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Araucaria angustifolia (Bertol.) Kuntze, commonly known as Brazilian pine, is a significant tree species in the Brazilian flora that once covered an area of 200,000 km[sup.2] in the Southern region. During the 1970s, high-quality timber logs from this conifer became the primary export product of the country. However, the species is endangered due to uncontrolled exploitation and is subject to a harvesting ban. It is crucial, therefore, to explore sustainable cultivation methods for this species, which necessitates urgent research and scientific insights. In this study, we present a simulation of a management strategy for in situ conservation by manipulating growth space and crown size dynamics. Forest inventory data and mixed forest regression equations were employed to describe the horizontal dimensions of average and maximum potential crown growth, resulting in two management scenarios. The results presented in management diagrams show that both approaches required logging numerous trees to ensure adequate space for healthy tree growth and provide soil coverage and forest protection. Therefore, the absence of effective forest management initiatives for Araucaria forests may have further implications for the structure, production, conservation, and overall development. To address these challenges, we propose two hypotheses: firstly, that tree diameter depends on crown dimensions, which are in turn influenced by tree growth space, and, secondly, that crown dimensions serve as a reliable indicator of existing competition and can be utilized to simulate forest management practices. We urge that implementing sustainable forest management initiatives for Araucaria angustifolia at selected locations can contribute to expanding natural forest areas, mitigate deterioration caused by high competition, discourage illegal logging, and prevent overexploitation of their edible seeds, which hinders regeneration. Our results underscore the significant implications of the lack of forest management initiatives in rural properties, potentially resulting in irreversible deterioration. The exact consequences of this deterioration remain unclear, emphasizing the need for further studies to understand its eventual effects on the growth reaction of trees of different diameters, ages, and crown conditions after the liberation of their crowns.

Notes how the root rot causing oomycete, Phytophthora agathidicida, threatens the long-term survival of the iconic New Zealand kauri tree. Describes a loop-mediated isothermal amplification (LAMP) assay for the detection of P. agathidicida that targets a portion of the mitochondrial apocytochrome b coding sequence. Discusses the various ways such an assay can be used in the communities affected. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.

The ability of lineages to disperse long distances over evolutionary timescales may be influenced by the gain or loss of traits adapted to enhance local, ecological dispersal. For example, some species in the southern conifer family Podocarpaceae have fleshy cones that encourage bird dispersal, but it is unknown how this trait has influenced the clade’s historical biogeography, or its importance compared with other predictors of dispersal such as the geographic distance between regions. We answer these questions quantitatively by using a dated phylogeny of 197 species of southern conifers (Podocarpaceae and their sister family Araucariaceae) to statistically compare standard, trait-independent biogeography models with new BioGeoBEARS models where an evolving trait can influence dispersal probability, and trait history, biogeographical history, and model parameters are jointly inferred. We validate the method with simulation-inference experiments. Comparing all models, those that include trait-dependent dispersal accrue 87.5% of the corrected Akaike Information Criterion (AICc) model weight. Averaged across all models, lineages with nonfleshy cones had a dispersal probability multiplier of 0.49 compared with lineages with fleshy cones. Distance is included as a predictor of dispersal in all credible models (100% model weight). However, models with changing geography earned only 22.0% of the model weight, and models submerging New Caledonia/New Zealand earned only 0.01%. The importance of traits and distance suggests that long-distance dispersal over macroevolutionary timespans should not be thought of as a highly unpredictable chance event. Instead, long-distance dispersal can be modeled, allowing statistical model comparison to quantify support for different hypotheses.

Premise of the Study Conifers are an important living seed plant lineage with an extensive fossil record spanning more than 300 million years. The group therefore provides an excellent opportunity to explore congruence and conflict between dated molecular phylogenies and the fossil record. Methods We surveyed the current state of knowledge in conifer phylogenetics to present a new time‐calibrated molecular tree that samples ~90% of extant species diversity. We compared phylogenetic relationships and estimated divergence ages in this new phylogeny with the paleobotanical record, focusing on clades that are species‐rich and well known from fossils. Key Results Molecular topologies and estimated divergence ages largely agree with the fossil record in Cupressaceae, conflict with it in Araucariaceae, and are ambiguous in Pinaceae and Podocarpaceae. Molecular phylogenies provide insights into some fundamental questions in conifer evolution, such as the origin of their seed cones, but using them to reconstruct the evolutionary history of specific traits can be challenging. Conclusions Molecular phylogenies are useful for answering deep questions in conifer evolution if they depend on understanding relationships among extant lineages. Because of extinction, however, molecular datasets poorly sample diversity from periods much earlier than the Late Cretaceous. This fundamentally limits their utility for understanding deep patterns of character evolution and resolving the overall pattern of conifer phylogeny.

Significance A major determinant of plant species distribution on Earth is a specific tolerance to soil drying, yet there are currently no functional or anatomical characteristics that can predict species’ requirement for rainfall. This study examines the systems responsible for controlling water delivery and water loss in the leaves of conifers and finds functional evidence of how conifers have evolved in drying climates over the course of the last 150 million years. Two “strategies” for conserving water during water stress emerged. One group relied on the plant hormone abscisic acid to maintain stomata closed during sustained drought, and another, more derived group allowed leaves to dehydrate and resisted damage by producing a water transport system capable of functioning under the extreme tension that develops in water-stressed plants. Water stress is one of the primary selective forces in plant evolution. There are characters often cited as adaptations to water stress, but links between the function of these traits and adaptation to drying climates are tenuous. Here we combine distributional, climatic, and physiological evidence from 42 species of conifers to show that the evolution of drought resistance follows two distinct pathways, both involving the coordinated evolution of tissues regulating water supply (xylem) and water loss (stomatal pores) in leaves. Only species with very efficient stomatal closure, and hence low minimum rates of water loss, inhabit dry habitats, but species diverged in their apparent mechanism for maintaining closed stomata during drought. An ancestral mechanism found in Pinaceae and Araucariaceae species relies on high levels of the hormone abscisic acid (ABA) to close stomata during water stress. A second mechanism, found in the majority of Cupressaceae species, uses leaf desiccation rather than high ABA levels to close stomata during sustained water stress. Species in the latter group were characterized by xylem tissues with extreme resistance to embolism but low levels of foliar ABA after 30 d without water. The combination of low levels of ABA under stress with cavitation-resistant xylem enables these species to prolong stomatal opening during drought, potentially extending their photosynthetic activity between rainfall events. Our data demonstrate a surprising simplicity in the way conifers evolved to cope with water shortage, indicating a critical interaction between xylem and stomatal tissues during the process of evolution to dry climates.

Araucaria araucana is an important seed and timber-yielding tree that grows naturally in the tropical and subtropical regions of the Andes in Argentina and Chile, and has also been introduced as an ornamental species in Europe. Genetic diversity has been observed in A. araucana native populations, but there have been no prior studies on the genetic diversity estimates of this species introduced in Europe. On the other hand, assessment of the genetic variation in Araucaria populations occurring in Europe might be an important tool in the selection of appropriate germplasms for ornamental nursery production and breeding strategies. In this study, morphological and genetic diversity was analysed using a previously defined descriptor list and SSR molecular markers in four putative populations of A. araucana, individuated in the Pistoia Nursery District (Tuscany, Italy). In total, 26 morphological descriptors and 28 SSR primer pairs were used for a diversity assessment of specimens. Results provide evidence for genetic and morphological correspondence among the four putative Araucaria populations. PCA and cluster analyses based on morphological traits clearly revealed three distinct clusters of specimens. SSR primers yielded 68% polymorphic loci among the considered populations, and 18 of them displayed informativeness for population genetics, according to a Polymorphic Information Content value larger than 0.25. This marker set revealed significant genetic differentiation, and UPGMA analysis enabled separation of these populations on the basis of their genetic distances into three main groups, which largely overlapped with clusters in the dendrogram obtained from the morphological data. In particular, in both cluster diagrams, all accessions belonging to a specific population were well separated from all the others due to matrix distances and differences in the canopy density that are more similar to conifers such as spruce, pine, or fir. ANOVA analysis and the F[sub.ST] value indicated a large between-population genetic variation. The Mantel test suggested that genetic differentiation between the four studied populations was positively correlated with morphological distance (r = 0.141, p < 0.05). Thus, both morphological and genetic markers showed applicability across populations of different seed origins and proved suitable for the identification and characterization of A. araucana accessions.

Somatic embryogenesis has been shown to be an efficient tool for studying processes based on cell growth and development. The fine regulation of the cell cycle is essential for proper embryo formation during the process of somatic embryogenesis. The aims of the present work were to identify and perform a structural and functional characterization of Mps1 and to analyze the effects of the inhibition of this protein on cellular growth and pro-embryogenic mass (PEM) morphology in embryogenic cultures of A. angustifolia. A single-copy Mps1 gene named AaMps1 was retrieved from the A. angustifolia transcriptome database, and through a mass spectrometry approach, AaMps1 was identified and quantified in embryogenic cultures. The Mps1 inhibitor SP600125 (10 [mu]M) inhibited cellular growth and changed PEMs, and these effects were accompanied by a reduction in AaMps1 protein levels in embryogenic cultures. Our work has identified the Mps1 protein in a gymnosperm species for the first time, and we have shown that inhibiting Mps1 affects cellular growth and PEM differentiation during A. angustifolia somatic embryogenesis. These data will be useful for better understanding cell cycle control during somatic embryogenesis in plants.

New Zealand kauri is an ancient, iconic, gymnosperm tree species that is under threat from a lethal dieback disease caused by the oomycete Phytophthora agathidicida. To gain insight into this pathogen, we determined whether proteinaceous effectors of P. agathidicida interact with the immune system of a model angiosperm, Nicotiana, as previously shown for Phytophthora pathogens of angiosperms. From the P. agathidicida genome, we defined and analysed a set of RXLR effectors, a class of proteins that typically have important roles in suppressing or activating the plant immune system. RXLRs were screened for their ability to activate or suppress the Nicotiana plant immune system using Agrobacterium tumefaciens transient transformation assays. Nine P. agathidicida RXLRs triggered cell death or suppressed plant immunity in Nicotiana, of which three were expressed in kauri. For the most highly expressed, P. agathidicida (Pa) RXLR24, candidate cognate immune receptors associated with cell death were identified in Nicotiana benthamiana using RNA silencing‐based approaches. Our results show that RXLRs of a pathogen of gymnosperms can interact with the immune system of an angiosperm species. This study provides an important foundation for studying the molecular basis of plant–pathogen interactions in gymnosperm forest trees, including kauri. RXLR effectors of the kauri dieback pathogen Phytophthora agathidicida triggered or suppressed immunity in Nicotiana, showing that RXLRs from a gymnosperm pathogen can interact with an angiosperm immune system.

Phylogenetic reconstruction is fundamental to study evolutionary biology and historical biogeography. However, there was not a molecular phylogeny of gymnosperms represented by extensive sampling at the genus level, and most published phylogenies of this group were constructed based on cytoplasmic DNA markers and/or the multi-copy nuclear ribosomal DNA. In this study, we use LFY and NLY, two single-copy nuclear genes that originated from an ancient gene duplication in the ancestor of seed plants, to reconstruct the phylogeny and estimate divergence times of gymnosperms based on a complete sampling of extant genera. The results indicate that the combined LFY and NLY coding sequences can resolve interfamilial relationships of gymnosperms and intergeneric relationships of most families. Moreover, the addition of intron sequences can improve the resolution in Podocarpaceae but not in cycads, although divergence times of the cycad genera are similar to or longer than those of the Podocarpaceae genera. Our study strongly supports cycads as the basal-most lineage of gymnosperms rather than sister to Ginkgoaceae, and a sister relationship between Podocarpaceae and Araucariaceae and between Cephalotaxaceae-Taxaceae and Cupressaceae. In addition, intergeneric relationships of some families that were controversial, and the relationships between Taxaceae and Cephalotaxaceae and between conifers and Gnetales are discussed based on the nuclear gene evidence. The molecular dating analysis suggests that drastic extinctions occurred in the early evolution of gymnosperms, and extant coniferous genera in the Northern Hemisphere are older than those in the Southern Hemisphere on average. This study provides an evolutionary framework for future studies on gymnosperms.