Male Inflorescences Research Articles

Drought constrains acorn production and tree growth in the Mediterranean holm oak and triggers weak legacy effects

Droughts are becoming more frequent in the Mediterranean basin due to warmer conditions. Droughts negatively impact forests growth for several years, often generating negative legacies or carryover effects. However, these legacies differ among tree species, sites and drought characteristics and have been mainly studied considering tree growth or canopy greenness, but ignoring reproductive phenomena. Here, we compare the legacy effects of drought on acorn and male inflorescence production and radial growth by using a 19-year series of 150 Quercus ilex individuals in three stands located in north-eastern Spain. We evaluate the relationships between monthly climate variables, tree-ring width, acorn production and male inflorescence production. For the two driest years considered (2005 and 2012), when very few acorns were produced, we did not find negative legacy effects on acorn production in the three years following droughts. The production of male inflorescences did not show any significant legacy after drought, although its annual variation was related to the climatic conditions of the year before acorn ripening. Acorn production was higher than expected for some of these years, apparently following the pattern of tree growth recovery with a certain lag. This compensatory response of acorn production differed between the two analysed droughts, in accordance with different conditions of drought timing and post-drought climate conditions. Even though few negative legacy effects of growth and acorn production were found, we confirmed the negative effect of drought stress on tree growth and acorn production, linked to dry winter conditions. Our findings confirm that drought features (timing, duration, intensity) and post-drought climate conditions influence tree growth and reproduction legacies.

Ilex danxiaensis (Aquifoliaceae), a Distinct New Tree Species Endemic to Danxia Mountain in Guangdong Province, China, Based on Molecular and Morphological Evidence

Many holly species are dominant species in evergreen broad-leaved forests, and they play an important role in the formation and maintenance of forest ecosystems in tropical and subtropical regions. Here, a new holly species (Ilex danxiaensis K. W. Xu & Q. Fan) of Aquifoliaceae was discovered from Guangdong, China, when conducting biodiversity investigations in the Danxia landform. We inferred the phylogenetic position of the new species based on sequences from three nuclear markers, namely internal transcribed spacer (ITS), external transcribed spacer (ETS), and chloroplast glutamine synthetase gene (nepGS). The results demonstrated a close relationship among the new species and members of I. sect. Lioprinos. The inferred phylogenetic position of the new species is also supported by morphological evidence that all of these species are characterized by having axillary cymes inflorescences and abaxially 1-sulcate pyrenes. However, the new species can be distinguished from others by having puberulent branchlets, petioles, peduncles, and pedicel; (1–)2–3-flowered cymes of male inflorescences; 1-flowered cymes of female inflorescences; ciliate sepals, 4-merous flowers, pink or white female flowers; and 4 pyrenes.

A new species of Gymnostoma (Casuarinaceae) present during the Neogene aridification of Southern Australia

The Miocene to Pliocene silcrete sediments at Stuart Creek in South Australia have been reported for about 50 years, but no species have been formally described. One of the most common macrofossils has been reported in varying ways as belonging to the family Casuarinaceae. New techniques allow for detailed investigation and identification of the genus and a new species. The macrofossils represent vegetative branchlets, female infructescences and probable male inflorescences of a single species of Gymnostoma, here named G. stuartii. This is the sixth fossil species of Gymnostoma described and is by far the most recent. This species is distinguished from other described living and fossil species by a combination of the shape and angle of the leaf tip, the shape of the branchlet in cross section, the number of nodes in the female infructescence, the shape of the bracts and the protrusion of the bracteoles in the female infructescence. This new fossil species, together with the other two fossil Gymnostoma species already known from Australia, suggests that Gymnostoma may have been quite diverse in Australia during the Cenozoic, and also that their extinction from southern Australia occurred after a long persistence to near the end of the Cenozoic. This extinction was possibly as part of the general transition of the vegetation from scleromorphic to xeromorphic.

Flowering and fruiting of Tape Seagrass Enhalus acoroides (L.f.) Royle from the Andaman Islands: observations from inflorescence buds to dehiscent fruits

Seagrass phenophases are crucial in understanding their reproductive biology but are seldom documented. We studied flowering and fruiting phenophases of Enhalus acoroides from a mixed-species intertidal seagrass meadow in Ritchie’s archipelago, Andaman Islands, India. The estimated mean densities of pistillate and staminate flowers were 16.0 ± 12.0/ m2 and 12.7 ± 7.3/ m2, respectively. We observed the bloom of free-floating male flowers (961.7 ± 360.4/ m2) during the spring low tides (at mean sea surface temperature ~30°C). Seagrass cover, shoot density, and canopy height of E. acoroides, along with flowering densities, showed a zonal variation within the sampled meadow. We report the first-time observations of several phenophases of E. acoroides, such as female inflorescence buds, male inflorescence, a bloom of released male flowers, pollination, and fertilized flowers from the Indian waters. We also report the prevailing threats to seagrass meadows, such as meadow scarring done by boat anchorage in the Andaman Islands.

A review study on the antioxidant and antimicrobial activities of Pandanus Odoratissimus L. male inflorescence

A review study on the antioxidant and antimicrobial activities of Pandanus Odoratissimus L. male inflorescence

Microscopic and phytochemical examination of the male inflorescence of Pandanus odoratissimus L.

Microscopic and phytochemical examination of the male inflorescence of Pandanus odoratissimus L.

Plant growth traits and allergenic potential of Ambrosia artemisiifolia pollen as modified by temperature and NO2

Ongoing global warming favors the spread of thermo-tolerant plant species including plants with a high allergenic risk such as common ragweed (Ambrosia artemisiifolia). To assess effects of temperature increase on plant traits and biochemical processes potentially associated with allergenicity, we performed a phytotron chamber experiment which included two levels of temperature (control, elevated by 4 °C) simulated at 10 min resolution, and NO2 (0 ppb, 80 ppb added at a constant rate), respectively, and their combination in a full factorial design. The aim was to evaluate effects of temperature on various parameters related to ragweed allergenicity relative to effects of a known enhancer of allergenicity such as NO2, including the interaction between temperature and NO2. As plant growth parameters, we assessed plant height, male inflorescence size, start and end date of pollen release as well as average pollen release per inflorescence. As pollen traits, we determined pollen allergenicity by dot blot and biochemical factors that may enhance (oxidative stress indicators) or attenuate (flavonoids) pollen allergenicity. We tested the hypotheses that elevated temperatures do not increase the stress level of thermophilic ragweed and thus do not affect allergenicity, whereas NO2 increases allergenicity independent of temperature. Two-way ANOVA results revealed that elevated temperature significantly enhanced the plant height, the size of male inflorescences, and the duration of pollen release, in addition, significantly delayed pollen release independent of NO2. Pollen release per inflorescence was significantly induced by elevated NO2. As single factors, elevated temperature or NO2 affected allergenicity, moreover, the combined treatment of elevated temperature plus NO2 resulted in increased levels of NAD(P)H oxidase activity, H2O2 content, and highest allergenicity. Concentrations and composition of pollen flavonoids were significantly changed by NO2. Irrespective of treatments, pollen flavonoids were dominated by quercetins, but their overall composition was significantly changed by treatments. Flavonoids from lower temperature treatments showed significantly reduced allergen-IgE binding activities. A common trend observed was that elevated temperatures particularly in combination with NO2, increased the pollen allergenicity.

Fine‐scale temporal dynamics of flower visitors sheds light on insect‐assemblage overlap between sexes in a dioecious Ecuadorian palm

AbstractDioecious plants generally display sexual dimorphism in male and female floral traits, potentially attracting slightly different pollinator communities. The sharing of common floral visitors between male and female flowers and their timing of visits to both sexes is of critical importance to ensure plant's reproductive success. Palm inflorescences are visited by abundant and diverse insect communities, yet the temporal patterns of insect visits on both sexes remain poorly known. We characterized the composition of a community of flower‐visiting arthropods associated with the dioecious ivory palm (Phytelephas aequatorialis, Spruce) in a pre‐montane forest of Ecuador. We monitored the temporal variations in insect visits along the flowering of 12 inflorescences (eight female and four male) using interception traps recovered every 4 h. We report 59 morphospecies in the arthropod community, dominated by three beetle families: Staphylinidae, Nitidulidae, and Curculionidae. Male inflorescences were more abundantly visited than female, but visitors of the later were taxonomically more diverse. Among the 16 pollinator candidates identified, nine visited both inflorescence sexes synchronously at dusk /night whereas the others did so asynchronously during the day. Our study provides new insights into the pollination mechanism ofP. aequatorialis.We found evidence of differential pollinator attraction between floral sexes, which may be explained by the sexual dimorphism of both flowers. Synchronicity in dusk/night visits of both inflorescence sexes suggests a sexual synchronization of the signal used to attract pollinators.Abstract in Spainsh is available with online material

Piper puerense, a new species of Piperaceae from Yunnan, China

Piper puerense (Piperaceae), a new species from Yunnan, China, is here described and illustrated. Detailed morphological comparisons between the newly discovered species and other members of Piper indicate that Piper puerense is similar to Piper curtipedunculum, from which it differs in that stems of the new species are densely pubescent when young, glabrous when mature, leaf blades ovate, 8.5–12 cm × 4.3–6.5 cm, spike peduncle 15 mm long, nearly two times larger than the petiole; female inflorescence 12–18 cm long, male inflorescence 20–30 cm long, fruit obovate in shape, 1.0–1.5 mm in diameter.

Dependence of flower-bearing on trunk size and trunk origin in four tree species of the subgenus Quercus

ABSTRACT We investigated the flower-bearing properties of four sympatric oak species in the subgenus Quercus commonly grown in semi-natural forests in western Honshu Island, Japan. Quercus variabilis and Quercus acutissima belong to the section Cerris and Quercus serrata and Quercus aliena belong to the section Quercus. The timing and pattern of flower-bearing varied among the four oaks, but were synchronized between the male and female inflorescences within each species. Trunk size was the primary factor affecting the flower-bearing properties; more flowers were borne on thicker trunks. Threshold trunk sizes for flower-bearing, below which no flowers were borne, were identified in the two Cerris section oak species; in contrast, the two Quercus section oak species bore flowers even on the smallest trunks. The smallest flower-bearing trunk sizes of the Quercus section oaks were extremely small compared with the other tall tree species distributed in the temperate zone of Honshu Island. The flowering probability was not clearly influenced by whether the stem originated from a seedling or a sprout, except for the male inflorescences of Q. aliena, which rather showed a positive relationship between sprout-origin and flower-bearing. Thus, no trade-off relationship between sprouting and flowering was observed.

Functional Significance of Thread‐Like Appendix on Arisaema urashima (Araceae) Attracting Fungus Gnat Pollinators

Despite the longstanding speculation, the functional significance of the unique long, filiform appendices commonly seen in many fly-pollinated flowers remains unclear. In this study, we conducted a removal experiment of the thread-like appendix in Arisaema urashima to examine its functional significance. The present study provides strong evidence for the attraction role of the thread-like appendix targeting its primary pollinators, the Mycetophila fungus gnats. Our study elucidates a century-old conundrum in pollination ecology: the functional role of the long thread-like appendix in fungus gnat-pollinated flowers. Photo 1. The Japanese endemic flowering plant, Arisaema urashima, which possesses a spectacular thread-like sterile appendage, provided us with an opportunity to explore how the filiform structure affects pollination. Photo credit: Emiko Kato. Photo 2. Similar to many other Arisaema species, A. urashima traps fungus gnats to ensure pollination. In male inflorescences, the gnats accumulate increasing numbers of pollen grains (top right) while struggling to escape until finally locating and exiting through a small opening (left) at the base of the spathe. However, female morphs lack exit holes in their spathes. Therefore, the trapped gnats usually cannot escape until death (bottom right). Photo credit: Kenji Suetsugu. Photo 3. The lack of an exit hole on the female spathe increases the time spent by fungus gnats around the florets, resulting in more pollen deposition. Consequently, high fruit sets are often seen even in Arisaema urashima plants inflorescences with only one fungus gnat individual trapped. Photo credit: Eiji Ishitani. These photographs illustrate the article “Thread-like appendix on Arisaema urashima (Araceae) attracts fungus gnat pollinators” by Kenji Suetsugu, Hiroki Nishigaki, Shigeki Fukushima, Eiji Ishitani, Satoshi Kakishima, and Masahiro Sueyoshi published in Ecology. https://doi.org/10.1002/ecy.3782

Assessment on Pollen Carrying Capacity and Pollen Viability of Elaeidobius kamerunicus (Coleoptera: Curculionidae)

Oil palm, also known as Elaeis guineensis Jacq (Arecales: Arecaceae), depends greatly on the pollinating weevil Elaeidobius kamerunicus (Coleoptera: Curculionidae) for fruit production. Despite this, information on the pollen-carrying capacity of E. kamerunicus is still lacking. This study assessed the pollen-carrying capacity (PCC) and pollen viability (PV) of E. kamerunicus in two oil palm plantations with different soil types in Sabah, Malaysia. The pollination contribution of adult weevils to sex and body surface area (BSA) was also investigated. Adult weevils were collected from both male and female inflorescences and kept in microcentrifuge tubes containing pollen grain germination medium solutions to assess their pollination contribution. Results indicated a significant difference for BSA between sexes. Mann-Whitney test showed greater PCC for male weevils than female weevils for FELDA Sahabat and Long Danau from male inflorescence. PCC for female inflorescence showed no significant differences between male and female weevils for both oil palm plantations. PV showed no significant difference between sexes but differed significantly between oil palm plantations due to better soil quality in clay textured soil. Based on the results, pollination contribution by male adult weevils was greater than female adult weevils for both plantations.

Phytochemical and biological investigations on the pollen from industrial hemp male inflorescences

Cannabis sativa L. belongs to the Cannabaceae family and includes annual, robust, fast-growing and generally dioecious plants. Industrial hemp, and particularly the inflorescences, has been recently recognized as important source of bioactive extracts with antioxidant and antimicrobial effects. The goal of the present study was to explore botanical, phytochemical, and biological properties of water and hydroalcoholic hemp pollen extracts from male inflorescences. The extracts from hemp pollen were found rich in phenolic compounds, such as hydroxytyrosol, coumaric acid, and hesperitin. The phenolic profile was also consistent with the observed scavenging/reducing, enzyme inhibitory, and antimicrobial properties of the extracts. Regarding the antimicrobial effects, Escherichia coli, Trycophyton rubrum, and T. tonsurans were the most sensitive to growth inhibitory effects (MIC values: 9.92–79.37 µg/mL) of the extracts. Whereas, null effects on prostate PC3 and myocyte C2C12 cell viability, in the range 1–1000 µg/mL, are consistent with MIC values and suggest extracts’ biocompatibility. The experimental data obtained, which are not reflected in the literature as the topic of hemp pollen is almost completely unexplored, confirm the innovativeness of a product obtained directly from bees, which in the face of greater variability and complexity can reserve promising applications in food, pharmaceutical, and cosmetic sectors.

Vibrational response of the male ‘peter’ pistachio branch organs to facilitate artificial pollination

Artificial pollination may be a promising practice to both improve pistachio fruit production by mitigating the losses caused by phenological gaps or by adverse meteorological events and establish new production areas. Artificial pollination requires large quantities of pollen and manual collection is not economically viable. Mechanical capture of pollen, for subsequent storage and application, could achieved in two ways: by releasing mature pollen from the inflorescences and capturing it in the air, or detaching mature male inflorescences for taking pollen in laboratory. In this work, the dynamic behaviour of branches of the male ‘Peter’ variety was analysed under controlled laboratory conditions. A wide range of vibration frequencies was used for branch excitation, and the responses of the stem and its inflorescences were analysed. The stem and inflorescences had clearly differentiated dynamic responses according to the vibration frequency. The stem attained maximum acceleration transmissibility values at specified frequency values (8, 13.5, 20.5–22 Hz). At these values, the vibration applied amplified the stem movement and could clearly contribute to pollen release to the atmosphere. At the highest frequency values (45 Hz), the stem damped the vibration, but the inflorescences amplified the response. In the 54–59 Hz range, the inflorescences amplified the acceleration received by an average 5-fold. In this range, detachment of the inflorescences is facilitated without exciting the stems. Thus, current commercial trunk shakers must be adapted if they are used to collect pollen from pistachio trees owing to the higher transmission values of trees without leaves. • Stem and male inflorescences of the Peter variety have a different dynamic response. • Precise vibration frequency applied to branch enables a selective organ excitation. • Trunk shakers can be adapted for mass pollen detachment. • Absence of leaves during the pollination period may increase damage to shaken trees .

Non-Invasive and Confirmatory Differentiation of Hermaphrodite from Both Male and Female Cannabis Plants Using a Hand-Held Raman Spectrometer

Cannabis (Cannabis sativa L.) is a dioecious plant that produces both male and female inflorescences. In nature, male and female plants can be found with nearly equal frequency, which determines species out-crossing. In cannabis farming, only female plants are preferred due to their high yield of cannabinoids. In addition to unfavorable male plants, commercial production of cannabis faces the appearance of hermaphroditic inflorescences, species displaying both pistillate flowers and anthers. Such plants can out-cross female plants, simultaneously producing undesired seeds. The problem of hermaphroditic cannabis triggered a search for analytical tools that can be used for their rapid detection and identification. In this study, we investigate the potential of Raman spectroscopy (RS), an emerging sensing technique that can be used to probe plant biochemistry. Our results show that the biochemistry of male, female and hermaphroditic cannabis plants is drastically different which allows for their confirmatory identification using a hand-held Raman spectrometer. Furthermore, the coupling of machine learning approaches enables the identification of hermaphrodites with 98.7% accuracy, whereas both male and female plants can be identified with 100% accuracy. Considering the label-free, non-invasive and non-destructive nature of RS, the developed optical sensing approach can transform cannabis farming in the U.S. and overseas.

Adjacent forest moderates insect pollination of oil palm

Natural habitat plays a role in many agroecosystems as a source of pollination services and other ecological spillover, but these effects are largely unquantified in oil palm (Elaeis guineensis), a globally important crop linked to deforestation. In a field experiment in Sumatra, Indonesia, we manipulated floral visitor access to female oil palm inflorescences over a 100 m distance gradient from forest into oil palm and sampled insects with sticky traps placed above male and female inflorescences. Full exclusion of floral visitors decreased mean oil palm fruit set to 12%, demonstrating that insect pollination was necessary to maintain favorable fruit set and yield. Treatment group means of fruit set under open pollination (62%) and when excluding large (>1.4 mm diameter) organisms (72%), did not differ significantly from open pollination augmented with hand pollination (61%), suggesting no difference in pollen limitation. In contrast, when we examined change in fruit set with distance from forest, we found a significant trend of higher fruit set in oil palms closer to the forest when large organisms were excluded, which increased estimated fruit set at the forest edge to 87%, compared to open-pollinated palms (70%). This trend with distance from forest was absent when we fully excluded floral visitors, showing that the effect of forest was not likely due to an abiotic gradient (e.g., changing soil nutrients). Of the arthropod taxa collected from sticky traps, Drosophilidae (Diptera) and Gelechiidae (Lepidoptera) decreased and increased with distance from forest, respectively. The taxa Elaeidobius kamerunicus (Coleoptera: Curculionidae), Gelechiidae, and the families Thripidae and Phlaeothripidae (Thysanoptera) were abundant on both male and female inflorescence sticky traps. Elaeidobius kamerunicus, an introduced oil palm pollinator, had the only significant relationship with fruit set. Our results confirm pollination by insects as a key ecosystem service for oil palm production. Although further work is needed to clarify the relationship between fruit set, biodiversity, and distance from forest, we speculate that excluding large organisms could have increased fruit set closer to forest by mediating interactions between pollinators, forest predators, and farm mesopredators. Understanding the relationships between nearby forest and pollination services could better connect oil palm production to its landscape context and associated biodiversity. This would be important for landscape-scale conservation planning that considers both the ecosystem service needs and ecological impacts of oil palm agriculture.

Transcriptome Analysis of Morus alba L. Flower Reveals Important Genes of Floral Sex Differentiation

Mulberry (Morus alba L.) is a perennial woody plant with significant economic benefits and ecological value. The floral character of mulberry has an important impact on the yield and quality to its fruits and leaves. However, little is known about the molecular mechanism of mulberry floral differentiation still now. The transcriptome data were obtained via Illumina HiSeq high-throughput sequencing from male and female inflorescences of the monoecious mulberry. A total of 26.21 Gb clean data were obtained, and as many as 100,177 unigenes with an average length of 821.66 bp were successfully assembled. In comparative-omics analysis, 1717 differentially expressed genes (DEGs) were identified between male and female flowers and only a quarter of the DEGs were highly expressed in female flowers. The KEGG pathway enrichment analysis revealed that DEGs were involved in glucose and lipid metabolism, hormone signal transduction, and the regulation of related transcription factors. In addition, many DEGs related to flower development and plant sex differentiation have also been detected, such as PMADS1/2, AGAMOUS, FLOWERING LOCUS T (FT), APETALA 2 (AP2), TASSELSEED2 (TS2), and ARABIDOPSIS RESPONSE REGULATOR 17 (ARR17). Finally, the expression patterns of selected 20 DEGs were validated by q-PCR and the results showed that the transcriptome data were highly reliable. This study shows that the differentiation of male and female flowers of mulberry is affected and regulated by multiple factors, with transcription factors and hormone signals playing a key role. Briefly, the current data provide comprehensive insights into the mulberry tree’s floral differentiation as well as a bioinformatics framework for the development of molecular breeding of mulberry.

The first record of Anatrachyntis lunulifera ( ) (Lepidoptera: Cosmopterigidae) in the Ryukyus, Japan

Anatrachyntis lunulifera (Meyrick, 1935) (Lepidoptera: Cosmopterigidae) is distributed in the Pacific region, for example, in Fiji and the Marquesas Islands, and larvae of this species feed on the male inflorescence of Pandanus species. In our study, A. lunulifera was collected from Pandanus odorifer (Forssk.) Kuntze in Amami oshima Island, Okinawa-jima Island, and Miyako-jima Island, the Ryukyus, Japan. This article is the first report of A. lunulifera from Japan, North Pacific. In this study, we have redescribed and illustrated the adult, male and female genitalia of A. lunulifera, and illustrated those of A. incertulella (Walker, 1864), another Pandanus feeder occurring together with A. lunulifera in the Ryukyus, for comparison.

Genetic Structure and Molecular Mechanisms Underlying the Formation of Tassel, Anther, and Pollen in the Male Inflorescence of Maize (Zea mays L.).

Maize tassel is the male reproductive organ which is located at the plant’s apex; both its morphological structure and fertility have a profound impact on maize grain yield. More than 40 functional genes regulating the complex tassel traits have been cloned up to now. However, the detailed molecular mechanisms underlying the whole process, from male inflorescence meristem initiation to tassel morphogenesis, are seldom discussed. Here, we summarize the male inflorescence developmental genes and construct a molecular regulatory network to further reveal the molecular mechanisms underlying tassel-trait formation in maize. Meanwhile, as one of the most frequently studied quantitative traits, hundreds of quantitative trait loci (QTLs) and thousands of quantitative trait nucleotides (QTNs) related to tassel morphology have been identified so far. To reveal the genetic structure of tassel traits, we constructed a consensus physical map for tassel traits by summarizing the genetic studies conducted over the past 20 years, and identified 97 hotspot intervals (HSIs) that can be repeatedly mapped in different labs, which will be helpful for marker-assisted selection (MAS) in improving maize yield as well as for providing theoretical guidance in the subsequent identification of the functional genes modulating tassel morphology. In addition, maize is one of the most successful crops in utilizing heterosis; mining of the genic male sterility (GMS) genes is crucial in developing biotechnology-based male-sterility (BMS) systems for seed production and hybrid breeding. In maize, more than 30 GMS genes have been isolated and characterized, and at least 15 GMS genes have been promptly validated by CRISPR/Cas9 mutagenesis within the past two years. We thus summarize the maize GMS genes and further update the molecular regulatory networks underlying male fertility in maize. Taken together, the identified HSIs, genes and molecular mechanisms underlying tassel morphological structure and male fertility are useful for guiding the subsequent cloning of functional genes and for molecular design breeding in maize. Finally, the strategies concerning efficient and rapid isolation of genes controlling tassel morphological structure and male fertility and their application in maize molecular breeding are also discussed.

Thladiantha longipedicellata (Cucurbitaceae), a new species from Guangxi, China

Thladiantha longipedicellata, a new species of Cucurbitaceae, is described and illustrated from a gorge in southwestern Guangxi, China. It is similar to T. cordifolia and T. grandisepala in its imbricate bracts in the male inflorescence, but it can be chiefly distinguished from both species by having vestigial leaves, longer peduncles and pedicels in the male inflorescence, the shape of male inflorescence, the texture of fruit and female styles split to the base. A character table to distinguish the new species from morphologically similar species as well as color plates for comparison are provided.