Pleistocene climate oscillations have shaped the expansion and contraction speciation model of the globose Eriosyce sect. Neoporteria cacti in Central Chile.

BACKGROUND AND AIMS: Pleistocene climatic oscillations, characterized by arid (interglacial) and pluvial (glacial) phases, have profoundly impacted the floras of Mediterranean climates. Our study investigates the hypothesis that these climatic extremes have promoted phases of range expansion and contraction in the Eriosyce sect. Neoporteria, resulting in pronounced genetic structuring and restricted gene flow. METHODS: Utilizing nuclear microsatellite markers, we genotyped 251 individuals across 18 populations, encompassing all 14 species and one subspecies within the Eriosyce sect. Neoporteria. Additionally, Species Distribution Models (SDMs) were employed to reconstruct past (Last Interglacial, Last Glacial Maximum, Mid-Holocene) and current potential distribution patterns, aiming to delineate the climatic influences on species' range dynamics. KEY RESULTS: The gene flow analysis disclosed disparate levels of genetic interchange among species, with marked restrictions observed between entities that are geographically or ecologically separated. Notably, E. subgibbosa from Hualpen emerged as genetically distinct, warranting its exclusion for clearer genetic clustering into north, central, and south clusters. The SDMs corroborated these findings, showing marked range expansions during warmer periods and contractions during colder times, indicating significant shifts in distribution patterns in response to climatic changes. CONCLUSIONS: Our findings emphasize the critical role of Pleistocene climatic fluctuations in driving the dynamic patterns of range expansions and contractions that have led to geographic isolation and speciation within the Eriosyce sect. Neoporteria. Even in the face of ongoing gene flow, these climate-driven processes have played a pivotal role in sculpting the species' genetic architecture and diversity. This study elucidates the complex interplay between climatic variability and evolutionary dynamics among Mediterranean cacti in central Chile, highlighting the necessity of considering historical climatic millenial oscillations in conservation and evolutionary biology studies.

Effect of BvAgNP on growth, development, and glyoxalase gene expression analysis in Mammillaria bombycina and Selenicereus undatus.

BACKGROUND: Silver nanoparticles (AgNPs) have been used in plant tissue culture as growth stimulants, promoting bud initiation, germination, and rooting. In prior studies, AgNPs were synthesized and characterized by green synthesis using extracts from Beta vulgaris var. cicla (BvAgNP), and their functionality as seed disinfectant and antimicrobial was verified. In this study, we evaluated the effect of BvAgNP on the growth and development of Mammillaria bombycina and Selenicereus undatus in vitro, as well as the expression of glyoxalase genes. METHODS: Explants from M. bombycina and S. undatus in vitro were treated with 25, 50, and 100 mg/L of BvAgNP. After 90 days, morphological characteristics were evaluated, and the expression of glyoxalase genes was analyzed by qPCR. RESULTS: All treatments inhibited rooting for M. bombycina and no bud initiation was observed. S. undatus, showed a maximum response in rooting and bud generation at 25 mg/L of BvAgNP. Scanning electron microscopy (SEM) results exhibited a higher number of vacuoles in stem cells treated with BvAgNP compared to the control for both species. Expression of glyoxalase genes in M. bombycina increased in all treatments, whereas it decreased for S. undatus, however, increasing in roots. CONCLUSIONS: This study presents the effects of BvAgNP on the growth and development of M. bombycina and S. undatus, with the aim of proposing treatments that promote in vitro rooting and bud initiation.

The plastomes of Lepismium cruciforme (Vell.) Miq and Schlumbergera truncata (Haw.) Moran reveal tribe-specific rearrangements and the first loss of the trnT-GGU gene in Cactaceae.

BACKGROUND: Recent studies have revealed atypical features in the plastomes of the family Cactaceae, the largest lineage of succulent species adapted to arid and semi-arid regions. Most plastomes sequenced to date are from short-globose and cylindrical cacti, while little is known about plastomes of epiphytic cacti. Published cactus plastomes reveal reduction and complete loss of IRs, loss of genes, pseudogenization, and even degeneration of tRNA structures. Aiming to contribute with new insights into the plastid evolution of Cactaceae, particularly within the tribe Rhipsalideae, we de novo assembled and analyzed the plastomes of Lepismium cruciforme and Schlumbergera truncata, two South American epiphytic cacti. METHODS AND RESULTS: Our data reveal many gene losses in both plastomes and the first loss of functionality of the trnT-GGU gene in Cactaceae. The trnT-GGU is a pseudogene in L. cruciforme plastome and appears to be degenerating in the tribe Rhipsalideae. Although the plastome structure is conserved among the species of the tribe Rhipsalideae, with tribe-specific rearrangements, we mapped around 200 simple sequence repeats and identified nine nucleotide polymorphism hotspots, useful to improve the phylogenetic resolutions of the Rhipsalideae. Furthermore, our analysis indicated high gene divergence and rapid evolution of RNA editing sites in plastid protein-coding genes in Cactaceae. CONCLUSIONS: Our findings show that some characteristics of the Rhipsalideae tribe are conserved, such as plastome structure with IRs containing only the ycf2 and two tRNA genes, structural degeneration of the trnT-GGU gene and ndh complex, and lastly, pseudogenization of rpl33 and rpl23 genes, both plastid translation-related genes.

Influence of the nurse-protégé interaction on the frugivory pattern of the columnar cactus Pilosocereus leucocephalus.

Nurse plants provide benefits during the early life cycle of the protected plant by reducing the intensity of stressful abiotic conditions. However, nurse plants may influence frugivore visitation and consumption, affecting the initial benefits of this interaction and generating different frugivory patterns during the reproductive phase of the protégé. Despite the importance of nurse plants and frugivory in the structure and composition of ecosystems, they have rarely been evaluated together, and frugivory patterns caused by nurse plants at different spatial and temporal scales are mostly unknown. Pilosocereus leucocephalus produces seeds that are endozoochorically dispersed by birds and mammals, can establish in open spaces devoid of arboreal vegetation (OS), and is associated with the nurse tree Lysiloma acapulcensis. However, the influence of L. acapulcensis on the frugivory patterns of P. leucocephalus is unknown. Therefore, during the fruiting season of P. leucocephalus of 2018, we recorded the visitation rates, effective removal, and removal timescales in 26 individuals located in OS and 15 under L. acapulcensis. Our results indicate that L. acapulcensis increased visits by Euphonia hirundinacea and bats but decreased those of Psilorhinus morio and Campylorhynchus rufinucha. Although L. acapulcensis did not generate differences in fruit removal effectiveness, bats showed the highest effectiveness in OS, followed by birds. L. acapulcensis also had an effect on the fruit removal periods of different frugivorous species at different temporal scales. This shows that the nurse tree generated a complex pattern of frugivory in P. leucocephalus, mainly increasing the initial benefits of the nurse-protégé interaction.

Pulmonary surfactant protein B carried by HDL predicts incident CVD in patients with type 1 diabetes.

Atherosclerotic CVD is the major cause of death in patients with type 1 diabetes mellitus (T1DM). Alterations in the HDL proteome have been shown to associate with prevalent CVD in T1DM. We therefore sought to determine which proteins carried by HDL might predict incident CVD in patients with T1DM. Using targeted MS/MS, we quantified 50 proteins in HDL from 181 T1DM subjects enrolled in the prospective Coronary Artery Calcification in Type 1 Diabetes study. We used Cox proportional regression analysis and a case-cohort design to test associations of HDL proteins with incident CVD (myocardial infarction, coronary artery bypass grafting, angioplasty, or death from coronary heart disease). We found that only one HDL protein-SFTPB (pulmonary surfactant protein B)-predicted incident CVD in all the models tested. In a fully adjusted model that controlled for lipids and other risk factors, the hazard ratio was 2.17 per SD increase of SFTPB (95% confidence interval, 1.12-4.21, P = 0.022). In addition, plasma fractionation demonstrated that SFTPB is nearly entirely bound to HDL. Although previous studies have shown that high plasma levels of SFTPB associate with prevalent atherosclerosis only in smokers, we found that SFTPB predicted incident CVD in T1DM independently of smoking status and a wide range of confounding factors, including HDL-C, LDL-C, and triglyceride levels. Because SFTPB is almost entirely bound to plasma HDL, our observations support the proposal that SFTPB carried by HDL is a marker-and perhaps mediator-of CVD risk in patients with T1DM.

Evolution of flower allometry and pigmentation in Mammillaria haageana (Cactaceae).

BACKGROUND: A puzzle in evolution is the understanding of how the environment might drive subtle phenotypic variation, and whether this variation is adaptive. Under the neutral evolutionary theory, subtle phenotypes are almost neutral with little adaptive value. To test this idea, we studied the infraspecific variation in flower shape and color in Mammillaria haageana, a species with a wide geographical distribution and phenotypic variation, which populations are often recognized as infraspecific taxa. RESULTS: We collected samples from wild populations, kept them in the greenhouse for at least one reproductive year, and collected newly formed flowers. Our first objective was to characterize tepal natural variation in M. haageana through geometric morphometric and multivariate pigmentation analyses. We used landmark-based morphometrics to quantify the trends of shape variation and tepal color-patterns in 20 M. haageana accessions, belonging to five subspecies, plus 8 M. albilanata accessions for comparison as the sister species. We obtained eight geometric morphometric traits for tepal shape and color-patterns. We found broad variation in these traits between accessions belonging to the same subspecies, without taxonomic congruence with those infraspecific units. Also the phenetic cluster analysis showed different grouping patterns among accessions. When we correlated these phenotypes to the environment, we also found that solar radiation might explain the variation in tepal shape and color, suggesting that subtle variation in flower phenotypes might be adaptive. Finally we present anatomical sections in M. haageana subsp. san-angelensis to propose some of the underlying tepal structural features that may give rise to tepal variation. CONCLUSIONS: Our geometric morphometric approach of flower shape and color allowed us to identify the main trends of variation in each accession and putative subspecies, but also allowed us to correlate these variation to the environment, and propose anatomical mechanisms underlying this diversity of flower phenotypes.

Impact of the Cooking Process on Metabolite Profiling of Acanthocereus tetragonus, a Plant Traditionally Consumed in Mexico.

Acanthocereus tetragonus (L.) Hummelinck is used as an alternative food source in some Mexican communities. It has been shown that the young stems of A. tetragonus provide crude protein, fiber, and essential minerals for humans. In this work, we analyzed the phytochemical profile, the total phenolic content (TPC), and the antioxidant activity of cooked and crude samples of A. tetragonus to assess its functional metabolite contribution to humans. The phytochemical profile was analyzed using Ultra-High-Performance Liquid Chromatography coupled to High-Resolution Mass Spectrometry (UHPLC-PDA-HESI-Orbitrap-MS/MS). Under the proposed conditions, 35 metabolites were separated and tentatively identified. Of the separated metabolites, 16 occurred exclusively in cooked samples, 6 in crude samples, and 9 in both crude and cooked samples. Among the detected compounds, carboxylic acids, such as threonic, citric, and malic acids, phenolic acids, and glycosylated flavonoids (luteolin-O-rutinoside) were detected. The TPC and antioxidant activity were analyzed using the Folin-Ciocalteu method and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical inhibition method, respectively. The TPC and antioxidant activity were significantly reduced in the cooked samples. We found that some metabolites remained intact after the cooking process, suggesting that A. tetragonus represents a source of functional metabolites for people who consume this plant species.

Cacti as low-cost substrates to produce L-asparaginase by endophytic fungi.

This study aimed to select endophytic fungi to produce L-asparaginase and partially optimising the production of the enzyme using cacti as substrate. Seventeen endophytes were assessed for intracellular enzymatic potential in modified Czapek Dox's medium using L-proline as an inducer. The best producer was evaluated for intracellular and extracellular enzymatic activity in modified Czapek Dox's medium using flours of Opuntia ficus-indica and Nopalea cochenillifera as substrate. The biomass and L-asparaginase production profile was analysed and the best conditions for enzyme production were verified using factorial design. Penicillium decaturense URM 7966, Diaporthe ueckerae URM 8321, and Colletotrichum annellatum URM 8538 produced 0.76 U g- 1, 0.87 U g- 1, and 0.74 U g- 1 L-asparaginase, respectively. Diaporthe ueckerae URM 8321 produced only intracellular L-asparaginase, using flours of N. cochenillifera (0.72 U g- 1) and O. ficus-indica (0.90 U g- 1) and the last was selected for the next steps. The ideal time for biomass and L-asparaginase production was 120 h. The best conditions for enzyme production (1.67 U g- 1) were initial pH 4.0, inoculum concentration 1% and cacti flour concentration 0.2%; where was observed an increase of 46.11% in compared to the initial production. Opuntia ficus-indica flour is indicated as an alternative low-cost substrate for the production of L-asparaginase by the endophytic fungus D. ueckerae URM 8321.

Fusarium: more than a node or a foot-shaped basal cell.

Recent publications have argued that there are potentially serious consequences for researchers in recognising distinct genera in the terminal fusarioid clade of the family Nectriaceae. Thus, an alternate hypothesis, namely a very broad concept of the genus Fusarium was proposed. In doing so, however, a significant body of data that supports distinct genera in Nectriaceae based on morphology, biology, and phylogeny is disregarded. A DNA phylogeny based on 19 orthologous protein-coding genes was presented to support a very broad concept of Fusarium at the F1 node in Nectriaceae. Here, we demonstrate that re-analyses of this dataset show that all 19 genes support the F3 node that represents Fusarium sensu stricto as defined by F. sambucinum (sexual morph synonym Gibberella pulicaris). The backbone of the phylogeny is resolved by the concatenated alignment, but only six of the 19 genes fully support the F1 node, representing the broad circumscription of Fusarium. Furthermore, a re-analysis of the concatenated dataset revealed alternate topologies in different phylogenetic algorithms, highlighting the deep divergence and unresolved placement of various Nectriaceae lineages proposed as members of Fusarium. Species of Fusarium s. str. are characterised by Gibberella sexual morphs, asexual morphs with thin- or thick-walled macroconidia that have variously shaped apical and basal cells, and trichothecene mycotoxin production, which separates them from other fusarioid genera. Here we show that the Wollenweber concept of Fusarium presently accounts for 20 segregate genera with clear-cut synapomorphic traits, and that fusarioid macroconidia represent a character that has been gained or lost multiple times throughout Nectriaceae. Thus, the very broad circumscription of Fusarium is blurry and without apparent synapomorphies, and does not include all genera with fusarium-like macroconidia, which are spread throughout Nectriaceae (e.g., Cosmosporella, Macroconia, Microcera). In this study four new genera are introduced, along with 18 new species and 16 new combinations. These names convey information about relationships, morphology, and ecological preference that would otherwise be lost in a broader definition of Fusarium. To assist users to correctly identify fusarioid genera and species, we introduce a new online identification database, Fusarioid-ID, accessible at www.fusarium.org. The database comprises partial sequences from multiple genes commonly used to identify fusarioid taxa (act1, CaM, his3, rpb1, rpb2, tef1, tub2, ITS, and LSU). In this paper, we also present a nomenclator of names that have been introduced in Fusarium up to January 2021 as well as their current status, types, and diagnostic DNA barcode data. In this study, researchers from 46 countries, representing taxonomists, plant pathologists, medical mycologists, quarantine officials, regulatory agencies, and students, strongly support the application and use of a more precisely delimited Fusarium (= Gibberella) concept to accommodate taxa from the robust monophyletic node F3 on the basis of a well-defined and unique combination of morphological and biochemical features. This F3 node includes, among others, species of the F. fujikuroi, F. incarnatum-equiseti, F. oxysporum, and F. sambucinum species complexes, but not species of Bisifusarium [F. dimerum species complex (SC)], Cyanonectria (F. buxicola SC), Geejayessia (F. staphyleae SC), Neocosmospora (F. solani SC) or Rectifusarium (F. ventricosum SC). The present study represents the first step to generating a new online monograph of Fusarium and allied fusarioid genera (www.fusarium.org).

Smells from the desert: Microbial volatiles that affect plant growth and development of native and non-native plant species.

The plant microbiota can affect host fitness via the emission of microbial volatile organic compounds (mVOCs) that influence growth and development. However, evidence of these molecules and their effects in plants from arid ecosystems is limited. We screened the mVOCs produced by 40 core and representative members of the microbiome of agaves and cacti in their interaction with Arabidopsis thaliana and Nicotiana benthamiana. We used SPME-GC-MS to characterize the chemical diversity of mVOCs and tested the effects of selected compounds on growth and development of model and host plants. Our study revealed that approximately 90% of the bacterial strains promoted plant growth both in A. thaliana and N. benthamiana. Bacterial VOCs were mainly composed of esters, alcohols, and S-containing compounds with 25% of them not previously characterized. Remarkably, ethyl isovalerate, isoamyl acetate, 3-methyl-1-butanol, benzyl alcohol, 2-phenylethyl alcohol, and 3-(methylthio)-1-propanol, and some of their mixtures, displayed beneficial effects in A. thaliana and also improved growth and development of Agave tequilana and Agave salmiana in just 60 days. Volatiles produced by bacteria isolated from agaves and cacti are promising molecules for the sustainable production of crops in arid and semi-arid regions.

Undervalued potential of crassulacean acid metabolism for current and future agricultural production.

The potential for crassulacean acid metabolism (CAM) to support resilient crops that meet demands for food, fiber, fuel, and pharmaceutical products far exceeds current production levels. This review provides background on five families of plants that express CAM, including examples of many species within these families that have potential agricultural uses. We summarize traditional uses, current developments, management practices, environmental tolerance ranges, and economic values of CAM species with potential commercial applications. The primary benefit of CAM in agriculture is high water use efficiency that allows for reliable crop yields even in drought conditions. Agave species, for example, grow in arid conditions and have been exploited for agricultural products in North and South America for centuries. Yet, there has been very little investment in agricultural improvement for most useful Agave varieties. Other CAM species that are already traded globally include Ananas comosus (pineapple), Aloe spp., Vanilla spp., and Opuntia spp., but there are far more with agronomic uses that are less well known and not yet developed commercially. Recent advances in technology and genomic resources provide tools to understand and realize the tremendous potential for using CAM crops to produce climate-resilient agricultural commodities in the future.

A decade of flowering phenology of the keystone saguaro cactus (Carnegiea gigantea).

PREMISE OF THE STUDY: Phenology is the study of biological life cycle events, such as flowering and migration. Climate patterns can alter these life history events, having ecosystem-wide ramifications. For example, warmer springs are associated with earlier leaf-out for many species, impacting species interactions and growing-season carbon dynamics. While phenological research has been conducted extensively in temperate regions, relatively little is known about the phenological responses in arid and semi-arid regions. METHODS: In this study we looked at the flowering phenology of a keystone species in the Sonoran Desert, the saguaro cactus (Carnegiea gigantea). The timing and abundance of flowering was observed on 151 individuals for 10 years at a site near Tucson, Arizona, USA. Using six phenological traits, we explored the relationship between saguaro size and flowering and the climatic drivers of flowering. KEY RESULTS: Our analyses demonstrated how the calculation of phenological traits at the individual versus the population level can yield differing responses to climate variability, suggesting that not all studies examining the same trait (e.g., first day of bloom) are directly comparable. We found that larger cacti began flowering earlier, flowered for longer, and produced more flowers. Warmer temperatures were correlated with advanced onset and higher bloom yields, while increased precipitation appeared to delay onset and reduce bloom yields. CONCLUSIONS: Given that climate models predict that the Southwestern USA will become increasingly warmer with more variable precipitation, saguaros may begin flowering earlier in the season and flower more intensely, which could impact pollen availability and population dynamics.

Cacti for production of metabolites: current state and perspectives.

The Cactaceae family is native from the American continent but is distributed in the arid and semiarid regions worldwide. Cacti exhibit different morphological (succulent body, extended root system, presence of spines, thick waterproof epidermis) and physiological adaptations (crassulacean acid metabolism) that allow growth in adverse conditions intolerable for most C3 and C4 crops. In addition, these plants produce a wide range of secondary metabolites involved in defense mechanism against biotic and abiotic stresses. The present review focused on the content of alkaloids, phenolic compounds, and terpenes present in cacti plants. Data were limited to those compounds clearly characterized by chromatographic and/or spectrometric techniques in both globular and columnar cacti. Additional information about their pharmacological or biological activities, validated by in vitro or in vivo assays, is also presented. Data revealed that the level of some chemical constituents could give value added to these species from a nutritional, pharmacological, and biological point of view.

Quantitative and qualitative traits of carcass and meat of goats fed diets with cactus meal replacing corn.

The purpose of this study was to evaluate the quantitative and qualitative characteristics of the carcass and meat of goats fed diets containing cactus meal (pectin source) replacing corn (starch source). Twenty-eight goats with an average initial weight of 16 ± 2.02 kg were confined in a completely randomized design with four treatments (the replacement levels of 0, 330, 660, and 1000 g kg-1 of dry matter) and seven replicates. The productive performance of the animals was not affected by the replacement of corn by cactus meal. The carcass commercial yield and the dressing percentage decreased with the addition of cactus meal levels in the diets. The commercial cuts, however, especially prime cuts like hind limbs and loin, were not changed by the use of cactus meal. Muscle:bone and fat:bone ratios and muscularity index of hind limbs were influenced by the substitution. The protein and ash contents of the longissimus lumborum muscle decreased while cholesterol levels increased with the presence of cactus meal. Sensory traits of goats' meat fed cactus meal in the diets were not affected. The substitution of corn for cactus meal reduced carcass yield but did not change the yield of commercial cuts or the qualitative characteristics of the meat.

Ruminal and morphometric parameters of the rumen and intestines of sheep fed with increasing levels of spineless cactus (Nopalea cochenillifera Salm-Dyck).

The objective of this study was to evaluate the ruminal parameters (pH, N-NH3, and microbial protein) and morphometry of the rumen and intestine of sheep fed with a diet containing four different levels of the spineless cactus variety, Baiana. The experiment was conducted at the National Semi-Arid Institute in Campina Grande, PB, Brazil. A total of 40 male sheep submitted to the confinement regime were used in a completely randomized design with four treatments (0, 15, 30, and 45% dry matter basis) and ten replicates, with an initial body weight of 23.7 ± 3.08 kg. Experimental diets were composed of ground corn, soybean meal, urea, mineral supplement, limestone, Tifton 85 hay, and spineless cactus of the Baiana variety. The pH, ammonia nitrogen, and microbial protein were evaluated in the ruminal fluid, alongside the morphometric characteristics of the rumen and intestine. While the addition of the spineless cactus did not affect N-NH3, it caused a linear reduction in the ruminal pH following 4 h of feeding, and also increased the microbial protein. In addition, it stimulated a reduction in the height of the papillae and the muscle layer of the rumen, and induced the mucosal height in the intestine to increase. The addition of up to 30% of spineless cactus in the diet of sheep without a defined breed did not alter the N-NH3, pH, and ruminal histology, but it did increase the production of microbial protein and intestinal mucosa.

Studies on the Biology of Hypogeococcus pungens (sensu stricto) (Hemiptera: Pseudococcidae) in Argentina to Aid the Identification of the Mealybug Pest of Cactaceae in Puerto Rico.

Hypogeococcus pungens Granara de Willink, sensu stricto, is a serious pest of cacti in Puerto Rico threating many Caribbean islands. A classical biological control program for H. pungens was initiated for Puerto Rico in 2010 with a survey for natural enemies of H. pungens in its native range of Argentina. Biological differences were observed between populations of H. pungens sampled on Amaranthaceae and Cactaceae. Molecular studies suggested that H. pungens populations from different host plant families are likely a complex of species. Our objective was to study the biology of H. pungens sensu stricto on specimens collected in the same locality and host plant as the holotype [Tucumán Province, Argentina; Alternanthera pungens Kunth (Amaranthaceae)]. We were interested in the reproductive biology of females, longevity and survival of adults, the effect of temperature on the development, and nymph performance (survival and development) on five Cactaceae species. We found that H. pungens s.s showed marked biological differences from the populations collected on Cactaceae and exported to Australia for the biological control of the cactus Harrisia spp. The main differences were the presence of deuterotoky parthenogenesis and the fact that H. pungens did not attack Cactaceae in the laboratory. Our results provide biological evidence that H. pungens is a species complex. We propose that the population introduced to Australia is neither Hypogeococcus festerianus Lizer y Trelles nor H. pungens, but an undescribed species with three circuli, and that the Hypogeococcus pest of cacti in Puerto Rico is not H. pungens.

Exceptional reduction of the plastid genome of saguaro cactus (Carnegiea gigantea): Loss of the ndh gene suite and inverted repeat.

UNLABELLED: • PREMISE OF THE STUDY: Land-plant plastid genomes have only rarely undergone significant changes in gene content and order. Thus, discovery of additional examples adds power to tests for causes of such genome-scale structural changes.• METHODS: Using next-generation sequence data, we assembled the plastid genome of saguaro cactus and probed the nuclear genome for transferred plastid genes and functionally related nuclear genes. We combined these results with available data across Cactaceae and seed plants more broadly to infer the history of gene loss and to assess the strength of phylogenetic association between gene loss and loss of the inverted repeat (IR).• KEY RESULTS: The saguaro plastid genome is the smallest known for an obligately photosynthetic angiosperm (∼113 kb), having lost the IR and plastid ndh genes. This loss supports a statistically strong association across seed plants between the loss of ndh genes and the loss of the IR. Many nonplastid copies of plastid ndh genes were found in the nuclear genome, but none had intact reading frames; nor did three related nuclear-encoded subunits. However, nuclear pgr5, which functions in a partially redundant pathway, was intact.• CONCLUSIONS: The existence of an alternative pathway redundant with the function of the plastid NADH dehydrogenase-like complex (NDH) complex may permit loss of the plastid ndh gene suite in photoautotrophs like saguaro. Loss of these genes may be a recurring mechanism for overall plastid genome size reduction, especially in combination with loss of the IR.

Functional trade-offs in succulent stems predict responses to climate change in columnar cacti.

Columnar cacti occur naturally in many habitats and environments in the Americas but are conspicuously dominant in very dry desert regions. These majestic plants are widely regarded for their cultural, economic, and ecological value and, in many ecosystems, support highly diverse communities of pollinators, seed dispersers, and frugivores. Massive amounts of water and other resources stored in the succulent photosynthetic stems of these species confer a remarkable ability to grow and reproduce during intensely hot and dry periods. Yet many columnar cacti are potentially under severe threat from environmental global changes, including climate change and loss of habitat. Stems in columnar cacti and other cylindrical-stemmed cacti are morphologically diverse; stem volume-to-surface area ratio (V:S) across these taxa varies by almost two orders of magnitude. Intrinsic functional trade-offs are examined here across a broad range of V:S in species of columnar cacti. It is proposed that variation in photosynthetic gas exchange, growth, and response to stress is highly constrained by stem V:S, establishing a mechanistic framework for understanding the sensitivity of columnar cacti to climate change and drought. Specifically, species that develop stems with low V:S, and thus have little storage capacity, are expected to express high mass specific photosynthesis and growth rates under favourable conditions compared with species with high V:S. But the trade-off of having little storage capacity is that low V:S species are likely to be less tolerant of intense or long-duration drought compared with high V:S species. The application of stable isotope measurements of cactus spines as recorders of growth, water relations, and metabolic responses to the environment across species of columnar cacti that vary in V:S is also reviewed. Taken together, our approach provides a coherent theory and required set of observations needed for predicting the responses of columnar cacti to climate change.

Opuntioideae cactus stem Bioimaging analysis: Bridging taxonomy and antimicrobial research.

This study presents a comprehensive scanning electron microscopy (SEM) analysis of Opuntioideae cactus stems indigenous to the arid regions of Saudi Arabia, elucidating their intricate microstructural features. The findings not only advance taxonomic understanding by aiding in species differentiation but also reveal the antimicrobial potential of these cacti, highlighting their significance as valuable natural resources for both ecological and pharmaceutical applications. The present study is aimed to present the stem epidermal anatomical description of Opuntioideae (Cactaceae) belonging to genus Opuntia (five Species), Cylindropuntia (two Species), and Austrocylindropuntia (one Species) as tool for systematic identification. Stem epidermal anatomical features represent here are epidermal cells, stomatal complex, subsidiary cells, and trichomes findings was observed using light microscope and SEM. The stem epidermal sections were made by heating in test tube containing lactic acid and nitric acid protocol. In anatomical findings, irregular, zigzag, wavy, and polygonal epidermal cells with sinuate, sinuous, and straight anticlinal walls were observed. Quantitatively minimum length (28.05 ± 2.05 µm) and width (23.15 ± 3.41 µm) of epidermal cells were noted in Cylindropuntia kleiniae. Paracytic type of stomata present was observed in all species with kidney-shaped guard cell present in six species, and in Opuntia macrocentra and Austrocylindropuntia subulata, dumbbell-shaped guard cells were observed. The largest length of stomata (53.25 ± 2.05 µm) and width of stomata (35.10 ± 5.19 µm) were observed in Opuntia monacantha. In present research work, stem anatomical features show many diverse characters are of special attention for plant taxonomist for the correct identification and provide baseline for further study in subfamily Opuntiodeae. RESEARCH HIGHLIGHTS: The intricate microstructures of Opuntioideae cactus stems. Investigating the antimicrobial potential of compounds found within Opuntioideae cactus stems. Correlations between the unique structural features observed through SEM and the antimicrobial activity of Opuntioideae cactus stem extracts.

Comparative analysis of floral transition and floral organ formation in two contrasting species: Disocactus speciosus and D. eichlamii (Cactaceae).

KEY MESSAGE: Contrasting morphologies in Disocactus are the result of differential development of the vegetative and floral tissue where intercalary growth is involved, resulting in a complex structure, the floral axis. Species from the Cactaceae bear adaptations related with their growth in environments under hydric stress. These adaptations have translated into the reduction and modification of various structures such as leaves, stems, lateral branches, roots and the structuring of flowers in a so-called flower-shoot. While cacti flowers and fruits have a consistent structure with showy hermaphrodite or unisexual flowers that produce a fruit called cactidium, the developmental dynamics of vegetative and reproductive tissues comprising the reproductive unit have only been inferred through the analysis of pre-anthetic buds. Here we present a comparative analysis of two developmental series covering the early stages of flower formation and organ differentiation in Disocactus speciosus and Disocactus eichlamii, which have contrasting floral morphologies. We observe that within the areole, a shoot apical meristem commences to grow upward, producing lateral leaves with a spiral arrangement, rapidly transitioning to a floral meristem. The floral meristem produces tepal primordia and a staminal ring meristem from which numerous or few stamens develop in a centrifugal manner in D. speciosus and D. eichlamii, respectively. Also, the inferior ovary derives from the floral meristem flattening and an upward growth of the surrounding tissue of the underlying stem, producing the pericarpel. This structure is novel to cacti and lacks a clear anatomical delimitation with the carpel wall. Here, we present a first study that documents the early processes taking place during initial meristem determination related to pericarpel development and early floral organ formation in cacti until the establishment of mature floral organs.