Browsing by Subject "11831 Plant biology"

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  • Paterlini, Andrea; Dorussen, Delfi; Fichtner, Franziska; van Rongen, Martin; Delacruz, Ruth; Vojnovic, Ana; Helariutta, Yrjö; Leyser, Ottoline (2021)
  • Lizarazo, Clara; Lampi, Anna-Maija; Mäkelä, Pirjo (2021)
    Caraway seeds contain between 0.5-7% essential oil, rich in monoterpenes that have a characteristic aroma and chemical properties. Caraway oil has several bioactive compounds that are of industrial importance, particularly for pharmaceutical and health care products. Carvone and limonene are the main terpenes present in caraway oil, which along with some unique fatty acids (i.e. petroselinic acid) determine caraway (Carum carvi L.) oil quality. Both terpenes are important raw materials for industrial applications and their concentration influences the price of caraway seed and oil, hence there is need for identifying management practices that may increase the concentration of these and other bioactive compounds to improve caraway seed oil quality. A field experiment with five treatments: a control and a series of foliar-applied micronutrients (either Cu, Mg, Mn or Zn was done to identify their potential to enhance caraway oil quality. Solid-phase microextraction and gas chromatography with a flame ionization detector were used to characterize oil quality. Our results indicate that while the micronutrient treatments have a significant effect on essential oil composition, both in carvone and limonene, such an effect was not found on all fatty acids but only in two of them-palmitoleic and vaccenic acid-, which were highest after the Mn treatment. Overall, the carvone content of the seeds decreased the least between years following Mn treatment. Mn treatment also caused an increase in limonene in the second year in contrast to the trend for all other treatments. The Mn foliar spray needs to be studied further to elucidate whether it could have a consistent positive effect on caraway oil seed quality upon adjusting dosage and spraying time.
  • Väre, Henry (2021)
    Mårten Magnus Wilhelm Brenner (1843–1930) was a non-professional Finnish botanist who published 220 articles or notes. Brenner worked on East Fennoscandian vascular plants (the territory of present-day Finland and adjacent Russia). He validly published ca. 833 new taxa, especially in genus Hieracium (including Pilosella), and introduced 56 names as nomina nuda. Brenner had no concept of type specimens and therefore all his plant taxa need typification, and 151 of those are lectotypified here. In this paper, nomina nuda and the taxa whose type material was not found are also listed, except those of the apomictic genera Hieracium and Taraxacum. Many of Brenner’s new taxa are forms and varieties, generally not recognised nowadays. Many of his taxa were based on single or few specimens and therefore were characterised by local distributions, whereas some include ample original material. Finnish botanists generally ignored Brenner’s contributions to taxonomy. However, 11 species of Hieracium, 20 of Taraxacum and Euphrasia stricta var. tenuis (Brenner) Jalas are currently recognised, and recently also E. wettsteinii var. botniensium (Brenner) Piirainen. Together Brenner’s type collection treated here consists of 254 sheets (Hieracium and Taraxacum excluded), deposited at the Botanical Museum (H), Finnish Museum of Natural History, University of Helsinki, Finland.
  • Nunes, Matheus; Both, Sabine; Bongalov, Boris; Brelsford, Craig; Khoury, Sacha; Burslem, David; Philipson, Christopher; Majalap, Noreen; Riutta, Terhi; Coomes, David; Cutler, Mark (2019)
    El Nino events generate periods of relatively low precipitation, low cloud cover and high temperature over the rainforests of Southeast Asia, but their impact on tree physiology remains poorly understood. Here we use remote sensing and functional trait approaches-commonly used to understand plant acclimation to environmental fluctuations-to evaluate rainforest responses to an El Nino event at a site in northern Borneo. Spaceborne measurements (i.e. normalised difference vegetation index calculated from Moderate Resolution Imaging Spectroradiometer data) show the rainforest canopy greened throughout 2015, coinciding with a strengthening of the El Nino event in Sabah, Malaysia, then lost greenness in early 2016, when the El Nino was at its peak. Leaf chemical and structural traits measured for mature leaves of 65 species (104 branches from 99 tree canopies), during and after this El Nino event revealed that chlorophyll and carotenoid concentrations were 35% higher in mid 2015 than in mid 2016. Foliar concentrations of the nutrients N, P, K and Mg did not vary, suggesting the mineralisation and transportation processes were unaffected by the El Nino event. Leaves contained more phenolics, tannins and cellulose but less Ca and lignin during the El Nino event, with concentration shifts varying strongly among species. These changes in functional traits were also apparent in hyperspectral reflectance data collected using a field spectrometer, particularly in the shortwave infrared region. Leaf-level acclimation and leaf turnover could have driven the trait changes observed. We argue that trees were not water limited in the initial phase of the El Nino event, and responded by flushing new leaves, seen in the canopy greening trend and higher pigment concentrations (associated with young leaves); we argue that high evaporative demand and depleted soil water eventually caused leaves to drop in 2016. However, further studies are needed to confirm these ideas. Time-series of vegetation dynamics obtained from space can only be understood if changes in functional traits, as well as the quantity of leaves in canopies, are monitored on the ground.
  • Kapp, Karmen; Püssa, Tõnu; Orav, Anne; Roasto, Mati; Raal, Ain; Vuorela, Pia; Vuorela, Heikki; Tammela, Päivi (2020)
    Mentha spp. are used in the food and pharmaceutical industry; the plants are characterized by natural interspecies hybridization. In this study, knowledge of the chemical composition of Mentha spp. was broadened by focusing on plants grown in a geographically small region of Estonia. The antibacterial activity of Mentha spp. essential oils and water extracts was evaluated. Polyphenolic water extracts of M. x villosa Huds., M. x suaveolens Ehrh., and M. x gracilis Sole were tested for the first time on Escberichia coli and Staphylococcus aura's. Leaves of cultivated and wild-grown plants (n = 33) were collected. The microdistilled essential oil composition reflected the diversity within the genus Mentha. Determined by gas chromatography-mass spectrometry (MS), major compounds were cis-piperitone oxide, carvone, linalool, menthol, and menthofuran. Based on high-performance liquid chromatographyultraviolet-MS/MS analyses of the water extracts, no species-specific polyphenolic compounds could be proposed. Abundant polyphenols were rosmarinic acid, salvianolic acid B, and eriocitrin. Essential oils exhibited antibacterial activity on E. coli and S. aureus by the broth dilution method. Water extracts showed activity only against S. aureus. This study supports the use of Mentha spp. as health-promoting ingredients in food. However, further studies are still needed to widen the knowledge of the chemical composition of these plants.
  • Fewer, David P.; Jokela, Jouni; Heinila, Lassi; Aesoy, Reidun; Sivonen, Kaarina; Galica, Tomas; Hrouzek, Pavel; Herfindal, Lars (2021)
    Cyanobacteria produce a variety of chemically diverse cyclic lipopeptides with potent antifungal activities. These cyclic lipopeptides have an amphipathic structure comprised of a polar peptide cycle and hydrophobic fatty acid side chain. Many have antibiotic activity against a range of human and plant fungal pathogens. This review article aims to summarize the present knowledge on the chemical diversity and cellular effects of cyanobacterial cyclic lipopeptides that display antifungal activity. Cyclic antifungal lipopeptides from cyanobacteria commonly fall into four structural classes; hassallidins, puwainaphycins, laxaphycins, and anabaenolysins. Many of these antifungal cyclic lipopeptides act through cholesterol and ergosterol-dependent disruption of membranes. In many cases, the cyclic lipopeptides also exert cytotoxicity in human cells, and a more extensive examination of their biological activity and structure-activity relationship is warranted. The hassallidin, puwainaphycin, laxaphycin, and anabaenolysin structural classes are unified through shared complex biosynthetic pathways that encode a variety of unusual lipoinitiation mechanisms and branched biosynthesis that promote their chemical diversity. However, the biosynthetic origins of some cyanobacterial cyclic lipopeptides and the mechanisms, which drive their structural diversification in general, remain poorly understood. The strong functional convergence of differently organized chemical structures suggests that the production of lipopeptide confers benefits for their producer. Whether these benefits originate from their antifungal activity or some other physiological function remains to be answered in the future. However, it is clear that cyanobacteria encode a wealth of new cyclic lipopeptides with novel biotechnological and therapeutic applications.
  • Abdullah,; Henriquez, Claudia L.; Mehmood, Furrukh; Hayat, Aamir; Sammad, Abdul; Waseem, Shahid; Waheed, Mohammad Tahir; Matthews, Peter J.; Croat, Thomas B; Poczai, Péter; Ahmed, Ibrar (2021)
    Chloroplast (cp) genomes are considered important for the study of lineage-specific molecular evolution, population genetics, and phylogenetics. Our aim here was to elucidate the molecular evolution in cp genomes of species in the Dracunculus clade (Aroideae, Araceae). We report de novo assembled cp genomes for eight species from eight genera and also retrieved cp genomes of four species from the National Center for Biotechnology Information (NCBI). The cp genomes varied in size from 162,424 bp to 176,835 bp. Large Single Copy (LSC) region ranged in size from 87,141 bp to 95,475 bp; Small Single Copy (SSC) from 14,338 bp to 23,981 bp; and Inverted Repeats (IRa and IRb) from 25,131 bp to 32,708 bp. The expansion in inverted repeats led to duplication of ycf1 genes in four species. The genera showed high similarity in gene content and yielded 113 unique genes (79 protein-coding, 4 rRNA, and 30 tRNA genes). Codon usage, amino acid frequency, RNA editing sites, microsatellites repeats, transition and transversion substitutions, and synonymous and non-synonymous substitutions were also similar across the clade. A previous study reported deletion of ycf1, accD, psbE, trnL-CAA, and trnG-GCC genes in four Amorphophallus species. Our study supports conservative structure of cp genomes in the Dracunculus clade including Amorphophallus species and does not support gene deletion mentioned above. We also report suitable polymorphic loci based on comparative analyses of Dracunculus clade species, which could be useful for phylogenetic inference. Overall, the current study broad our knowledge about the molecular evolution of chloroplast genome in aroids.
  • Rabanus-Wallace, M. Timothy; Hackauf, Bernd; Mascher, Martin; Lux, Thomas; Wicker, Thomas; Gundlach, Heidrun; Baez, Mariana; Houben, Andreas; Mayer, Klaus F. X.; Guo, Liangliang; Poland, Jesse; Pozniak, Curtis J.; Walkowiak, Sean; Melonek, Joanna; Praz, Coraline R.; Schreiber, Mona; Budak, Hikmet; Heuberger, Matthias; Steuernagel, Burkhard; Wulff, Brande; Boerner, Andreas; Byrns, Brook; Cizkova, Jana; Fowler, D. Brian; Fritz, Allan; Himmelbach, Axel; Kaithakottil, Gemy; Keilwagen, Jens; Keller, Beat; Konkin, David; Larsen, Jamie; Li, Qiang; Myskow, Beata; Padmarasu, Sudharsan; Rawat, Nidhi; Sesiz, Ugur; Biyiklioglu-Kaya, Sezgi; Sharpe, Andy; Simkova, Hana; Small, Ian; Swarbreck, David; Toegelova, Helena; Tsvetkova, Natalia; Voylokov, Anatoly V.; Vrana, Jan; Bauer, Eva; Bolibok-Bragoszewska, Hanna; Dolezel, Jaroslav; Hall, Anthony; Jia, Jizeng; Korzun, Viktor; Laroche, Andre; Ma, Xue-Feng; Ordon, Frank; Ozkan, Hakan; Rakoczy-Trojanowska, Monika; Scholz, Uwe; Schulman, Alan H.; Siekmann, Dorthe; Stojalowski, Stefan; Tiwari, Vijay K.; Spannagl, Manuel; Stein, Nils (2021)
    Rye (Secale cereale L.) is an exceptionally climate-resilient cereal crop, used extensively to produce improved wheat varieties via introgressive hybridization and possessing the entire repertoire of genes necessary to enable hybrid breeding. Rye is allogamous and only recently domesticated, thus giving cultivated ryes access to a diverse and exploitable wild gene pool. To further enhance the agronomic potential of rye, we produced a chromosome-scale annotated assembly of the 7.9-gigabase rye genome and extensively validated its quality by using a suite of molecular genetic resources. We demonstrate applications of this resource with a broad range of investigations. We present findings on cultivated rye's incomplete genetic isolation from wild relatives, mechanisms of genome structural evolution, pathogen resistance, low-temperature tolerance, fertility control systems for hybrid breeding and the yield benefits of rye-wheat introgressions.
  • Gawronski, Piotr; Burdiak, Pawel; Scharff, Lars B.; Mielecki, Jakub; Gorecka, Magdalena; Zaborowska, Magdalena; Leister, Dario; Waszczak, Cezary; Karpinski, Stanislaw (2021)
    Chloroplast-to-nucleus retrograde signaling is essential for cell function, acclimation to fluctuating environmental conditions, plant growth and development. The vast majority of chloroplast proteins are nuclear-encoded, and must be imported into the organelle after synthesis in the cytoplasm. This import is essential for the development of fully functional chloroplasts. On the other hand, functional chloroplasts act as sensors of environmental changes and can trigger acclimatory responses that influence nuclear gene expression. Signaling via mobile transcription factors (TFs) has been recently recognized as a way of communication between organelles and the nucleus. In this study, we performed a targeted reverse genetic screen to identify dual-localized TFs involved in chloroplast retrograde signaling during stress responses. We found that CHLOROPLAST IMPORT APPARATUS 2 (CIA2) has a functional plastid transit peptide, and can be located both in chloroplasts and the nucleus. Further, we found that CIA2, along with its homolog CIA2-like (CIL) are involved in the regulation of Arabidopsis responses to UV-AB, high light and heat shock. Finally, our results suggest that both CIA2 and CIL are crucial for chloroplast translation. Our results contribute to a deeper understanding of signaling events in the chloroplast-nucleus cross-talk.
  • Marjakangas, Emma-Liina; Ovaskainen, Otso; Abrego, Nerea; Grøtan, Vidar; de Oliveira, Alexandre A.; Prado, Paulo I.; de Lima, Renato A. F. (2021)
    Species co-occurrences in local communities can arise independent or dependent on species' niches. However, the role of niche-dependent processes has not been thoroughly deciphered when generalized to biogeographical scales, probably due to combined shortcomings of data and methodology. Here, we explored the influence of environmental filtering and limiting similarity, as well as biogeographical processes that relate to the assembly of species' communities and co-occurrences. We modelled jointly the occurrences and co-occurrences of 1016 tropical tree species with abundance data from inventories of 574 localities in eastern South America. We estimated species co-occurrences as raw and residual associations with models that excluded and included the environmental effects on the species' co-occurrences, respectively. Raw associations indicate co-occurrence of species, whereas residual associations indicate co-occurrence of species after accounting for shared responses to environment. Generally, the influence of environmental filtering exceeded that of limiting similarity in shaping species' co-occurrences. The number of raw associations was generally higher than that of the residual associations due to the shared responses of tree species to the environmental covariates. Contrary to what was expected from assuming limiting similarity, phylogenetic relatedness or functional similarity did not limit tree co-occurrences. The proportions of positive and negative residual associations varied greatly across the study area, and we found a significant tendency of some biogeographical regions having higher proportions of negative associations between them, suggesting that large-scale biogeographical processes limit the establishment of trees and consequently their co-occurrences.
  • Nygaard, Malene; Kemppainen, Petri; Speed, James D. M.; Elven, Reidar; Flatberg, Kjell Ivar; Galten, Leif P.; Yousefi, Narjes; Solstad, Heidi; Bendiksby, Mika (2021)
    Carex section Ceratocystis (Cyperaceae) is a group of recently evolved plant species, in which hybridization is frequent, introgression is documented, taxonomy is complex, and morphological boundaries are vague. Within this section, a unified taxonomic treatment of the Carex jemtlandica-Carex lepidocarpa species complex does not exist, and Norway may currently be the sole country accepting species rank for both. Carex jemtlandica is mainly confined to Fennoscandia and is thus a Fennoscandian conservation responsibility. This motivated us to test the principal hypothesis that both C. jemtlandica and C. lepidocarpa represent evolutionary significant units, and that both deserve their current recognition at species level. We investigated their evolutionary distinctiveness in Norway, using restriction site-associated DNA sequencing and ecological niche modeling. Our genomic results reveal two genetic clusters, largely corresponding to C. jemtlandica and C. lepidocarpa that also remain distinct in sympatry, despite clear indications of ongoing hybridization and introgression. The ecological niche modeling suggests that they occupy different environmental niches. Jointly, our results clearly show that C. jemtlandica and C. lepidocarpa represent separately evolving entities that should qualify recognition as evolutionary significant units. Given the high level of introgression compared to other hybridizing species pairs in Carex we recommend treating C. jemtlandica as a subspecies of C. lepidocarpa.
  • Rehman, Umar; Sultana, Nighat; Abdullah,; Jamal, Abbas; Muzaffar, Maryam; Poczai, Péter (2021)
    Family Phyllanthaceae belongs to the eudicot order Malpighiales, and its species are herbs, shrubs, and trees that are mostly distributed in tropical regions. Here, we elucidate the molecular evolution of the chloroplast genome in Phyllanthaceae and identify the polymorphic loci for phylogenetic inference. We de novo assembled the chloroplast genomes of three Phyllanthaceae species, i.e., Phyllanthus emblica, Flueggea virosa, and Leptopus cordifolius, and compared them with six other previously reported genomes. All species comprised two inverted repeat regions (size range 23,921–27,128 bp) that separated large single-copy (83,627–89,932 bp) and small single-copy (17,424–19,441 bp) regions. Chloroplast genomes contained 111–112 unique genes, including 77–78 protein-coding, 30 tRNAs, and 4 rRNAs. The deletion/pseudogenization of rps16 genes was found in only two species. High variability was seen in the number of oligonucleotide repeats, while guanine-cytosine contents, codon usage, amino acid frequency, simple sequence repeats, synonymous and non-synonymous substitutions, and transition and transversion substitutions were similar. The transition substitutions were higher in coding sequences than in non-coding sequences. Phylogenetic analysis revealed the polyphyletic nature of the genus Phyllanthus. The polymorphic proteincoding genes, including rpl22, ycf1, matK, ndhF, and rps15, were also determined, which may be helpful for reconstructing the high-resolution phylogenetic tree of the family Phyllanthaceae. Overall, the study provides insight into the chloroplast genome evolution in Phyllanthaceae.
  • Wu, Jiayao; Choi, Jaeyoung; Asiegbu, Fred O.; Lee, Yong-Hwan (2020)
    Abstract Laccases (EC, a group of multi-copper oxidases (MCOs), play multiple biological functions and widely exist in many species. Fungal laccases have been extensively studied for their industrial applications, however, there was no database specially focused on fungal laccases. To provide a comparative genomics platform for fungal laccases, we have developed a comparative genomics platform for laccases and MCOs ( Based on protein domain profiles of characterized sequences, 3,571 laccases were predicted from 690 genomes including 253 fungi. The number of putative laccases and their properties exhibited dynamic distribution across the taxonomy. A total of 505 laccases from 68 genomes were selected and subjected to phylogenetic analysis. As a result, four clades comprised of nine subclades were phylogenetically grouped by their putative functions and analyzed at the sequence level. Our work would provide a workbench for putative laccases mainly focused on the fungal kingdom as well as a new perspective in the identification and classification of putative laccases and MCOs.
  • Abdullah,; Mehmood, Furrukh; Heidari, Parviz; Ahmed, Ibrar; Poczai, Péter (2021)
    The genus Blumea (Asteroideae, Asteraceae) comprises about 100 species, including herbs, shrubs, and small trees. Previous studies have been unable to resolve taxonomic issues and the phylogeny of the genus Blumea due to the low polymorphism of molecular markers. Therefore, suitable polymorphic regions need to be identified. Here, we de novo assembled plastomes of the three Blumea species B. oxyodonta, B. tenella, and B. balsamifera and compared them with 25 other species of Asteroideae after correction of annotations. These species have quadripartite plastomes with similar gene content and genome organization comprising 113 genes, including 80 protein-coding, 29 transfer RNA, and 4 ribosomal RNA genes. The contraction and expansion of inverted repeats also show high similarities among the species. The comparative analysis of codon usage, amino acid frequency, microsatellite repeats, oligonucleotide repeats, and transition and transversion substitutions has revealed high resemblance among the newly assembled species of Blumea. We identified 10 highly polymorphic regions with nucleotide diversity above 0.02, including rps16-trnQ, ycf1, ndhF-rpl32, rps15, petN-psbM, and rpl32-trnL, and they may be suitable for the development of robust, authentic, and cost-effective markers for bar coding and inference of the phylogeny of the genus Blumea. Among these highly polymorphic regions, five regions also co-occurred with oligonucleotide repeats and support use of repeats as a proxy for the identification of polymorphic loci. The phylogenetic analysis revealed a close relationship between Blumea and Pluchea within the tribe Inuleae. Our study supports a sister relationship between “Astereae and Anthemideae,” while Gnaphalieae roots these two tribes, whereas in a previous study a sister relationship was reported between “Senecioneae and Anthemideae” and “Astereae and Gnaphalieae” using nuclear genome sequences. The conflicting phylogenetic signals observed at the tribal level between chloroplast and nuclear genome data require further investigation.
  • Abdullah,; Henriquez, Claudia L.; Mehmood, Furrukh; Shahzadi, Iram; Ali, Zain; Waheed, Mohammad Tahir; Croat, Thomas B; Poczai, Péter; Ahmed, Ibrar (2020)
    The chloroplast genome provides insight into the evolution of plant species. We de novo assembled and annotated chloroplast genomes of four genera representing three subfamilies of Araceae: Lasia spinosa (Lasioideae), Stylochaeton bogneri, Zamioculcas zamiifolia (Zamioculcadoideae), and Orontium aquaticum (Orontioideae), and performed comparative genomics using these chloroplast genomes. The sizes of the chloroplast genomes ranged from 163,770 bp to 169,982 bp. These genomes comprise 113 unique genes, including 79 protein-coding, 4 rRNA, and 30 tRNA genes. Among these genes, 17–18 genes are duplicated in the inverted repeat (IR) regions, comprising 6–7 protein-coding (including trans-splicing gene rps12), 4 rRNA, and 7 tRNA genes. The total number of genes ranged between 130 and 131. The infA gene was found to be a pseudogene in all four genomes reported here. These genomes exhibited high similarities in codon usage, amino acid frequency, RNA editing sites, and microsatellites. The oligonucleotide repeats and junctions JSB (IRb/SSC) and JSA (SSC/IRa) were highly variable among the genomes. The patterns of IR contraction and expansion were shown to be homoplasious, and therefore unsuitable for phylogenetic analyses. Signatures of positive selection were seen in three genes in S. bogneri, including ycf2, clpP, and rpl36. This study is a valuable addition to the evolutionary history of chloroplast genome structure in Araceae.
  • Kaasalainen, Ulla Susanna; Tuovinen, Veera; Mwachala, Geoffrey; Pellikka, Petri; Rikkinen, Jouko Kalevi (2021)
    Interactions within lichen communities include, in addition to close mutualistic associations between the main partners of specific lichen symbioses, also more elusive relationships between members of a wider symbiotic community. Here, we analyze association patterns of cyanolichen symbionts in the tropical montane forests of Taita Hills, southern Kenya, which is part of the Eastern Afromontane biodiversity hotspot. The cyanolichen specimens analyzed represent 74 mycobiont taxa within the order Peltigerales (Ascomycota), associating with 115 different variants of the photobionts genus Nostoc (Cyanobacteria). Our analysis demonstrates wide sharing of photobionts and reveals the presence of several photobiont-mediated lichen guilds. Over half of all mycobionts share photobionts with other fungal species, often from different genera or even families, while some others are strict specialists and exclusively associate with a single photobiont variant. The most extensive symbiont network involves 24 different fungal species from five genera associating with 38 Nostoc photobionts. The Nostoc photobionts belong to two main groups, the Nephroma-type Nostoc and the Collema/Peltigera-type Nostoc, and nearly all mycobionts associate only with variants of one group. Among the mycobionts, species that produce cephalodia and those without symbiotic propagules tend to be most promiscuous in photobiont choice. The extent of photobiont sharing and the structure of interaction networks differ dramatically between the two major photobiont-mediated guilds, being both more prevalent and nested among Nephroma guild fungi and more compartmentalized among Peltigera guild fungi. This presumably reflects differences in the ecological characteristics and/or requirements of the two main groups of photobionts. The same two groups of Nostoc have previously been identified from many lichens in various lichen-rich ecosystems in different parts of the world, indicating that photobiont sharing between fungal species is an integral part of lichen ecology globally. In many cases, symbiotically dispersing lichens can facilitate the dispersal of sexually reproducing species, promoting establishment and adaptation into new and marginal habitats and thus driving evolutionary diversification.
  • Paterlini, Andrea; Belevich, Ilya; Jokitalo, Eija; Helariutta, Yrjö (2020)
    Plasmodesmata are small channels that connect plant cells. While recent technological advances have facilitated analysis of the ultrastructure of these channels, there are limitations to efficiently addressing their presence over an entire cellular interface. Here, we highlight the value of serial block electron microscopy for this purpose. We developed a computational pipeline to study plasmodesmata distributions and detect the presence/absence of plasmodesmata clusters, or pit fields, at the phloem unloading interfaces of Arabidopsis (Arabidopsis thaliana) roots. Pit fields were visualized and quantified. As the wall environment of plasmodesmata is highly specialized, we also designed a tool to extract the thickness of the extracellular matrix at and outside of plasmodesmata positions. We detected and quantified clear wall thinning around plasmodesmata with differences between genotypes, including the recently published plm-2 sphingolipid mutant. Our tools open avenues for quantitative approaches in the analysis of symplastic trafficking.
  • Wang, Fang; Robson, T Matthew; Casal, Jorge J; Aphalo, Pedro J. (2020)
    The UV-A/blue photoreceptors phototropins and cryptochromes are both known to contribute to stomatal opening (∆gs) in blue light. However, their relative contributions to maintenance of gs in blue light through the whole photoperiod remains unknown. To elucidate this question, Arabidopsis phot1 phot2 and cry1 cry2 mutants (MTs) and their respective wild types (WTs) were irradiated with 200 μmol m-2 s-1 of blue-, green- or red-light (BL, GL or RL) throughout a 11-hour photoperiod. Stomatal conductance (gs) was higher under BL, than under RL or GL. Under RL, gs was not affected by either of the photoreceptor mutations, but under GL gs was slightly lower in cry1 cry2 than its WT. Under BL, the presence of phototropins was essential for rapid stomatal opening at the beginning of the photoperiod, while maximal stomatal opening beyond 3 h of irradiation required both phototropins and cryptochromes. Time courses of whole-plant net carbon assimilation rate (Anet) and the effective quantum yield of photosystem II photochemistry (ΦPSII) were consistent with an Anet-independent contribution of BL on gs both in phot1 phot2 and cry1 cry2 mutants. The changing roles of phototropins and cryptochromes through the day may allow more flexible coordination between gs and Anet.
  • Enroth, Johannes; Shevock, James R. (2021)
    Three species previously thought to be Chinese endemics from the easternmost Himalayas are reported from Bhutan: Shevockia inunctocarpa Enroth & M.C. Ji and Taiwanobryum yunnanense (Enroth) Enroth comb. nov. of the Neckeraceae, and Calyptothecium acostatum J.X. Luo of the Pterobryaceae. The latter, originally described from Xizang, is also reported from Yunnan, China. Additionally, Noguchiodendron sphaerocarpum (Nog.) Ninh & Pócs is reported for the second time (since 1971) from Bhutan.
  • Hytönen, Timo; Kurokura, Takeshi (2020)
    Strawberry flowering physiology has engaged the interest of researchers for almost a century after the initial reports demonstrating the photoperiodic control of flowering and N egetative reproduction through stolons called runners. Most strawberries possess a seasonal flowering habit with flower initiation occurring under short days in autumn and flowering during the following spring. Also perpetual flowering genotypes are known in diploid woodland strawberry (Fragaria vesca L.) and octoploid garden strawberry (F. x ananassa Duch.), and recent research have shown that this trait has evolved independently in different species. Studies in the perpetual flowering mutant of woodland strawberry led to the identification of TERMINAL FLOWER1 (FvTFL1) as a major floral repressor causing the seasonal flowering habit in this species and demonstrated that recessive mutation in this gene leads to perpetual flowering. This breakthrough opened an avenue for molecular understanding on the control of flowering by different environmental signals. Different loci control perpetual flowering in garden strawberry including one dominant major locus and additional environmentally regulated epistatic loci. The major gene is called Perpetual Flowering Runnering (PFRU) because it also reduces the number of runners. Growth regulator applications initially demonstrated the role of gibberellin in the control of runner formation, and molecular understanding on the role of gibberellin biosynthesis and signaling in this process has started to emerge. Here, we present current understanding and major open questions on the control of flowering and runnering in strawberries. In order to understand the control of flowering in the context of perennial growth cycle, we also discuss current knowledge on the control of dormancy.