Annals of botany最新文献

Background and aims: Many carnivorous plants rely on open fluid pools or droplets to trap and digest arthropod prey. Here, we investigate, for Nepenthes rafflesiana pitcher plants, how they maintain functional fluid pools inside their traps while growing in open sites exposed to changing weather conditions. We hypothesized that very low or high fluid levels reduce the trapping success of the pitcher and that pitchers possess mechanisms to minimize fluctuations of the fluid level.

Methods: Natural fluid levels of N. rafflesiana pitchers were monitored in the field. Effects of the fluid level on prey capture rate and efficiency were quantified with field and laboratory experiments. To test the capacity of plants to respond to changes in fluid level, we experimentally simulated flooding by adding water to pitchers and simulated evaporation by replacing the contents with a smaller volume of concentrated pitcher fluid.

Key results: Freshly opened N. rafflesiana pitchers were approximately half-filled with fluid. Over a 5-week observation period, daily fluctuations of pitcher fluid levels were significantly lower than those of water-filled control vials. Pitchers possess canopy-like lids, but this did not eliminate rainwater influx into pitchers. Both low and very high fluid levels were detrimental to prey capture, with intermediate fluid levels yielding the highest trapping rate. Experimentally flooded pitchers returned to intermediate fluid levels within 2-3 days. Pitchers responded to simulated evaporation by secreting fluid, restoring intermediate fluid levels within 2 days. These homeostatic responses might be triggered by fluid volume or by water potential gradients resulting from changes in concentration.

Conclusions: Nepenthes rafflesiana pitchers regulate their fluid level and remain efficient insect traps in fluctuating weather conditions. This active control is a previously unrecognized pitcher plant adaptation to their exposed habitats; understanding it is important for predicting the ability of these plants to withstand extreme weather conditions enhanced by climate change.

Background: Increasing the number of chromosome sets can increase cell size and improve yields in some crops. Breeding polyploid crops introduces unique challenges compared to diploid species, which has deterred many from exploring the potential benefits. Despite this, recent technological advancements have alleviated some of the challenges related to complex genomes and enabled the improvement of many polyploid crops. Given these advancements, there is a need to review the use of higher ploidy crops and explore potential opportunities for increased chromosome number. Many of the leading bioenergy crops are polyploids and there may be additional opportunities to further diversify feedstocks for emerging bioenergy markets. Such diversification would help to meet the anticipated increase in renewable and sustainable energy demands.

Scope: In this perspective review, we review polyploid crops and the extent to which ploidy level impacts improvement and production. The advantages and disadvantages of each crop are discussed in the context of their ploidy level and end-use. Particular emphasis is given to the current role and potential of polyploidy in creating the next generation of bioenergy feedstocks.

Conclusion: Polyploids present challenges to crop improvement due to their complex genomes, but many of these difficulties can and have been overcome with technological advancements. Approaches that facilitate the use of higher ploidy crops open a path to capturing the many benefits of polyploidy, such as increased fruit and seed size, vigour, diversity, biomass and yield quality. However, these benefits are not observed across all species. This further emphasizes the need to study higher ploidy in traditionally diploid crops.

Background and aims: Since the Industrial Revolution, rising atmospheric CO2, warming and more frequent droughts have significantly impacted ecosystems. While the responses of leaf functional traits to these climate change factors have been widely studied, reproductive traits remain relatively understudied, despite their key role in the diversification and distribution of flowering plants. Here we investigated how elevated CO2, warming, drought and their interactions affect floral, leaf and seed traits in two model grassland species. We also examined how these factors influence trait coordination.

Methods: Two common grassland species, Lotus corniculatus and Crepis capillaris, were sampled from a 10-year climate manipulation experiment. We measured resource economic traits related to organ size, construction cost and dry matter content in both leaves and flowers, along with seed size and number. Univariate and multivariate analyses were used to assess trait responses, and rank-abundance curves were employed to visualize changes in trait coordination across treatments.

Key results: Trait responses to climate change factors varied between species. Drought emerged as the most influential factor, affecting only leaf traits in L. corniculatus, but impacting leaf, floral and seed traits in C. capillaris. Across both species, climate change conditions increased leaf construction costs and reduced flower size. In addition, it led to larger leaves in L. corniculatus and fewer seeds in C. capillaris. Under extreme climate change conditions, trait coordination became stronger in both species, although C. capillaris showed no coordination response specifically to drought.

Conclusions: Our results show that floral economic traits, like leaf traits, are responsive to individual and combined effects of climate change factors. This highlights their importance in shaping plant strategies under environmental stress and emphasizes the need to better integrate floral traits into the whole-plant economic framework.

Background and aims: A low ratio of red to far-red radiation (R:FR ratio) is a signal of competition for light in plant canopies. Plants exposed to low R:FR ratios typically display reduced accumulation of chemical defences against herbivorous insects. In Arabidopsis and other model plants, this effect of low R:FR ratios has been explained on the basis of changes in jasmonate metabolism and signalling. In the genus Solanum, volatile organic compounds, mainly terpenoids produced in trichome glands and released to the environment, are very important signalling molecules involved in plant interactions with insect herbivores. Our aim was to investigate the effect of low R:FR ratios on the terpenes produced and released by plants of the wild tomato species Solanum habrochaites and its consequences for the behaviour of the specialist herbivore Tuta absoluta.

Methods: Plants of S. habrochaites (accession LA2167) were exposed to white light (WL) or WL supplemented with FR and used to evaluate morphological responses, production and emissions of volatile organic compounds, and herbivore attractiveness.

Key results: Solanum habrochaites plants responded to low R:FR ratios with the typical shade avoidance syndrome, characterized by elongated shoots and hyponastic leaves. This morphological response to low R:FR ratios was accompanied by a reduction in the content and emission of 7-epizingiberene, which was correlated with reduced expression of two biosynthetic genes (zFPS and ShZIS) in type VI trichome glands. Finally, choice bioassays demonstrated that T. absoluta moths preferred plants from the FR treatment over control (WL) plants, a result consistent with the reduced production of 7-epizingiberene, which is known for its insect-repellent properties.

Conclusions: Collectively, our results suggest that terpene accumulation in glandular trichomes in S. habrochaites is regulated by light at the transcriptional level and that this regulation could have important consequences for plant resistance to herbivory in plant stands.

Background and aims: Coffee is one of the world's most valuable crops and supports the livelihoods of millions, yet it is increasingly threatened by climate change. Diversifying currently cultivated varieties is crucial for the sector's long-term sustainability. Wild coffee species may carry traits critical for climate resilience but remain largely unexplored. This study provides a first multidisciplinary assessment of Coffea dactylifera, a wild species endemic to the Democratic Republic of Congo (DRC), by comparing its phylogeny, climate niche, morphology and sensory profile with those of the wild relatives of Arabica (C. arabica) and Robusta (C. canephora) coffee.

Methods: We sampled wild C. dactylifera from the DRC and gathered occurrence data. A consensus phylogenetic tree was constructed using ASTRAL-III, based on DArTseq polymorphic genetic markers, and including data from 22 species. Climate niche modelling used filtered occurrence data and bioclimatic variables. Twelve morphological traits were assessed, encompassing leaf morphology, bean characteristics and plant architectural traits. The sensory quality of coffee beans was evaluated using the Fine Robusta Standards and Protocols.

Key results: Coffea dactylifera was identified as a sister species to C. anthonyi, as part of the Coffea eugenioides group. It is adapted to high annual temperatures and low climate seasonality, typical of the lowland forests in Central Africa, where it grows sympatrically with C. canephora. In terms of morphology, it displays a more compact growth form and leaf characteristics that distinguish it from sympatric C. canephora individuals. Sensory evaluation revealed an average score of 78.75 points marked by the 'brown sugar' descriptor, intense sweet aftertaste and syrupy mouthfeel.

Conclusions: C. dactylifera may contribute to climate-resilient coffee breeding. Its genetic proximity to cultivated species, climate niche, compact growth form and promising sensory profile highlight its relevance for conservation and potential use in breeding.

Background and aims: The evolution of intricate floral structures is often a direct consequence of pollinator-mediated selection. In buzz-pollinated plants, pollen is released through vibrations, and control of its removal is crucial for maximizing male reproductive success. The genus Pedicularis presents a compelling case, with many species exhibiting a distinctive upper corolla lip, or galea, shaped like a 'beak' or 'elephant trunk'. The adaptive function of this trait has remained mysterious and largely not subjected to empirical testing. We hypothesized that the beak acts as a dispensing tunnel or poricidal anther, restricting pollen removal by bumblebee pollinators.

Methods: To test this hypothesis, we conducted a comparative field study on three sympatric wild species in the Hengduan Mountains: the beakless Pedicularis densispica, the short-beaked Pedicularis cephalantha and the long-beaked Pedicularis rhinanthoides. All three species share the bumblebee Bombus friseanus as their exclusive pollinator. Our integrative methodology combined detailed observations of pollinator foraging behaviour, direct quantification of pollen removal and deposition per single visit, and controlled laboratory experiments using floral models with pollen analogues to isolate the mechanical effects of beak architecture.

Key results: We found that beakless P. densispica experienced higher visitation frequency but shorter per-flower visit duration. Bumblebees spent a longer time on the two beaked Pedicularis; however, short-beaked species had nearly twice the proportional pollen removal compared with long-beaked species. Furthermore, artificial buzzes on floral models confirmed that longer, curved beaks reduced pollen analogue removal.

Conclusions: Collectively, our findings indicate that the beak structure functions as a pollen-dispensing mechanism, controlling pollen removal in Pedicularis. This first empirical study on the ecological function of the Pedicularis 'elephant trunk' offers crucial insights into floral trait evolution within this diversifying genus, highlighting how specific complicated floral morphologies can tune pollen removal in buzz-pollinated plants.

Background and aims: Acrocomia is a Neotropical palm genus that recently gained attention for its potential as a multipurpose crop. Among its species, A. aculeata and A. totai stand out for their potential in sustainable biofuel production and ecosystem restoration. Despite their relevance, the genomic structure and domestication history of these species remain poorly understood. This study aims to characterize the genetic structure and diversity of A. aculeata and A. totai across their natural distribution, to understand the biogeographical processes behind their differentiation, and to investigate the domestication history of A. aculeata through a genetic, ecological, archaeobotanical and ethnographic lens.

Methods: We used double-digest genotyping-by-sequencing to analyse 85 individuals of A. aculeata and 11 of A. totai from nine countries. Genomic structure was assessed using sparse non-negative matrix factorization, discriminant analysis of principal components and neighbour-joining methods. For A. aculeata, we performed ecological niche modelling during the Pliocene and genome scans to identify outlier single nucleotide polymorphisms (SNPs) within the major genetic groups. These results were integrated with archaeobotanical and ethnographic data to contextualize domestication patterns.

Key results: We identified nine highly structured genetic clusters with low gene flow, confirming two major gene pools: Central and South America, shaped by Pleistocene-Holocene biogeographical dynamics. Using SNPs under selection, we found three regional clusters in A. aculeata: Central America, Amazonia and southeastern Brazil. Functional annotation revealed lineage-specific genes linked to agronomic traits: disease resistance, dwarfism and fruit development in Central America, and lipid metabolism and transcriptional regulation in South America, which may be related to independent domestication pathways over the past 13 000 years.

Conclusions: Our findings offer new insights into the evolutionary and biocultural history of Acrocomia, supporting the existence of distinct evolutionary trajectories. These results highlight the species' potential for sustainable development and emphasize the need for just strategies that include traditional communities in contemporary production systems.

Background and aims: Seed functional traits are poorly understood in species of tropical origin with endospermic or desiccation-sensitive seeds. Species of the genus Coffea have colonized a broad range of forest habitats of Africa and Indian Ocean islands, from seasonally dry savannah woodlands to permanently humid evergreen forests. All Coffea species produce albuminous seeds, most of which are desiccation-sensitive, thereby offering a valuable model to identify adaptive seed traits in this understudied category of plants.

Methods: Several morphological traits (tissue masses and mass ratios, embryo depth inside the endosperm) and physiological traits (desiccation tolerance, germination and seedling establishment kinetics) were measured in 28 Coffea species, and associations with bioclimatic variables and phylogeny were investigated.

Key results: The time required for seed germination was influenced by both the thickness of the micropylar endosperm and the relative mass of the endocarp to the seed. The time from germination to the unfolding of cotyledonary leaves was correlated with the endosperm mass. Finally, the time for seedling establishment, seed germination and drying sensitivity were positively associated with rain variables, suggesting that these physiological traits were driven by adaptation to seasonal water stress. Significant phylogenetic signal was detected for most seed traits with the exception of seed desiccation sensitivity, germination time and embryo depth inside the endosperm, which appeared to be evolutionarily labile, i.e. highly divergent between phylogenetically closely related species that occur in contrasted habitats.

Conclusions: The present study highlights the spectrum of coordinated seed traits shaped by phylogeny and/or ecological adaptation among Coffea species. This is illustrated by the co-option of several characteristics (small, thinly endocarp-coated, desiccation-tolerant and fast-germinating seeds) that enable fast seedling establishment and may confer an ecological advantage in the studied species of the East Africa clade that occur in seasonally dry habitats.

Background and aims: In distylous species, the reciprocal arrangement of sexual organs between long-styled and short-styled individuals promotes disassortative pollen flow through a fine-tuned interaction with pollinators. Despite its evolutionary importance, deviation from this expectation due to suboptimal pollinator performance has been little studied in species with open corollas. This study addresses which insects visiting the flowers of Linum narbonense (Linaceae) promote or break down the expected patterns of pollination.

Methods: Sixteen samplings performed in 12 populations allowed me to analyse the relationship between flower visitors and pollination performance of each floral morph. A total of 3494 stigmas were analysed to measure two components of pollination success: a quantity component that included the proportion of pollinated stigmas and pollen load on stigmas; and a quality component that included for the first time the relationship between pollen tubes and pollen grains on stigmas. Hand-pollination experiments made it possible to characterize the breeding system and to construct a null model of the pollen tube response to legitimate pollen.

Key results: Contrary to long-styled flowers, flowers with short stigmas showed wide variation in the quality of pollen receipt across sampling units, usually being lower than expected by the null model. This variation depended on the proportion of flower visits by insects from the Usia genus (Bombyliidae): low visitation rates by these insects were associated with lower pollen quality deposited on short stigmas.

Conclusions: This study demonstrates the value of addressing the quantity and quality of pollen receipt to correlate pollination success with contemporary pollinator environment. The novel use of the relationship of pollen tube to pollen grain demonstrated the importance of Usia pollinators in promoting disassortative pollination in the distylous L. narbonense. These findings emphasize the importance of identifying which flower visitors promote the functioning of distyly or, conversely, disrupt it, biasing the functional gender of floral morphs.