Male Cones Research Articles

Classostrobus doylei, a new cheirolepidiaceous cone with in situ pollen from the Figueira da Foz Formation (lower Aptian – upper Albian), western Portugal

The genus Classostrobus was established to accommodate unattached Classopollis-containing cones. It is noteworthy that Classopollis as a whole shows significant variation in morphological structure, and male cones bearing Classopollis pollen grains are rarer than vegetative organs of cheirolepidiaceous conifers. A new cheirolepidiaceous microsporangiate cone, Classostrobus doylei, containing Classopollis triangulus pollen grains is described for the first time based on a single specimen from sedimentary rocks exposed in the Carregueira open-cast clay pit complex close to the small village of Juncal, in the Estremadura region, (Lusitanian Basin, western Portugal). The plant-bearing horizon from Carregueira is included in the basal part of the Famalicão Member of the Figueira da Foz Formation, considered to be of late Aptian – early Albian age. The new microsporangiate cone is small, about 2.0 mm long and 1.5 mm wide, ovoid in shape and of typically coniferous structure, probably belonging to Pseudofrenelopsis zlatkoi. The male cone consists of about 16 peltate, imbricated microsporophylls of deltoid shape. Each sporophyll is composed of a stalk and deltoid head showing abaxially 4-5 ovoid pollen sacs. The marginal parts of the sporophylls display long and unicellular trichomes. The observed in situ pollen grains are triangular to subcircular in outline, 16-28 μm in diameter, with an equatorial girdle, subequatorial rimula, proximal trilete scar and a distal cryptopore. The pollen ultrastructure is typical for Classopollis, except for the destroyed condition of the exine. The in situ pollen grains under study are consistent with the data on known dispersed Classopollis triangulus.

Fossil conifers from the Middle Jurassic of the Northern Caucasus, Russia: female and male cones, leafy shoots and anatomically preserved wood

Fossil conifers from the Middle Jurassic of the Northern Caucasus, Russia: female and male cones, leafy shoots and anatomically preserved wood

Correction: Evaluation of thermoregulation of different pine organs in early spring and estimation of heat reward for the western conifer seed bug (Leptoglossus occidentalis) on male cones

Correction: Evaluation of thermoregulation of different pine organs in early spring and estimation of heat reward for the western conifer seed bug (Leptoglossus occidentalis) on male cones

Adaptive Morpho-Anatomical Characteristics of Leaves and Cones in Juniperus seravschanica Kom.: Studies of Polyphenolic Parenchyma Cells, Secretory Tissues, Sclereids and Tracheids

Conifers are long-lived species that cope with multiple abiotic and biotic stresses. To defend themselves, they have evolved a wide array of morphological, anatomical and chemical traits. Morpho-anatomical traits of Juniperus seravschanica, particularly in male and female cones, have not been studied. Thus, in this survey, these structures were studied to investigate the adaptative traits. The species is frost- and drought-tolerant and grows at a 2200-3800 m altitude on normal, chalky, calcareous, rocky, and mountainous outcrops with other species or as pure patches. The seedlings and young plant leaves were small and needle-like, while the main leaves of adult plants were scale-like and overlapping; there was a conspicuous resin gland (duct) in the outer surface of scale-like leaves secreting a white and sticky resinous substance, particularly in damaged leaves. The epidermis was thick with thicker outer walls and sunken stomata; the hypodermis showed 1-3 layers of lignified cells with a narrow lumen. The palisade parenchyma was observed on both sides. Sclereids, phenolic- and starchy cells were observed in leaves, particularly scale-like ones. Male cones were small with overlapping and decussate scales, in which resin glands (ducts) and phenolic cells were also observed. Similarly, female cones had overlapping and decussate scales converting to fleshy, berry-like, and bluish appearance during development. They revealed the presence of several resin glands, a thick epidermis, phenolic cells in young cones, and numerous sclereid cells in mature cones. Tracheids were narrow in leaves and cones. The features such as high sclerophylly, resin glands, phenolic cells, narrow tracheids, sunken stomata, increasing thickness of the epidermis, cuticle, hypodermis, as well as the presence of palisade parenchyma on both sides enable the species to survive in hard conditions.

Phytochemical composition and biopesticidal potential of Pinus mugo Turra essential oil

Pinus mugo Turra (sensu lato) is an alpine species distributed at high altitudes in the mountains. The species represents a resource for obtaining essential oil (EO). Pinus essential oils (EOs) show great potential as biopesticides in agriculture. To date, there is no comparative study of the EO from various plant parts of P. mugo across the Bulgarian flora. This study aimed to investigate the phytochemical compositions of P. mugo EOs from different plant parts; leaves, twigs, wood, and cones, and evaluate their bioactivity. The botanical pesticides potential of twigs EO against Sitobion avenae, Rhopalosiphum padi, and seeds of weed species Agrostemma githago L., Anthemis arvensis L., Avena fatua L., and Papaver rhoeas L. were tested in Petri dishes. The statistical analysis results showed different EOs yield in different plant parts (0.10–0.63% in leaves, 0.40–1.00% in tips of twigs, 0.1–0.71% in twigs, 0.2–1.43% in wood of one-two year twigs, 0.21–0.6% in male cones, and 0.17% in female cones). The predominant constituents in P. mugo EO were α-pinene, α-phellandrene, β-phellandrene and β-caryophyllene. These constituents were found in all analyzed shrubs from the six populations but in different amounts, depending on the plant part. The tested twigs EO at concentrations of 5%, 4.5%, 3.5%, 2.5%, 1.5%, and 1% had significant insecticidal activity against two aphid species. The efficacy of all concentrations of the EO was 100% on both aphids 24 h after the treatment. The EO demonstrated repellent activity only in high concentrations of 3.5%, 4.5%, and 5% for S. avenae, and 4.5%, and 5% for Rh. padi, respectively. The germination energy, germination, sprouts length, and root length of A. githago, A. arvensis, A. fatua, and P. rhoeas seeds were completely inhibited by low, and high doses (1 µL, 2 µL, 5 µL, 10 µL, and 20 µL) of P. mugo EO. Furthermore, the botanical pesticide capabilities of EOs against six phytopathogens; Alternaria alternata, Botrytis cinerea, Diaporthe nobilis, Fusarium oxysporum, Rhizoctonia solani, and Phytophthora cryptogea were evaluated. The EOs of all investigated parts of the species had strong antimicrobial effect against Salmonella enterica subsp. enterica, and Escherichia coli. The needles tissues extract of P. mugo contained polyphenolic compounds with pronounced antioxidant activity. The findings of this study provide strong support for considering P. mugo EO as a valuable ingredient in the formulation of diverse biopesticides.

Chemical profile, antioxidant and antimicrobial activity of Pinus heldreichii Christ. Distributed in Bulgaria

Pinus heldreichii Christ. (Bosnian pine), a Tertiary relict and Balkan sub-endemic, has not been comprehensively studied for its essential oil (EO) profile and bioactivity of its different plant parts. This study aimed to determine the EO yield, composition and antimicrobial activity from different parts of P. heldreichii at three different populations (mountains) in Bulgaria. Furthermore, the study assessed the antioxidant activities of plant tissue, including leaves (needles), twigs wood, male and female cones. The EOs yield from different plant parts ranged from 0.09 % (leaves) to 0.74 % (wood of twigs), with monoterpenes being the predominant class. Limonene, α-pinene, β-caryophyllene, germacrene D, β-pinene, and β-myrcene were detected in the EO extracted from all analyzed trees. However, these compounds were not found in the EO extracted from all plant parts of the same trees. Four chemical groups (chemotypes) were identified for EO from twigs, and three chemotypes were identified for EO from leaves. The chemotypes were based on the percent ratio of the main EO constituents (>5 %). Leaves tissue showed the highest values in terms of polyphenols and flavonoids, as well as higher ABTS radical scavenging activity, while the highest antimicrobial activity against Staphylococcus aureus subsp. aureus was seen in the EOs obtained from twigs. This is the first study to identify several chemotypes based on leaf and twigs EO of P. heldreichii distributed in Bulgarian flora. Furthermore, the EO of twigs tips (TT), male cones (MC), and wood of one-two-year-old twigs (WT) of the same trees were reported for the first time. The total polyphenol, flavonoid content, and radical scavenging activity of tissues of annual twigs wood and biennial twigs wood, leaf tissue, MC tissue, and the twigs tips tissue is also reported for the first time in the accessible literature. These findings highlight the potential of P. heldreichii to provide EOs with varying compositions and bioactivities, making them suitable for nutraceutical, pharmacological, and potentially food additive applications. Furthermore, the identification of chemotype accessions in this study suggests their selection for the development of new forest crop as a source for natural products with desirable composition and bioactivity.

Phytohormone biosynthesis and transcriptional analyses provide insight into the main growth stage of male and female cones Pinus koraiensis.

The cone is a crucial component of the whole life cycle of gymnosperm and an organ for sexual reproduction of gymnosperms. In Pinus koraiensis, the quantity and development process of male and female cones directly influence seed production, which in turn influences the tree's economic value. There are, however, due to the lack of genetic information and genomic data, the morphological development and molecular mechanism of female and male cones of P. koraiensis have not been analyzed. Long-term phenological observations were used in this study to document the main process of the growth of both male and female cones. Transcriptome sequencing and endogenous hormone levels at three critical developmental stages were then analyzed to identify the regulatory networks that control these stages of cones development. The most significant plant hormones influencing male and female cones growth were discovered to be gibberellin and brassinosteroids, according to measurements of endogenous hormone content. Additionally, transcriptome sequencing allowed the identification of 71,097 and 31,195 DEGs in male and female cones. The synthesis and control of plant hormones during cones growth were discovered via enrichment analysis of key enrichment pathways. FT and other flowering-related genes were discovered in the coexpression network of flower growth development, which contributed to the growth development of male and female cones of P. koraiensis. The findings of this work offer a cutting-edge foundation for understanding reproductive biology and the molecular mechanisms that control the growth development of male and female cones in P. koraiensis.

Essential Oils from Different Parts of Azorean Cryptomeria japonica (Thunb. ex L.f.) D. Don (Cupressaceae): Comparison of the Yields, Chemical Compositions, and Biological Properties

Azorean Cryptomeria japonica is widely used for local wood production, generating large amounts of aerial-part biomass residues that can be a sustainable source of value-added bioproducts. This comparative study aimed (i) to determine the yield and chemical profile of the essential oils (EOs) extracted by hydrodistillation from Azorean C. japonica foliage, leaves, male cones (MCs), and female cones (FCs), and (ii) to investigate the antimicrobial and brine shrimp lethality (BSL) effects of the obtained EOs and some major components. The EOs yield revealed a wide range (ca. 1–3%, w/d.w.) and their chemical composition, analysed by GC–MS and GC–FID, showed the presence of seventy-one components. Monoterpene hydrocarbons (38–71%) dominated in all the studied EOs, mainly α-pinene (17–45% of total EOs), decreasing as follows: cone EOs > leaf EOs > foliage EOs. Oxygen-containing monoterpenes (mainly terpinen-4-ol) also dominated in cone EOs. Contrariwise, oxygen-containing sesquiterpenes (mainly elemol) and diterpene hydrocarbons (mainly phyllocladene) dominated in foliage/leaf EOs. The studied EOs exhibited activity against Gram-positive bacteria but no activity against Gram-negative bacteria. A similar trend was displayed by α-pinene. Only the cone EOs showed antifungal activity against Penicillium chrysogenum, but this was significantly lower than those of α-pinene and terpinen-4-ol. Moreover, FC EO should also be considered for further investigation due to its high toxicity on BSL bioassay. In conclusion, this study demonstrated the variability of yield, chemical profile, and bioactivities in the EOs from different parts of the Azorean C. japonica, expanding the knowledge of the potentialities of C. japonica aerial-part EOs, particularly the ones from the cone samples.

An integrative view on the systematic position of the cupressophyteCephalotaxus

AbstractWe made an in‐depth review of historical studies of the cupressophyte conifer genusCephalotaxusSiebold & Zucc. with an emphasis on its systematic position. We suggest that the systematic position of the genus is better understood using an integrative approach, so the evolution of phenetic characters is discussed within the context of recent phylogenomics. We propose that the genus should be classified as a separate family Cephalotaxaceae belonging to the clade consisting of Cupressaceae, Cephalotaxaceae, and Taxaceae; the family Cephalotaxaceae is sister to the Taxaceae but not nested within the Taxaceae and is characterized by a unique set of characters including morphology, anatomy, embryology, and chemistry. The family Cephalotaxaceae shows transitional characters between the Cupressaceae and the Taxaceae; the family possesses female cones with a primary cone axis bearing 5–8 pairs of decussate bracts, which is similar to the typical female cones of the Cupressaceae, on the one hand, and may have given rise to the reduced female cone of the Taxaceae with one terminal ovule partially or completely enclosed in a fleshy aril. In parallel, the compound male cone of the Cephalotaxaceae evolved into the seemingly “simple” male cones of the Taxaceae by means of reduction, elimination, and fusion.

Multivariate analysis of Lower Cretaceous monosulcate pollen from central-western Argentina

Monosulcate pollen grains are an important component of the Mesozoic palynofloras around the world. These type of grains are produced by several groups of plants and because of the morphological similarities among them, their taxonomic determination is difficult. Currently, there is scarce information about morphological differences of monosulcate pollen grains and this makes their botanical affinity in fossil specimens challenging. In this work, we analyzed statistically the morphological features of monosulcate fossil pollen grains recovered from six palynological assemblages from the Lower Cretaceous Lagarcito Formation of central-western Argentina. We used our own fossil dataset and data from the description of monosulcate pollen grains published from Cretaceous cycadalean in situ male cones from Patagonia. Furthermore, morphological variables from selected living species were added to support the analysis. According to our results, two main groups with clear morphological features were characterized among fossils. The use of an extant dataset allowed us to support the exine sculpture as an important variable when characterizing fossil pollen grains. Finally, our fossil dataset showed similarities with the in-situ pollen grains from the cycadalean cone species Androstrobus munku and Androstrobus patagonicus. This work is the first attempt to identify different morphological types among fossil monosulcate pollen grains recovered from the Lagarcito Formation of central-western Argentina. Our results will contribute to elucidate morphological variations in fossil pollen grains and may improve future taxonomic studies.

Genotypic and environmental effect on male flower production in Cupressus sempervirens clones and selection of genotypes with reduced pollen emission.

Common cypress (Cupressus sempervirens L.) is widespread in the Mediterranean area and is frequently planted as ornamental tree in parks and gardens. Like other species of Cupressus, common cypress releases a significant amount of the total annual airborne pollen in most regions and is known as responsible for winter pollinosis. Although variation in the production and release of pollen has been observed among C. sempervirens trees growing in urban areas, no information is available on effects due to genotype × environment interaction on this trait. In this study more than 150 C. sempervirens clones were analyzed for two to four consecutive years in clonal orchards situated in central Italy to evaluate variations in the production of male cones. Variance component ANOVA underscored an important genetic control of male flowering, with high repeatability (from 0.80 to 0.95) found in single environments. Analysis for combined sites or years (in a single site) showed significant effect of environment and genotype × environment interaction on the total variance. Intra-trait genetic correlations between environments were moderate to high (from 0.40 to 0.92), which indicates that male cone production of clones is fairly consistent across years and sites. Of the 10 clones characterized by the lowest mean male cone production, three showed good stability across environments based on the linear regression coefficient and Wricke's ecovalence. The mean cone production of these 10 clones was 5 to 10 times lower than the mean production observed in the same environment. These clones have both ornamental and hypoallergenic traits and hold promise for designing green spaces with low allergy impact.

The ultrastructure of in situ araucarian pollen from the male cone Callialastrobus sousai, Lower Cretaceous of Catefica, Lusitanian Basin, western Portugal

Pollen morphology and ultrastructure are described for fossil pollen of the Araucariacites and Callialasporites types extracted from a Callialastrobus sousai pollen cone previously reported from the Lower Cretaceous Almargem Formation near the village of Catefica, in the Estremadura region, western Portugal. Pollen grains were studied with transmitted light and scanning and transmission electron microscopy. The pollen grains are medium-sized, being smaller and with a thicker exine in the Callialasporites type. Both pollen types appear inaperturate, although both polar regions are represented by a thinner exine. The exine sculpture (granulate/microechinate) and ultrastructure (granular sexine and lamellate/homogeneous endexine) are generally the same in Araucariacites- and Callialasporites-type grains. Saccus-like structures in the Callialasporites-type pollen are formed by loosely arranged endexine lamellae, while Araucariacites-type pollen is asaccate. The exine structure of the Araucariacites- and Callialasporites-type grains also agrees well with that of known araucariaceous pollen.

Dissection of the Inner Female and Male Cone Differentiation Mechanisms at Different Development Stages in Masson’s Pine (Pinus massonianaLamb.) by RNA-Seq Techniques

The differentiation of male and female cones is important for growth and reproduction for Masson’s pine (Pinus massonianaLamb.). The inner regulation mechanisms of the male and female cones differentiation will helpful for Masson’s pine breeding programs. In order to dissection molecular mechanisms ofP. massonianadifferentiation, male and female cones of early, middle and late development stages were used for comprehensive transcriptomic analysis and quantitative reverse transcriptase PCR (qRT-PCR) verifications. The total numbers of unigenes were 81,850, and mean length was 812 bp in transcriptome analysis. Gene function classification by GO analysis showed that main difference was found mainly in 3 processes, including biological process. KEGG classification showed that differential expressed genes (DEGs) were belong to metabolic pathways and transcriptional regulations. 10 DEGs expression, including flower-like protein (PmTFL), Floricaula (PmFL), APETALA2-related transcription factor2 (PmAP2) that appeared to have central roles in response to cones differentiation was verified via qRT-PCR. The transcriptomic analysis revealed difference of male and female cones differentiation were mainly related to biosynthesis of secondary metabolites, metabolic pathways genes and AP2 transcription factors. These results showed that inner mechanisms of male and female cones differentiations are related to transcriptional regulation of metabolic pathways and helpful for further selection and breeding programs ofPinus massonianaLamb.

A review of the Hirmeriellaceae (Cheirolepidiaceae) wood

Summary The Hirmeriellaceae are an extinct family of Mesozoic conifers. Their foliage has been described in the genera Brachyphyllum, Frenelopsis, Pseudofrenelopsis, etc., while their pollen corresponds to the genus Classopollis, the male cones to e.g. Classostrobus or Tomaxellia and the female scales were named Hirmeriella and Paraucaria, for example. Reproductive structures are necessary for a definite identification of the family. Such fossils are rarely found in connection with mature secondary xylem. As a result, very little is known about the wood anatomy of the Hirmeriellaceae. This work reviews available evidences, either from connections between wood and reproductive structures typical for the Hirmeriellaceae or from associations of such fossils within Mesozoic rocks. Connection cases are rare and are reported only for the Cretaceous and for genera Frenelopsis and Pseudofrenelopsis. Association cases are more numerous; however, they are also poorly distributed in time, being reported mostly from two intervals only, the latest Triassic–earliest Jurassic and the Early Cretaceous. Wood data are also poorly distributed taxonomically with most of them being from the frenelopsids. The fossil genera Agathoxylon, Brachyoxylon, Protocupressinoxylon and Protopodocarpoxylon were used for wood fossils which are more or less safely related to the Hirmeriellaceae. However, only the first two seem to have been rightly used, the first usually for juvenile or small diameter wood, the second for more mature wood. Even if there seems to be a privileged link between Brachyoxylon and the Hirmeriellaceae, it cannot be said to be exclusive.

Evaluation of thermoregulation of different pine organs in early spring and estimation of heat reward for the western conifer seed bug (Leptoglossus occidentalis) on male cones.

The western conifer seed bug (WCSB, Leptoglossus occidentalis) is a pest of many pine species and is invasive worldwide. WCSB directly and indirectly deteriorates pine nut production by sucking seeds from cones. Currently, researchers think that WCSBs search for food by a combination of cues from visible light, infrared radiation, and chemicals such as monoterpenes. Some research revealed that WCSBs prefer larger cones, and it was thought that WCSBs suck seeds from and obtain more heat on larger cones. However, in early spring, we observed that most WCSBs gathered on male cones rather than on female cones and young cones. We hypothesized that male pine cones were warmer than female cones and needles, and WCSBs sucking male cones may receive more heat. To test these hypotheses, we measured spectral reflectance with a hyperspectral sensor and temperature of pine organs with tiny thermocouples, and the data were analyzed by a heat budget model. Our results revealed that male cones were significantly warmer and more reflective than female cones and needles, which may attract WCSBs. These results supported our hypothesis that WCSBs on male cones were warmer than those on other organs. This study will help further understanding of WCSBs and the adaptive value of pine cone colors.

Differentially Expressed Transcription Factors during Male and Female Cone Development in Pinus halepensis

The molecular regulation of induction and development of reproductive organs is well established in angiosperms, while it is slowly accumulating in gymnosperms. Here, we conducted comparative transcriptomic profiles at different stages of male and female cone development in Pinus halepensis. Our aim was to reveal transcription factor encoding genes involved in reproductive induction and development. For accurate developmental stage identification, histological analysis preceded the molecular analysis. The flowering induction genes FT/TFL were expressed mainly at the late developmental stages of the male cone, suggesting involvement in vegetative bud dormancy instead of flowering induction. The male cone development was associated with the expression of the C-class PhMADS2, and the B-class genes PhDAL11 and PhDAL13, while the female cone development was associated with the expression of the C-class MADS1 and DAL14 genes. This study adds valuable knowledge to the profile of transcription factors and MADS-box genes regulating cone development in gymnosperms.

Two new species of Pharaxonothinae beetles (Coleoptera: Erotylidae) inhabiting cones of the cycad Ceratozamia santillanii Prez-Farr. amp; Vovides (Cycadales: Zamiaceae) in Mexico.

Two beetles, Ceratophila (Vovidesa) chipjonesi, new species, and Pharaxonotha perezi, new species, (Coleoptera: Erotylidae: Pharaxonothinae) are described from the male cones of the New World cycad Ceratozamia santillanii Prez-Farr. Vovides (Cycadales: Zamiaceae). Morphological analysis and keys are provided for distinguishing these from related beetles inhabiting Ceratozamia in Mexico.

The Cycas genome and the early evolution of seed plants

Cycads represent one of the most ancient lineages of living seed plants. Identifying genomic features uniquely shared by cycads and other extant seed plants, but not non-seed-producing plants, may shed light on the origin of key innovations, as well as the early diversification of seed plants. Here, we report the 10.5-Gb reference genome of Cycas panzhihuaensis, complemented by the transcriptomes of 339 cycad species. Nuclear and plastid phylogenomic analyses strongly suggest that cycads and Ginkgo form a clade sister to all other living gymnosperms, in contrast to mitochondrial data, which place cycads alone in this position. We found evidence for an ancient whole-genome duplication in the common ancestor of extant gymnosperms. The Cycas genome contains four homologues of the fitD gene family that were likely acquired via horizontal gene transfer from fungi, and these genes confer herbivore resistance in cycads. The male-specific region of the Y chromosome of C. panzhihuaensis contains a MADS-box transcription factor expressed exclusively in male cones that is similar to a system reported in Ginkgo, suggesting that a sex determination mechanism controlled by MADS-box genes may have originated in the common ancestor of cycads and Ginkgo. The C. panzhihuaensis genome provides an important new resource of broad utility for biologists.

Transcriptional Regulation of Pine Male and Female Cone Initiation and Development: Key Players Identified Through Comparative Transcriptomics.

With long reproductive timescales, large complex genomes, and a lack of reliable reference genomes, understanding gene function in conifers is extremely challenging. Consequently, our understanding of which genetic factors influence the development of reproductive structures (cones) in monoecious conifers remains limited. Genes with inferred roles in conifer reproduction have mostly been identified through homology and phylogenetic reconstruction with their angiosperm counterparts. We used RNA-sequencing to generate transcriptomes of the early morphological stages of cone development in the conifer species Pinus densiflora and used these to gain a deeper insight into the transcriptional changes during male and female cone development. Paired-end Illumina sequencing was used to generate transcriptomes from non-reproductive tissue and male and female cones at four time points with a total of 382.82 Gbp of data generated. After assembly and stringent filtering, a total of 37,164 transcripts were retrieved, of which a third were functionally annotated using the Mercator plant pipeline. Differentially expressed gene (DEG) analysis resulted in the identification of 172,092 DEGs in the nine tissue types. This, alongside GO gene enrichment analyses, pinpointed transcripts putatively involved in conifer reproductive structure development, including co-orthologs of several angiosperm flowering genes and several that have not been previously reported in conifers. This study provides a comprehensive transcriptome resource for male and early female cone development in the gymnosperm species Pinus densiflora. Characterisation of this resource has allowed the identification of potential key players and thus provides valuable insights into the molecular regulation of reproductive structure development in monoecious conifers.

Multi-centennial phase-locking between reproduction of a South American conifer and large-scale drivers of climate.

Climate forcings determine the episodic occurrence of local climate anomalies that trigger the occurrence of masting events (massive, synchronized and intermittent seed production by perennial plants). This suggests some kind of phase-locking of the reproductive cycles of individual plants to the climatological cycle, thus further reinforcing reproductive synchrony and the Moran effect. We propose a dendrochronological approach to filter out the long-term direct effects of climate on tree radial growth and temporal reproductive effort by sex by using actual trees as climatic controls to reconstruct masting events in Araucaria araucana, a long-lived dioecious masting conifer. In this way, we developed a multi-century-long tree masting reconstruction for South America using female-male radial growth determined by differences in timing and magnitude of the reproductive effort between sexes. We provide evidence for a regional synchronizing mechanism of masting which is drought induced by strong cold La Niña phases of El Niño/Southern Oscillation (ENSO) amplified by the positive phases of the Southern Annular Mode (SAM) that activate both female and male cone bud formation during year -2 before seed fall; that is, a long-term phase-locking between the ENSO cycle and the reproductive cycle modulated by the strength of SAM. In addition, our regional index of masting frequency showed its maximum during the late twentieth century relative to the previous centuries, suggesting that the species is currently at its maximum masting frequency concurrent with a period of enhanced temperature and drought conditions in Patagonia, probably driven by the positive phase of the SAM.