Search Results (9)

Opuntia miquihuanensis (Cactaceae: Opuntioideae), a new species endemic to the locality Peña-Aserradero, part of the Sierra Madre Oriental, Tamaulipas, Mexico, is formally described and illustrated. Phylogenetic analyses used maximum parsimony, maximum likelihood and Bayesian inference, based on sequences of trnL-trnF, psbJ-petA, matK, ycf1, ppc and ITS. The micromorphology of spines, epidermis, stoma, and pollen was characterized with scanning electron microscopy. Opuntia miquihuanensis is recovered as a supported species within Opuntia s.str. Full article

The invasion of Opuntioideae (cacti) was assessed at national, European, and global levels >14 years ago and requires an urgent update. At present, only three species of this subfamily are retained in the official list of the Swiss Federal Bureau of Environment, two of them being potentially invasive. About 550 new observations of Opuntia Mill. and Cylindropuntia (Engelm.) F. M. Knuth in the Swiss Cantons Valais, Vaud, and Ticino have been entered in the Swiss Info Flora database. Our observations include the revision of previously registered and new stations, using a revised taxonomy presented here. Our study covering the last 5 years reveals 12 species, each with a specific ecology. Four species have an invasive potential at a local level in the xeric Central Valais. We characterized the habitat of each species by bedrock and soil type, exposure, and microclimate. Opuntia mesacantha (ex O. humifusa Complex) and O. phaeacantha are currently invasive in the municipality of Sion. Opuntia cymochila (hitherto lumped with O. phaeacantha) is dominant in the municipality of Fully, and Opuntia engelmannii is expanding east of Fully. In Ticino and the Jura foothills, adaptations to 2–3-fold annual precipitation and limestone bedrock are explained by the different soil properties and root systems of Opuntias. Methods of control, in particular, the uprooting currently practiced in Fully and Sion, are discussed. Full article

Tacinga inamoena (K. Schum.) N.P. Taylor & Stuppy (Cactaceae, Opuntioideae) is a native Brazilian species found in the Caatinga phytogeographic domain. Although its flowers are adapted for bird pollination (ornithophily), few birds visit these plants in the ex situ collection at the Rio de Janeiro Botanical Garden. Despite this, fruit production occurs, prompting an investigation into the floral visitors and other animals interacting with T. inamoena flowers. This study aimed to identify floral visitors and quantify florivory damage to flowers in the Cacti and Succulents thematic collection. During the study, 79 flowers were monitored, along with their floral visitors and 26 instances of florivory, totaling 110 observation hours during the anthesis period. Despite recording only five hummingbird visits, a high fruit set was observed, with 72 fruits formed. Results indicated that bees of the genus Trigona sp. were the main floral visitors. Florivory damage, primarily caused by lizards of the species Tropidurus torquatus (Wied-Neuwied, 1820), did not negatively impact fruit formation in this cactus species under cultivation. To fully understand the reproductive success of this species, further studies are needed to assess the viability of seeds formed under these conditions, as the species may be self-compatible and autogamous. Full article

Opuntioideae, composed of roughly 370 species, occur in almost every biome in the Americas, from seasonally dry tropical forests (SDTF) to high-elevation Andean grasslands, American deserts and temperate zones. The interrelationships among the three major clades of Opuntioideae (Cylindropuntieae, Opuntieae and Tephrocacteae) are not well resolved, and thus, the ancestral habitat, biogeographic history and evolution of morphological characters, such as large photosynthetic leaves and flattened stems, are poorly understood. To test their geographic origin and evolution of key morphological characters, we built the largest phylogenomic dataset for Cactaceae to date using 103 plastid genes of 107 taxa of Opuntioideae. The subfamily Opuntioideae likely evolved in South America in a combination of seasonally dry tropical forest (SDTF)/desert habitats. Opuntieae most likely evolved in South America in SDTF and, from there, moved into desert regions, Chaco and temperate/subtropical zones, while Tephrocacteae and Cylindropuntieae evolved in South America in desert regions and moved into SDTF, Chaco and temperate/subtropical zones. Analyses of morphological evolution suggest that, although large leaves are plesiomorphic in Opuntioideae, long-lived, photosynthetically active leaves in Cylindropuntieae and Tephrocacteae are homoplasious and do not represent retained plesiomorphy, as is often assumed. Flattened stems are synapomorphic for Opuntieae, possibly representing adaptation to competition for light resources in SDTF, their most likely ancestral area. Full article

The molecular phylogenies of Cactaceae have enabled us to better understand their systematics, biogeography, and diversification ages. However, most of the phylogenetic relationships within Cactaceae major groups remain unclear, largely due to the lack of an appropriate set of molecular markers to resolve its contentious relationships. Here, we explored the genome and transcriptome assemblies available for Cactaceae and identified putative orthologous regions shared among lineages of the subfamily Cactoideae. Then we developed a probe set, named Cactaceae591, targeting both coding and noncoding nuclear regions for representatives from the subfamilies Pereskioideae, Opuntioideae, and Cactoideae. We also sampled inter- and intraspecific variation to evaluate the potential of this panel to be used in phylogeographic studies. We retrieved on average of 547 orthologous regions per sample. Targeting noncoding nuclear regions showed to be crucial to resolving inter- and intraspecific relationships. Cactaceae591 covers 13 orthologous genes shared with the Angiosperms353 kit and two plastid regions largely used in Cactaceae studies, enabling the phylogenies generated by our panel to be integrated with angiosperm and Cactaceae phylogenies, using these sequences. We highlighted the importance of using coalescent-based species tree approaches on the Cactaceae591 dataset to infer accurate phylogenetic trees in the presence of extensive incomplete lineage sorting in this family. Full article

Opuntia spp. are cacti with high ecological, economic and conservation interest in semiarid environments, particularly in Mexico. We conducted a systematic search of the existing peer-reviewed literature about the state of knowledge of pollination ecology on these plants. We documented the most studied Opuntia species worldwide with an emphasis on Mexico. We found that only 15% of Opuntia species described have been investigated so far, and studies were mainly focused on comprehension of the biology of a single species. Despite the economic and cultural importance of Opuntia, there is a significant lack of knowledge about the flower-visiting insects and their taxonomic identity. We provide a checklist of the insect species associated with Opuntia spp. Through a circular network, we visualize the complex Opuntia flower-visiting insect relationship, and we detected a set of key species constituting the generalist core of the networks constructed. Since pollination is crucial for crop production, a better understanding of ecological interactions would inform management measures to strengthen biodiversity and agriculture sustainability as well as productivity in arid and marginal lands. Further research on pollination ecology is needed to improve the conservation status of the insects associated with Opuntia species. Full article

The Opuntioideae include iconic cacti whose lateral branch–branch junctions are intriguing objects from a mechanical viewpoint. We have compared Opuntia ficus-indica, which has stable branch connections, with Cylindropuntia bigelovii, whose side branches abscise under slight mechanical stress. To determine the underlying structures and mechanical characteristics of these stable versus shedding cacti junctions, we conducted magnetic resonance imaging, morphometric and anatomical analyses of the branches and tensile tests of individual tissues. The comparison revealed differences in geometry, shape and material properties as follows: (i) a more pronounced tapering of the cross-sectional area towards the junctions supports the abscission of young branches of C. bigelovii. (ii) Older branches of O. ficus-indica form, initially around the branch–branch junctions, collar-shaped periderm tissue. This secondary coverage mechanically stiffens the dermal tissue, giving a threefold increase in strength and a tenfold increase in the elastic modulus compared with the epidermis. (iii) An approximately 200-fold higher elastic modulus of the vascular bundles of O. ficus-indica is a prerequisite for the stable junction of its young branches. Our results provide, for both biological and engineered materials systems, important insights into the geometric characteristics and mechanical properties of branching joints that are either stable or easily detachable. Full article

Damage-repair is particularly important for the maintenance of the water-storing abilities of succulent plants such as cacti. Comparative morphological, anatomical, and biomechanical analyses of self-repair were performed on artificially wounded branches of Opuntia ficus-indica and Cylindropuntia bigelovii. Macroscopic observations, contrast staining, and lignin-proof staining were used to investigate morphological and anatomical responses after wounding at various time intervals. Two-point bending tests were repeatedly performed on the same branches under unwounded, freshly wounded, and healed conditions by using customized 3D-printed clamping jaws. Morphologically, both species showed a rolling-in of the wound edges, but no mucilage discharge. Anatomically, ligno-suberized peridermal layers developed that covered the wound region, and new parenchyma cells formed, especially in O. ficus-indica. In all samples, the wounding effect directly after damage caused a decrease between 18% and 37% in all the tested mechanical parameters, whereas a positive healing effect after 21 days was only found for C. bigelovii. Based on our data, we hypothesize a high selection pressure on the restoration of structural integrity in the wound area, with a focus on the development of efficient water-retaining mechanisms, whereas the concept of “sufficient is good enough” seems to apply for the restoration of the mechanical properties. Full article

Cactaceae comprise a diverse and iconic group of flowering plants which are almost exclusively indigenous to the New World. The wide variety of growth forms found amongst the cacti have led to the trafficking of many species throughout the world as ornamentals. Despite the evolution and physiological properties of these plants having been extensively studied, little research has focused on cactus-associated viral communities. While only single-stranded RNA viruses had ever been reported in cacti, here we report the discovery of cactus-infecting single-stranded DNA viruses. These viruses all apparently belong to a single divergent species of the family Geminiviridae and have been tentatively named Opuntia virus 1 (OpV1). A total of 79 apparently complete OpV1 genomes were recovered from 31 different cactus plants (belonging to 20 different cactus species from both the Cactoideae and Opuntioideae clades) and from nine cactus-feeding cochineal insects (Dactylopius sp.) sampled in the USA and Mexico. These 79 OpV1 genomes all share > 78.4% nucleotide identity with one another and < 64.9% identity with previously characterized geminiviruses. Collectively, the OpV1 genomes display evidence of frequent recombination, with some genomes displaying up to five recombinant regions. In one case, recombinant regions span ~40% of the genome. We demonstrate that an infectious clone of an OpV1 genome can replicate in Nicotiana benthamiana and Opuntia microdasys. In addition to expanding the inventory of viruses that are known to infect cacti, the OpV1 group is so distantly related to other known geminiviruses that it likely represents a new geminivirus genus. It remains to be determined whether, like its cactus hosts, its geographical distribution spans the globe. Full article