly informative phylogenetic markers revealed previously unused regions for future use in Sanger-based studies, presenting a valuable dataset with primers designed for continued evolutionary studies across Cactaceae. These results bring new insights into the evolution of plastomes in cacti, suggesting that further analyses should be carried out to address how ecological drivers, physiological constraints and morphological traits of cacti may be related with the common rearrangements in plastomes that have been reported across the family.

evolutionary biology↗

bioRxiv2020

Beyond endemism, expanding conservation efforts: a relictual Pleistocene distribution and first report of the prickly pear cactus, Opuntia bonaerensis, in Brazil and Uruguay

Geographical range is one of the critical features for species conservation assessment. Nevertheless, species distribution is frequently unknown, undervalued or overlooked. During a broad taxonomic and floristic study of the southern South American prickly pear species (Opuntia spp.), new records of a previously endemic Argentinian taxon have been found in Uruguay and Brazil. Molecular phylogenetic inference was carried out to further evaluate the identity of the new records, and ecological niche models were implemented to test how the new records would fit in the previous known distribution of the species. Through molecular and morphological evidence, we confirmed the new records of Opuntia bonaerensis for Brazilian and Uruguayan floras and discussed its phylogenetic relationship and morphologic similarities with closely related species. Our new records uncovered a distributional pattern congruent with the Neotropical Peripampasic Orogenic Arc, which must be further explored to better determine the biogeographic history of the species. Ecological niche models (ENM) revealed that O. bonaerensis had a putative ancient distribution across the grasslands and shrublands in the Pampean region largely congruent with the populations found in Brazil and Uruguay, suggesting relictual Pleistocene populations of the species and the role of glacial/interglacial cycles on the distribution of the species. In a prospective climate change scenario, ENM suggests that the species would in general be more restricted to the southernmost limits of the Pampa region and previous outlying records from Mendoza (Argentina) are a putative future refuge for O. bonaerensis. The importance of these new records for biodiversity and conservation assessment efforts that are ongoing at different scales in Brazil and neighbor areas is highlighted.

plant biology↗

bioRxiv2020

Reassessment and typification of Opuntia canterae (Opuntioideae, Cactaceae), an endemic prickly-pear cactus of Uruguay

Background and aimsOpuntia is the most widespread genus of Cactaceae, naturally occurring throughout arid and semi-arid areas of the Americas. Many of the species have taxonomic problems owed to incomplete original descriptions, lack of type designations, a paucity of taxonomic revisions and in general, difficult species delimitation resulting from hybridization, morphological plasticity and poor specimen preparation. However, efforts are being undertaken to fill in the gaps in our distributional, morphological and phylogenetic knowledge of the group. Here, we reassess the name Opuntia canterae, providing an updated description, typification, photographs, distribution map, conservation assessment and additional notes. Material and methodsExtensive fieldwork was conducted, along with comprehensive herbarium and literature review. Morphological characters were assessed based on the commonly used characters used for prickly pears. Species delimitation is proposed based on our morphological studies, taxonomic and literature revision, as well as preliminary phylogenetic studies. The IUCN guidelines were followed to provide a conservation assessment of the species. Key resultsOpuntia canterae is reassessed as a distinct species separated from its previous synonym (O. elata) by the elliptic to long-oblanceolate stem segments, acute to conical flower bud apex and long-obconic fruits. An epitype is here designate for purposes of the precise designation of the name to the taxon. The species is considered endemic to Uruguay and is assessed as Vulnerable (VU) using IUCN criteria, but more fieldwork will be necessary to provide a more precise conservation status.

plant biology↗