-
Plants (Basel, Switzerland) May 2024Understanding the regulation of autotetraploid sterility is essential for harnessing the strong advantages in genomic buffer capacity, biodiversity, and heterosis of...
Understanding the regulation of autotetraploid sterility is essential for harnessing the strong advantages in genomic buffer capacity, biodiversity, and heterosis of autotetraploid rice. miRNAs play crucial roles in fertility regulation, yet information about their reproductive roles and target genes in tetraploid rice remains limited. Here, we used three tetraploid lines, H1 (fertile), HF (fertile), and LF (sterile), to investigate cytological features and identify factors associated with autotetraploid sterility. LF showed abnormal meiosis, resulting in low pollen fertility and viability, ultimately leading to scarce fertilization and a low-seed setting compared to H1 and HF. RNA-seq revealed 30 miRNA-candidate target pairs related to autotetraploid pollen sterility. These pairs showed opposite expression patterns, with differential expression between fertile lines (H1 and HF) and the sterile line (LF). qRT-PCR confirmed that , , and were highly expressed in the anthers of H1 and HF but not in LF, while opposite results were obtained in their targets (, , and ). Haplotype and expression pattern analyses revealed that was specifically expressed in lines with the same haplotype of (the precursor of ) as LF. Furthermore, the Dual-GFP assay verified that inhibited the fluorescence signal of ARPS-GFP. The over-expression of significantly decreased the seed setting rate (59.10%) and pollen fertility (50.44%) of neo-tetraploid rice, suggesting that plays important roles in autotetraploid pollen sterility. This study provides insights into the cytological characteristic and miRNA expression profiles of tetraploid lines with different fertility, shedding light on the role of miRNAs in polyploid rice.
PubMed: 38891270
DOI: 10.3390/plants13111461 -
Plants (Basel, Switzerland) May 2024Pollination in angiosperms depends on complex communication between pollen grains and stigmas, classified as wet or dry, depending on the presence or absence of...
Pollination in angiosperms depends on complex communication between pollen grains and stigmas, classified as wet or dry, depending on the presence or absence of secretions at the stigma surface, respectively. In species with wet stigma, the cuticle is disrupted and the presence of exudates is indicative of their receptivity. Most stigma studies are focused on a few species and families, many of them with self-incompatibility systems. However, there is scarce knowledge about the stigma composition in Fabaceae, the third angiosperm family, whose stigmas have been classified as semidry. Here we report the first transcriptome profiling and DEGs of L. styles and stigmas from autofertile (flowers able to self-fertilize in the absence of manipulation, whose exudate is released spontaneously) and autosterile (flowers that need to be manipulated to break the cuticle and release the exudates to be receptive) inbred lines. From the 76,269 contigs obtained from the de novo assembly, only 45.1% of the sequences were annotated with at least one GO term. A total of 115,920, 75,489, and 70,801 annotations were assigned to Biological Process (BP), Cellular Component (CC), and Molecular Function (MF) categories, respectively, and 5918 differentially expressed genes (DEGs) were identified between the autofertile and the autosterile lines. Among the most enriched metabolic pathways in the DEGs subset were those related with amino acid biosynthesis, terpenoid metabolism, or signal transduction. Some DEGs have been related with previous QTLs identified for autofertility traits, and their putative functions are discussed. The results derived from this work provide an important transcriptomic reference for style-stigma processes to aid our understanding of the molecular mechanisms involved in faba bean fertilization.
PubMed: 38891252
DOI: 10.3390/plants13111443 -
Scientific Reports Jun 2024Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most...
Biological invasions threaten global biodiversity, altering landscapes, ecosystems, and mutualistic relationships like pollination. Orchids are one of the most threatened plant families, yet the impact of invasive bees on their reproduction remains poorly understood. We conduct a global literature survey on the incidence of invasive honeybees (Apis mellifera) on orchid pollination, followed by a study case on Australian orchids. Our literature survey shows that Apis mellifera is the primary alien bee visiting orchids worldwide. However, in most cases, introduced honeybees do not deposit orchid pollen. We also test the extent to which introduced honeybees affect orchid pollination using Diuris brumalis and D. magnifica. Diuris brumalis shows higher fruit set and pollination in habitats with both native and invasive bees compared to habitats with only introduced bees. Male and female reproductive success in D. magnifica increases with native bee abundance, while conversely pollinator efficiency decreases with honeybee abundance and rises with habitat size. Our results suggest that introduced honeybees are likely involved in pollen removal but do not effectively deposit orchid pollen, acting as pollen wasters. However, Apis mellifera may still contribute to pollination of Diuris where native bees no longer exist. Given the global occurrence of introduced honeybees, we warn that certain orchids may suffer from pollen depletion by these invaders, especially in altered habitats with compromised pollination communities.
Topics: Animals; Bees; Pollination; Orchidaceae; Pollen; Introduced Species; Ecosystem; Male; Reproduction; Australia; Female
PubMed: 38890342
DOI: 10.1038/s41598-024-64218-x -
Proceedings. Biological Sciences Jun 2024Extreme heat poses a major threat to plants and pollinators, yet the indirect consequences of heat stress are not well understood, particularly for native solitary bees....
Extreme heat poses a major threat to plants and pollinators, yet the indirect consequences of heat stress are not well understood, particularly for native solitary bees. To determine how brief exposure of extreme heat to flowering plants affects bee behaviour, fecundity, development and survival we conducted a no-choice field cage experiment in which were provided blueberry (), phacelia () and white clover () that had been previously exposed to either extreme heat (37.5°C) or normal temperatures (25°C) for 4 h during early bloom. Despite a similar number of open flowers and floral visitation frequency between the two treatments, female bees provided with heat-stressed plants laid approximately 70% fewer eggs than females provided with non-stressed plants. Their progeny received similar quantities of pollen provisions between the two treatments, yet larvae consuming pollen from heat-stressed plants had significantly lower survival as larvae and adults. We also observed trends for delayed emergence and reduced adult longevity when larvae consumed heat-stressed pollen. This study is the first to document how short, field-realistic bursts of extreme heat exposure to flowering host plants can indirectly affect bee pollinators and their offspring, with important implications for crop pollination and native bee populations.
Topics: Animals; Bees; Fertility; Pollination; Female; Extreme Heat; Hot Temperature; Longevity; Pollen
PubMed: 38889783
DOI: 10.1098/rspb.2024.0714 -
Horticulture Research Jun 2024The economically significant genus includes fruit and nut crops that have been domesticated for shared and specific agronomic traits; however, the genomic signals of...
The economically significant genus includes fruit and nut crops that have been domesticated for shared and specific agronomic traits; however, the genomic signals of convergent and divergent selection have not been elucidated. In this study, we aimed to detect genomic signatures of convergent and divergent selection by conducting comparative population genomic analyses of the apricot-peach-plum-mei (APPM) complex, utilizing a haplotype-resolved telomere-to-telomere (T2T) genome assembly and population resequencing data. The haplotype-resolved T2T reference genome for the plum cultivar was assembled through HiFi and Hi-C reads, resulting in two haplotypes 251.25 and 251.29 Mb in size, respectively. Comparative genomics reveals a chromosomal translocation of ~1.17 Mb in the apricot genomes compared with peach, plum, and mei. Notably, the translocation involves the locus, significantly impacting titratable acidity (TA), pH, and sugar content. Population genetic analysis detected substantial gene flow between plum and apricot, with introgression regions enriched in post-embryonic development and pollen germination processes. Comparative population genetic analyses revealed convergent selection for stress tolerance, flower development, and fruit ripening, along with divergent selection shaping specific crop, such as somatic embryogenesis in plum, pollen germination in mei, and hormone regulation in peach. Notably, selective sweeps on chromosome 7 coincide with a chromosomal collinearity from the comparative genomics, impacting key fruit-softening genes such as , regulated by and . Overall, this study provides insights into the genetic diversity, evolutionary history, and domestication of the APPM complex, offering valuable implications for genetic studies and breeding programs of crops.
PubMed: 38883333
DOI: 10.1093/hr/uhae109 -
Environmental Science: Atmospheres Jun 2024Microplastic particles in the atmosphere are regularly detected in urban areas as well as in very remote locations. Yet the sources, chemical transformation, transport,...
Microplastic particles in the atmosphere are regularly detected in urban areas as well as in very remote locations. Yet the sources, chemical transformation, transport, and abundance of airborne microplastics still remain largely unexplained. Therefore, their impact on health, weather and climate related processes lacks comprehensive understanding. Single particle detection presents a substantial challenge due to its time-consuming process and is conducted solely offline. To get more information about the distribution, fluxes and sources of microplastics in the atmosphere, a reliable and fast online measurement technique is of utmost importance. Here we demonstrate the use of the autofluorescence of microplastic particles for their online detection with a high sensitivity towards different widely used polymers. We deploy online, single particle fluorescence spectroscopy with a Wideband Integrated Bioaerosol Sensor WIBS 5/NEO (Droplet Measurement Technologies, USA), which enables single particle fluorescence measurements at two excitation wavelengths (280 nm and 370 nm) and in two emission windows (310-400 nm and 420-650 nm). We investigated shredded (<100 μm) everyday plastic products (drinking bottles and yogurt cups) and pure powders of polyethylene terephthalate (PET), polyethylene and polypropylene. For the broad range of typical plastic products analyzed, we detected fluorescence on a single particle level using the WIBS. The online detection can identify particles smaller than 2 μm. In the case of microplastic particles from a PET bottle, 1.2 μm sized particles can be detected with 95% efficiency. Comparison with biological aerosols reveals that microplastics can be distinguished from two abundant pollen species and investigation of the complete fluorescence excitation emission maps of all samples shows that online identification of microplastics might be possible with fluorescence techniques if multiple channels are available.
PubMed: 38883229
DOI: 10.1039/d4ea00010b -
Ecology and Evolution Jun 2024During past glacial periods, the land cover of Northern Eurasia and North America repeatedly shifted between open steppe tundra and boreal/temperate forest. Tracking...
During past glacial periods, the land cover of Northern Eurasia and North America repeatedly shifted between open steppe tundra and boreal/temperate forest. Tracking these changes and estimating the coverage of open versus forested vegetation in past glacial and interglacial landscapes is notoriously difficult because the characteristic dwarf birches of the tundra and the tree birches of the boreal and temperate forests produce similar pollen grains that are difficult to distinguish in the pollen record. One objective approach to separating dwarf birch pollen from tree birch pollen is to use grain size statistics. However, the required grain size measurements are time-consuming and, therefore, rarely produced. Here, we present an approach to automatic size measurement based on image recognition with convolutional neural networks and machine learning. It includes three main steps. First, the TOFSI algorithm is applied to detect and classify pollen, including birch pollen, in lake sediment samples. Second, a Resnet-18 neural network is applied to select the birch pollen suitable for measurement. Third, semantic segmentation is applied to detect the outline and the area and mean width of each detected birch pollen grain. Test applications with two pollen records from Northern Germany, one covering the Lateglacial-Early Holocene transition and the other covering the Mid to Late Pleistocene transition, show that the new technical approach is well suited to measure the area and mean width of birch pollen rapidly (>1000 per hour) and with high accuracy. Our new network-based tool facilitates more regular size measurements of birch pollen. Expanded analysis of modern birch pollen will help to better understand size variations in birch pollen between birch species and in response to environmental factors as well as differential sample preparation. Analysis of fossil samples will allow better quantification of dwarf birch versus tree birch in past environments.
PubMed: 38882530
DOI: 10.1002/ece3.11510 -
PhytoKeys 2024This study describes X.Q. Song, B.N. Song & Biao Yang, , a new species collected from the Yingjing area of the Giant Panda National Park. This new species is...
This study describes X.Q. Song, B.N. Song & Biao Yang, , a new species collected from the Yingjing area of the Giant Panda National Park. This new species is distributed at an altitude of 1400-2100 m, with a plant height of 30-130 cm. The flowers are purple-red or light purple red, with 3-9 flowers on each inflorescence and the dorsal auricle of the lateral united petals is thread-like and about 2 cm long, differing significantly from other species of . Furthermore, molecular data, as well as micro-morphological evidence under SEM (of pollens), also support the establishment of the new species.
PubMed: 38881763
DOI: 10.3897/phytokeys.242.119702 -
Frontiers in Microbiology 2024Invasive pests may disturb and destructively reformat the local ecosystem. The small hive beetle (SHB), , originated in Africa and has expanded to America, Australia,...
Invasive pests may disturb and destructively reformat the local ecosystem. The small hive beetle (SHB), , originated in Africa and has expanded to America, Australia, Europe, and Asia. A key factor facilitating its fast global expansion is its ability to subsist on diverse food inside and outside honey bee colonies. SHBs feed on various plant fruits and exudates in the environment while searching for bee hives. After sneaking into a bee hive, they switch their diet to honey, pollen, and bee larvae. How SHBs survive on such a broad range of food remains unclear. In this study, we simulated the outside and within hive stages by providing banana and hive resources and quantified the SHB associated microbes adjusted by the diet. We found that SHBs fed on bananas were colonized by microbes coding more carbohydrate-active enzymes and a higher alpha diversity than communities from SHBs feeding on hive products or those collected directly from bee hives. SHBs fed on bananas and those collected from the hive showed high symbiont variance, indicated by the beta diversity. Surprisingly, we found the honey bee core symbiont in the guts of SHBs collected in bee hives. To determine the role of in SHB biology, we inoculated SHBs with a genetically tagged culture of showing that this symbiont is a likely transient of SHBs. In contrast, the fungus is the primary commensal of SHBs. Diet-based microbiome shifts are likely to play a key role in the spread and success of SHBs.
PubMed: 38881661
DOI: 10.3389/fmicb.2024.1387248 -
Genomics Jun 2024Cynanchum thesioides, a xerophytic species utilized both as a medicinal herb and a food source, plays a significant role in arid and desert ecosystem management. Its...
Cynanchum thesioides, a xerophytic species utilized both as a medicinal herb and a food source, plays a significant role in arid and desert ecosystem management. Its inflorescence is an umbellate cyme, each carrying nearly a thousand flowers; however, its fruiting rate remains remarkably low. The normal development of the anther is a necessary prerequisite for plants to produce seeds. However, our understanding of the anther development process in Cynanchum thesioides remains limited. To better understand the pollen development process in Cynanchum thesioides, the stages of pollen development were determined through paraffin sectioning, and observations were made on the distribution characteristics of polysaccharides and lipid droplets in the pollen development of Cynanchum thesioides using Periodic Acid-Schiff stain (PAS) and 0.5% Sudan Black B tissue staining. Concurrently, the gene expression patterns and metabolite profiles were delineated across various developmental stages of Cynanchum thesioides anthers (T1: microspore stage, T2: tetrad stage, T3: mononuclear stage, and T4: maturation stage). The findings revealed that Cynanchum thesioides pollen is in an aggregate form. Polysaccharides gradually accumulate during maturation and lipid droplets form a surrounding membrane, thereby preventing pollen dispersion. Furthermore, transcriptomic and metabolomic analyses across distinct developmental phases uncovered a plethora of differentially expressed genes and metabolites associated with the flavonoid biosynthesis pathway. Flavonoid levels exhibited dynamic changes concurrent with anther development, aligning with the gene regulatory patterns of the corresponding biosynthetic pathways. The study identified 63 differentially accumulated flavonoid compounds and 21 differentially expressed genes associated with flavonoid biosynthesis. Weighted gene co-expression network analysis revealed six MYB and ten bHLH transcription factors as key candidates involved in flavonoid biosynthesis, with CtbHLH (Cluster-6587.1050) and CtMYB (Cluster-6587.31743) specifically regulating structural genes within the pathway. These findings underscore the pivotal role of flavonoid biosynthesis in anther development of Cynanchum thesioides. In conclusion, this research offers a comprehensive insight into the anther development process in Cynanchum thesioides.
PubMed: 38878835
DOI: 10.1016/j.ygeno.2024.110884