Annals of botany最新文献

Background and aims: Annuals produce little wood due to their short life cycle, while perennials can accumulate more, though not all do. Consequently, lifespan extension is a prerequisite for-but not synonymous with-secondary woodiness. Even if a shift to perenniality does not substantially increase wood production, it may still affect wood anatomy, as annuals prioritise rapid growth, whereas perennials invest in structural resilience. Heliophila, a genus of the Brassicaceae from the Cape Floristic Region, provides an excellent system to investigate drivers of secondary woodiness and the impact of lifespan shifts on wood traits due to its multiple independent lifespan transitions and occurrence of secondary woodiness.

Methods: We reconstructed evolutionary transitions between annual and perennial lifespans and between herbaceous and secondarily woody habits. Using phylogenetically informed statistics, we analysed the relationship between climate, lifespan, and nine wood anatomical traits. Lifespan-specific evolutionary optima for these traits were estimated and compared. We also tested whether secondary woodiness in Heliophila is associated with specific climatic niches.

Key results: Lifespan shifts in Heliophila are primarily driven by water availability and seasonality, with perennials evolving in wetter and less seasonal environments. Secondary woodiness may be more frequent in warmer niches, though this trend was not statistically supported, likely due to the limited number of secondarily woody species. Lifespan, not climate, better predicted wood traits: annuals had longer, thinner-walled cells, while perennials had shorter cells with thicker walls.

Conclusions: In Heliophila, a shift in climatic niche prompts a change in lifespan, followed by slower adaptations in wood anatomy. Possibly, this pattern arises because alterations in lifespan affect stem architecture, establishing a developmental framework that governs subsequent anatomical adjustments. Furthermore, although not statistically robust, increased wood production may be linked to warmer niches, potentially associated with a temperature-driven enhancement in lignin biosynthesis that reinforces stem structure.

Background: Biodiversity is the variability among living organisms that exists within species, between species and of ecosystems. Yet, genetic diversity, the within species component of biodiversity, is rarely considered as a conservation concern or goal in protected areas.

Scope: In this perspective, we explore possible reasons why genetic diversity is poorly considered in conservation and ecological restoration. We also present the case study of a threatened forest conifer in France (Pinus nigra ssp. salzmannii (Dunal) Franco, Salzmann's pine) that we offer as proof of how straightforward implementation of genetic diversity conservation goals can be in protected areas.

Conclusions: Scientific studies in the fields of either conservation or biodiversity consider genetics in less than 10% of scientific productions. While genetic tools are used for taxonomic delineation, concerns about diversity within species at population level appear comparatively rare in conservation and biodiversity science or management. The use of genetic tools for the conservation of genetic diversity of Salzmann's pine in France clarified its taxonomic status, identified populations relevant for in-situ conservation compatible with habitat conservation and made it possible to select genetically original individual trees that could be grafted as a core collection for dynamic ex-situ conservation. As threats on biodiversity increase worldwide, fully integrating genetic diversity in conservation demands that conservation adopts an evolutionary centered, nature for itself perspective, rather than either an anthropocentric, resource focused perspective or a bio-centered, emblematic species focused perspective.

Background and aims: Shattering is a natural phenomenon displayed by dry fruits or capsules that dehisce at maturity to distribute seeds. This undesirable trait in commercially-important Plantago ovata can cause high yield losses, especially when triggered by weather events. However, the underlying internal and external triggers of capsule dehiscence are not well understood. This study aimed to characterise the morphological features of Plantago seed capsules, focusing on dehiscence zones (DZ) and structural components influencing capsule opening.

Methods: Capsule development and dehiscence in P. ovata were examined using staining, immunolabelling, and electron microscopy, with particular emphasis on the dehiscence zone between the lid and base. Polysaccharide-directed antibodies and monosaccharide profiling were used to analyse cell wall composition. Findings were compared across three Plantago relatives ranked by manually-induced dehiscence propensity.

Key results: Capsule walls are dominated by xylans and differentially-esterified pectins. The operculum (lid) shows a distinct lignification pattern absent in the capsule base. A key feature is the "operculum hook", a vertical cell layer with thickened walls enriched in xylans and lignin, connecting the lid to the base. The DZ contains two separation layers: the first formed by cuboidal cells lacking unesterified homogalacturonan with the second layer found at the junction between the operculum hook and the capsule base. Dehiscence occurs in two steps, involving abscission at these zones. Structural differences in the operculum hook, particularly cell wall thickness, vary across Plantago species and are correlated with ordinally ranked differences in manually-triggered dehiscence.

Conclusions: Capsule dehiscence in Plantago involves two sequential separation events influenced by cell wall composition and structure. Cell wall dimensions at the operculum hook base could be critical in determining dehiscence ease. These findings provide new insights into capsule development and dehiscence, which could inform future breeding strategies to reduce yield losses in P. ovata and other crops.

Background and aims: Salicornia europaea L., a succulent euhalophyte plant, has been found to exhibit optimal reproductive capabilities under appropriate salinity concentrations. However, the underlying metabolic changes are not yet fully understood.

Methods: In this study, we conducted a comprehensive analysis combining transcriptomic and lipidomic techniques to investigate the molecular mechanisms of lipid metabolism in response to different NaCl concentrations (0 and 200 mM).

Results: Transcriptomic data demonstrated that salt treatment mainly affected processes including lipid biosynthesis, phosphatidylinositol signalling and glycerophospholipid metabolism. The expression levels of several key genes involved in salt tolerance, namely SeSOS1, SeNHX1, SeVHA-A, SeVP1 and SePSS, were found to be upregulated upon NaCl treatment. A total of 485 lipid compounds were identified, of which 27 changed in abundance during salt treatment, including the enrichment of phospholipids and sphingolipids. Moreover, the increase in the double-bond index was mainly attributable to phospholipids and sphingolipids. Comparing the acyl chain length showed that the acyl chain length coefficient of sphingosine-1-phosphate decreased significantly in the presence of 200 mM NaCl.

Conclusions: This study suggests that S. europaea adapts to saline environments by altering phospholipids and sphingolipids to improve salt tolerance. The salinity response of S. europaea can provide important insights into the action of lipids and their salt adaptation mechanisms.

Background and aims: A hierarchical micro-topography of ridges and steps renders the trap rim of carnivorous Nepenthes pitcher plants unusually wettable, and slippery for insects when wet. This complex three-dimensional epidermis structure forms, hidden from plain sight, inside the still-closed developing pitcher bud. Here, we reveal the sequence of epidermal patterning events that shape the trap rim. By linking this sequence to externally visible markers of bud development, we provide a framework for targeting individual stages of surface development in future studies.

Methods: We used cryo-scanning electron microscopy to investigate the detailed morphogenesis and epidermal patterning of the Nepenthes × hookeriana pitcher rim. In addition, we collected morphometric and qualitative data from developing pitcher traps including those sampled for microscopy.

Key results: We identified three consecutive patterning events. First, strictly oriented cell divisions resulted in radially aligned rows of cells and established a macroscopic ridge-and-groove pattern. Next, conical papillate cells formed, and papillae elongated towards the trap interior, increasingly overlapping adjacent cells and eventually forming continuous microscopic ridges. In between these ridges, the flattened papillae formed acutely angled arched steps. Finally, the cells elongated radially, thereby establishing the convex collar shape of the rim. This general sequence of surface development also showed a spatial progression from the outer to the inner trap rim edge, with several consecutive developmental stages co-occurring at any given time.

Conclusions: We demonstrate that the complex surface micro-topography of the Nepenthes pitcher rim develops by sequentially combining widespread, evolutionarily conserved epidermal patterning processes in a new way. This makes the Nepenthes trap rim an excellent model for studying epidermal patterning mechanisms in leaves.

Background and aims: Bamboo is a grass in the Poaceae family with various applications. Bamboo leaves can accumulate high silica. However, silica deposition in bamboo has received limited study. Therefore, this research investigated silica accumulation in Dendrocalamus copelandii leaves. The study includes the localization of silica through phytolith morphology, examination of the distribution patterns of phytoliths in epidermal tissues, analysis of silica accumulation within specialized silica cells (short cells) and analysis of silicon concentration across various leaf developmental stages.

Methods: We used imaging techniques, including differential interference contrast and a scanning electron microscope incorporating an energy-dispersive X-ray spectrometer, to investigate silica accumulation in bamboo leaves. We also analysed the silicon concentration using inductively coupled plasma-optical emission spectroscopy.

Key results: Leaves of D. copelandii exhibited 11 phytolith morphotypes, namely Bilobate, Polylobate, Saddle, Acute, Acute bulbosus, Microhair, Stomata, Bulliform flabellate, Elongate sinuate, Elongate entire and Tracheary. Most of these phytoliths were found in short cells (Bilobate, Polylobate and Saddle) of epidermal tissues. The short cells were arranged transversely along the leaf length. Bilobate phytoliths were found in both the abaxial and adaxial epidermis, whereas the Saddle morphotype was found only in the abaxial epidermis. Silica accumulation in the short cells of unexpanded leaves begins at the leaf apex, spreads to the middle and base positions, and accumulates initially in the abaxial epidermis, then the adaxial epidermis. Moreover, bamboo leaves accumulate a higher silicon concentration as they age.

Conclusions: Phytolith morphotypes and silica accumulation in epidermal short cells are key factors in understanding silica deposition. Leaf age and climate significantly impact the silicon concentration in bamboo leaves. Our findings are informative for archaeological studies and for plant taxonomical classification. The results are also applicable for biotechnological applications.

The key to the wide geographical distribution of wheat is its high adaptability. One of the most commonly used methods for studying adaptation is investigation of the transition between the vegetative-generative phase and the subsequent intensive stem elongation process. These processes are determined largely by changes in ambient temperature, the diurnal and annual periodicity of daylength, and the composition of the light spectrum. Many genes are involved in the perception of external environmental signals, forming a complex network of interconnections that are then integrated by a few integrator genes. This hierarchical cascade system ensures the precise occurrence of the developmental stages that enable maximum productivity. This review presents the interrelationship of molecular-genetic pathways (Earliness per se, circadian/photoperiod length, vernalization - cold requirement, phytohormonal - gibberellic acid, light perception, ambient temperature perception and ageing - miRNA) responsible for environmental adaptation in wheat. Detailed molecular genetic mapping of wheat adaptability will allow breeders to incorporate new alleles that will create varieties best adapted to local environmental conditions.

Background and aims: Ecological speciation is frequently invoked as a driver of plant radiation, but the behaviour of environmental niches during radiation is contentious, with patterns ranging from niche conservatism to niche divergence. Here, we investigated climatic and edaphic niche shifts during radiation in a western Mediterranean lineage of the genus Linaria (Plantaginaceae).

Methods: Detailed distributional, phylogenomic and environmental data were integrated to analyse changes in climatic and edaphic niches in a spatiotemporal context, including calculation of niche overlap, niche equivalency and similarity tests, maximum entropy modelling, phylogenetic comparative methods and biogeographical analyses.

Key results: Active divergence of climatic and edaphic niches within a limited subset of available conditions was detected among the eight study species and particularly between sister species. Speciation and niche divergence are estimated to have happened in the southern Iberian Peninsula in Mediterranean conditions, followed by waxing and waning of distribution ranges resulting from the Quaternary climatic cycles.

Conclusions: The results support the idea that the prevalence of niche conservatism or niche divergence patterns is a matter of phylogenetic scale. Habitat isolation pertaining to both climatic and soil conditions appears to have played a role in plant speciation in the western Mediterranean biodiversity hotspot, most probably in combination with pollinator isolation and some degree of geographical isolation. These findings are in agreement with an adaptive radiation scenario incorporating certain non-adaptive features.