Annals of botany最新文献

Background and aims: Aridity drives plant adaptations such as reduced stature, sclerophyllous leaves and increased phenolic production. While these patterns are well documented, the role of soil properties in modulating the impact of aridity remains understudied. Trait responses may also vary - converging, diverging, or remaining uncorrelated - across intraspecific and community levels, adding complexity to predictions of ecological responses to arid conditions.

Methods: We investigated how aridity influences six plant functional traits - lateral spread, maximum height, leaf area, specific leaf area (SLA), and the concentrations of total phenolics and flavonoids - at both the species level (focusing on Helichrysum italicum, the dominant species across the surveyed sites) and the community level across 24 dune ecosystems along the Atlantic-Mediterranean coastline of the Iberian Peninsula. We also collected soil samples and used piecewise structural equation modelling to assess whether physico-chemical soil variables - water-holding capacity, nutrient availability, pH and organic matter content - mediate the effects of aridity on plant functional traits.

Key results: We found a significant negative relationship between aridity and both plant height and lateral spread in H. italicum, while leaf area, SLA, total phenolics and flavonoids were not significantly affected. At the community level, aridity was also negatively associated with plant height and lateral spread, positively associated with SLA, and showed no significant relationship with the concentrations of phenolic compounds. Importantly, water-holding capacity was strongly correlated (positively) with aridity; however, the influence of aridity on plant functional traits was not mediated by variation in this factor.

Conclusions: This study demonstrates that aridity consistently influences structural plant traits across species and community levels in Iberian dune ecosystems, with largely convergent responses across organismal scales, and these patterns occur independently of key soil variables such as water-holding capacity.

Background and aims: Many mechanisms respond simultaneously when plants are under drought stress. We examined physiological traits across six Zea mays genotypes varying in grain productivity under water limitation to identify plant strategies associated with greater productivity under limited water.

Methods: Data were collected on diurnal stomatal conductance (gs), maximum shoot hydraulic conductivity, pressurized root flow, light-adapted chlorophyll fluorescence and gas exchange on well-watered and water-limited plants in the field and greenhouse to identify traits and general strategies associated with grain production under water limitations in the field.

Key results: Results indicated that greater grain production was associated with greater peak gs among genotypes and treatments, and, when grown under limited water, maximum whole shoot hydraulic conductivity and pressurized root flow, the last of which may be linked to refilling of capacitance tissues to support plant gas exchange under limited water availability. Additionally, genotypes with greater grain production under limited water availability had reduced effective quantum yield of chlorophyll fluorescence relative to lower-yielding genotypes, suggesting trade-offs limiting maximum electron transport for the safety of photosynthetic apparatuses aligned with a productive strategy under limited water availability. Because both photosynthesis and gs declined similarly among genotypes grown with limited water, instantaneous water use efficiency determined under limited water in the greenhouse was similar among genotypes and did not show any relationship with grain production under limited water availability in the field.

Conclusions: A successful strategy for maize under cyclic water limitation appears to be to maintain growth with greater stomatal conductance and hydraulic conductivity, while protecting photosynthetic apparatuses. Finding a strong linkage between grain productivity and pressurized root flow, with its potential connection to capacitance tissues, emphasizes the need to explore hydraulic mechanisms that have received little attention to date but could provide a crucial mechanism for maintaining productivity when water availability is limited.

Backgrounds and aims: In palms, many dioecious species have emerged from at least eight independent events; the mechanisms of sex determination remain poorly understood. Here, we identify and compare the sex chromosomes of Kerriodoxa elegans with those of the well-studied date palm (Phoenix dactylifera), which evolved dioecy independently from a monoclinous common ancestor.

Methods: We developed target sequence capture kits and inferred sex-linked genes using a probabilistic approach in both species.

Key results: We find a striking similarity between the sex-linked regions of K. elegans and P. dactylifera, with the majority of sex-linked genes being common between the two species. However, we confirm that these regions evolved independently, much later than the split between the lineages.

Conclusions: This case of convergent evolution seems to be unique in plants so far, and raises questions on the mechanisms of sex determination. This could be explained by the presence of genes related to floral sex development and sex determination in this region, which have been recruited during the evolution of sex chromosomes, even though the genes involved may differ between the two species.

Background and aims: Viola tricolor subsp. macedonica and Viola arsenica are metallophytes from the abandoned Allchar mine site in the Republic of North Macedonia, an area extremely enriched in thallium and arsenic, with up to 5750 and 12 800 mg kg-1 in the soil, respectively. This study aimed to infer tolerance mechanisms evolved in the two Viola species by analysis of the tissue-level distribution of arsenic and thallium.

Methods: Seedlings of V. tricolor subsp. macedonica and V. arsenica were grown under different thallium and arsenic treatments in hydroponics. Synchrotron-based micro-X-ray fluorescence (µXRF) analysis was used to elucidate elemental distribution in hydrated plant organs and tissues.

Key results: Plants dosed with increasing concentrations of arsenic and thallium had higher accumulation of these elements, especially in the roots. In V. arsenica, thallium mainly accumulated in the shoots, with the mature leaves being the main site of deposition. In the leaves of V. tricolor subsp. macedonica, the highest thallium concentrations occured around the stomata.

Conclusions: Foliar accumulation of thallium is the main tolerance strategy in V. arsenica, whereas the limited translocation into the shoot and potentially excreting excess thallium through the stomata in V. tricolor subsp. macedonica appears to be an important mechanism for survival in the extremely toxic habitat at the Allchar site.

Background and aims: Pollen:ovule ratios are often lower in species and populations with higher selfing rates. This may be due either to higher pollination efficiency through selfing, or to lower male competition when less allo-pollen is available. Changes in pollination can also impact pollen traits, such as the number of apertures. Viola arvensis has experienced a rapid recent increase in selfing rates, and a rapid floral trait evolution towards the selfing syndrome. This study tests the hypothesis that V. arvensis is also undergoing a rapid evolution in its pollen:ovule ratio and pollen heteromorphism.

Methods: Using the resurrection ecology methodology, we compared four ancestral populations (from ca. 30 years ago) to their descendants (from 2021). We counted ovules and pollen and measured the different pollen aperture morphs in 50 individuals per population. We also developed a model to better understand the links between the number of apertures and the mating system.

Key results: We found no temporal change in pollen or ovule production. However, populations with the lowest pollen:ovule ratios were also those with the highest ancestral selfing rates, suggesting that the pollen:ovule ratio could have evolved on a similar timescale to population differentiation. Our model predicts a positive correlation between number of apertures and selfing rates, if pollination parameters remain constant. However, this positive correlation was not found in our results, neither across populations nor through time.

Conclusions: Unlike floral morphology, pollen and ovule production did not evolve rapidly with increased selfing rates, suggesting a delayed change of the pollen:ovule ratio compared to other traits of the selfing syndrome. The absence of correlation between pollen heteromorphism and selfing rate can be explained by multiple (non-mutually exclusive) factors: a decrease in allo-pollen deposition correlated with the evolution of the selfing syndrome, pollinator declines or the absence of selection in this trait.

Background: Measuring costs of male versus female reproduction in cosexual species is challenging because the currency and timing of allocation can differ between the two sexual functions. In contrast, costs of male versus female reproduction can be measured indirectly in dioecious species in terms of sex-specific life-history trade-offs with growth and survival. Yet despite abundant evidence for differences in life history between males and females, there remains confusion over how such differences should be interpreted.

Scope: Here, I address misconceptions in interpreting potential differences in the costs of reproduction between the sexes, drawing attention to the relevance of: (1) theories of sex-allocation versus life-history evolution; and (2) observations of sex-ratio variation.

Key results: Sex-allocation theory predicts a mother's investment in sons versus daughters and is thus relevant to primary sex ratios at the seed stage. Life-history theory is relevant to trade-offs between, for example, reproduction and survival, and is thus relevant to secondary sex ratios of adults affected by sex-biased mortality. The preponderance of species with male- in comparison to female-biased secondary sex ratios points to a frequently greater cost of reproduction for females.

Conclusions: Male and female costs of reproduction often differ, but there remain unanswered questions about why one sex (most often the female function) should often be more expensive than the other. A correct understanding of theoretical predictions will help future research to address such questions.

Background and aims: The vegetative body of Pilostyles (Apodanthaceae) is highly reduced, composed of cell clusters that occupy the bark of the host plant. From these clusters, tracheary elements connect with the host vascular system during the parasite reproductive stages. We analyse the developmental morphology of Pilostyles blanchetii to gain a better understanding of its growth within the host body, in addition to xylem and phloem connections between the two plants, providing new interpretations about the life history of the parasite.

Methods: Iodine and lead contrast solutions were perfused through samples of parasitized host material before microtomography scanning to facilitate posterior virtual segmentation of parasite structures within host tissues. Samples were then prepared for light, fluorescence and confocal microscopy to analyse xylem and phloem connections between parasite and host plants.

Key results: We detected the presence of parasitic tissue within the host body before flower meristem differentiation and revealed the interconnectedness of the parasitic endophyte. Parasite-host xylem connections are mediated by highly modified vessel elements differentiated in the parasite sinkers. Within the host bark, the parasite develops small sieve tube elements lacking companion cells.

Conclusions: Pilostyles blanchetii develops an extensive tissue network within the bark of its hosts, linking pistillate and staminate flowers, thus suggesting monoecy. Vascular tissue is extremely reduced and includes only vessel elements for the xylem and sieve tube elements for the phloem, which connect directly to the corresponding cells of the host.

Background: Traditionally defined as plant blindness, plant awareness disparity or plant imperception, a general low interest in plants partially stems from poor teacher training in botany, traditional lecture-style classes and a lack of attractive methods. Major changes in didactical-methodological strategies are needed to break the cycle of plant imperception caused by inadequate teaching practices, as it directly affects research on plants and plant conservation. Low plant awareness also directly impacts society, such as a low perception of plant-based foods and not linking plants to climate change, biodiversity loss, environmental services, desertification, deforestation, poor soil and poor water quality.

Scope: Here we share a method based on how teachers can use audio-visual and artistic materials as advance organizers to effectively engage students in botany courses in high schools and undergraduate courses.

Conclusions: The use of audio-visual material with botanical visual clues as advance organizers, or a cognitive bridge between previous knowledge and new knowledge, led to meaningful learning in botany. Our results show that this method is positive for the teacher-student relationship and that pop culture/artistic references can establish emotional connection between students and plants. Increased motivation and participation resulted in improved engagement of students with botany, observed as more frequent unprompted use of botanical terms, fewer complaints about theoretical botany, better academic performance and improved teamwork.

Background and aims: In perennial crops, efficient resource acquisition critically depends on whole-plant architecture, encompassing both canopy and root systems. In grafted grapevine, research has largely focused on scion canopy structure, whereas root system architecture - despite its key role in water and nutrient uptake - remains underexplored. This study comprehensively analysed whole-plant 3-D architecture during vineyard establishment, investigating how different rootstock genotypes influence both root and shoot development.

Methods: Riesling scions were grafted onto three rootstock genotypes (101-14, SO4 and 110R) and planted in a vineyard following a randomized complete block design. Whole-plant excavations and high-resolution 3-D digitization were performed to capture spatial data of root and shoot systems from 96 vines at four time points over 2 years (3, 6, 15 and 18 months after planting). Key architectural parameters and biomass partitioning were quantified.

Key results: Rootstock genotype strongly influenced whole-plant 3-D architecture and biomass allocation. 110R developed significantly deeper, vertically oriented root systems (max depth 180 cm) and exhibited higher root-to-shoot biomass ratios compared to SO4 and 101-14. Multivariate analysis identified deep root length and overall spatial root system dimensions as primary discriminators among genotypes. Root growth across all genotypes was spatially biased along the planting row, with limited extension into the inter-row soil.

Conclusions: Rootstock genotype is a key determinant of whole-plant 3-D architecture and biomass partitioning. The integration of above- and below-ground structural data enables mechanistic interpretation of rootstock-mediated traits relevant to resource acquisition and stress adaptation. Our comprehensive 3-D data set provides a valuable foundation for functional-structural plant modelling and offers practical insights for targeted breeding and management strategies to enhance climate resilience in perennial crops.