Dichotomous Branching Research Articles

Devaleraea titlyanoviorum sp. nov. (Palmariaceae, Rhodophyta) from the Russian coast of the northwestern Pacific Ocean

ABSTRACT One species of the red algal genus Devaleraea, D. stenogona, shows remarkable phenotypic plasticity over its geographic range. We assumed this species to be a complex of morphologically close species. To resolve this issue, we sequenced the internal transcribed spacer (ITS) regions, including the 5.8S rDNA, rbcL, and 5′ end of the COI gene (COI-5′) of specimens of D. stenogona sensu lato from different localities along the Russian coast of the northwestern Pacific Ocean. We also compared their morphology with the holotype and to specimens of D. stenogona from the type locality. Morphological and genetic analyses confirmed that Devaleraea stenogona sensu lato is a complex of two congeneric species and, therefore, the new species D. titlyanoviorum sp. nov. is proposed. This species is characterised by abundantly proliferating thalli, with proliferations being larger than the main blade. First-year non-proliferating plants can be confused with D. stenogona, but they differ by a more regular dichotomous branching and by the shape of terminal branches, which are strap-shaped with rounded tips in D. titlyanoviorum and narrow-linear or hair-like with acute tips in D. stenogona. The species have different geographical distributions with D. stenogona occurring further south than D. titlyanoviorum.

Changes in Root Architecture and Aboveground Traits of Red Clover Cultivars Driven by Breeding to Improve Persistence

Red clover persistence has been one of the major targets for the most breeding programs worldwide. A phenotypic characterization at above- and belowground level was performed to a set of highly persistent red clover populations. The objective was to identify phenotypic changes occurring after empirical selection for plant survival, which is the consensus criteria of persistence. Eleven red clover populations were established on mesocosms of polyvinyl chloride (PVC) tubes of 11 cm in diameter and 100 cm depth, containing as substrate a mixture (v/v) of sand, vermiculite, soil and perlite. The trial was organized in a randomized complete block design with four replicates, each replicate consisting of five mesocosms per population and one plant per mesocosm. In total, 220 mesocosms were handled. At aboveground level, growth parameters, specific leaf area (SLA) and shoot dry matter (ShootDM) were measured. At belowground level, root morphology (volume, diameter and length) and topology (altitude, external path length [EPL] and dichotomous branching index [DBI]) were measured through image analyses. Analyses of variance were performed implementing a phenotypic linear mixed model using the Restricted Maximum Likelihood method. Additionally, variance components were estimated and broad-sense heritability was calculated for each phenotypic trait. Highly persistent cultivars exhibited 30% higher ShootDM and 10% lower leaf size and SLA than the oldest low-persistent cultivar Quiñequeli. At root level, they showed 20, 50 and 50% higher crown diameter, root length density and root volume than Quiñequeli, respectively, but 20% lower DBI. Root traits exhibited medium-low values of genetic control; broad sense heritability ranged between 0.20 and 0.48. In conclusion, highly persistent red clover cultivars and experimental lines bred in Chile modified their phenotypic expression of individual plants at shoot and root levels relative to the oldest low persistent cultivar Quiñequeli. Associations among above- and belowground traits offer opportunities for designing more efficient selection strategies. For instance, the strong relationship between SLA and root traits offers tremendous potential for indirect phenotypic selection.

FEATURES OF FETAL ANATOMY OF THE SUBMANDULAR DUCT

Knowledge of the patterns of the formation of the structure and topography of organs and systems of the human body is important for the interpretation of the true direction of the processes of organogenesis, the mechanisms of normal morphogenesis of organs, the emergence of anatomical variants and congenital defects. The interest in continuing the research was initiated by the buildup of an integrative approach in scientific developments, which, together with the doctrine of the individual anatomical variability of organs, systems and the shape of the human body, is the foundation of medicine. The next movement in this direction is the study of the variability of the shape of the submandibular strait of the human submandibular salivary gland during intrauterine development. Using the methods of macro-copy, microscopy, graphic and plastic reconstruction, fine preparation under the control of a binocular loupe, morphometry on 111 objects (60 before a person's fetus 7-12 weeks of intrauterine development and 51 fetuses of 4-10 months of intrauterine development were studied Variants of the form of the submandibular strait and the frequency of its manifestations in prenatal and human fetuses are from the rudiment of the tongue. At the beginning of the prefetal period of human ontogenesis, the rudiment of the gland increases significantly and takes the form of a continuous epithelial cord, which is represented by a large number of dividing cells. during the prefetal period with the rudiment of the submandibular duct of the submandibular salivary gland, a number of regular sequential changes occur: 1 – the formation of numerous epithelial cords of the II, III, IV order, as dichotomous branches from the main (main) epithelial anlage, 2 – the formation of a cavity (canal ) in the main epithelial bud and its ramifications of the II-IV order; 3 – the concentration of mesenchymal cells surrounding the epithelial cords (the formation of the mesenchymal part of the submandibular strait of the submandibular salivary gland) with its clear separation from adjacent tissues. In the group of objects of study, most often (76 cases, or 68.47%) there is a direct form of the submandibular ducts; the arcuate variant of the form of the submandibular ducts is almost three times less (26 cases, or 23.42%); as a variant of the form – the S-shaped form of the submandibular duct – was observed even less often (9 cases, or 8.11%).

A Branch-and-Price Framework for Decomposing Graphs into Relaxed Cliques

We study the family of problems of partitioning and covering a graph into/with a minimum number of relaxed cliques. Relaxed cliques are subsets of vertices of a graph for which a clique-defining property—for example, the degree of the vertices, the distance between the vertices, the density of the edges, or the connectivity between the vertices—is relaxed. These graph partitioning and covering problems have important applications in many areas such as social network analysis, biology, and disease-spread prevention. We propose a unified framework based on branch-and-price techniques to compute optimal decompositions. For this purpose, new, effective pricing algorithms are developed, and new branching schemes are invented. In extensive computational studies, we compare several algorithmic designs, such as structure-preserving versus dichotomous branching, and their interplay with different pricing algorithms. The final chosen branch-and-price setup produces results that demonstrate the effectiveness of all components of the newly developed framework and the validity of our approach when applied to social network instances.

A new calcaxonian genus and family for Trichogorgia utinomii Cordeiro, 2019 (Octocorallia, Alcyonacea): new records of a scleriteless gorgonian species from Antarctica

A new genus of scleriteless gorgonian, Huziogorgia gen. nov., is proposed based on the morphological and molecular study of a set of colonies identified as the recently described species Trichogorgia utinomii Cordeiro, 2019. Huziogorgia utinomii comb. nov. has planar colonies, lyrate to dichotomous, with long and flexible terminal branches. The polyps are no retractile, always extended, slightly trumpet-shaped, biserially placed, but not strictly. The axis is circular in cross section, showing concentric non-undulated layers. The materials were collected during three Antarctic cruises to the Antarctic Peninsula and South Shetland islands onboard the RV Polarstern (ANT XIX/3, ANT XXIII/8, and ANT XXIX/3). A molecular comparison based on mitochondrial genes (mtMutS and mtMutS+Igr1+COI) relates the new genus to the family Ifalukellidae Bayer, 1955 (Ifalukella Bayer, 1955, Trichogorgia (Hickson, 1904), Plumigorgia Nutting, 1910) and some genera of uncertain relationships, but currently related to the family Chrysogorgiidae Verrill, 1883 (Pleurogorgia Versluys, 1902 and Stephanogorgia Bayer & Muzik, 1976). Genetic distances between this species and the closest genera and families also suggest the separate placement of Huziogorgia gen. nov. in a new family, Huziogorgiidae fam. nov.

Exploring human splenic red pulp vasculature in virtual reality: details of sheathed capillaries and the open capillary network

We reconstructed serial sections of a representative adult human spleen to clarify the unknown arrangement of the splenic microvasculature, such as terminal arterioles, sheathed capillaries, the red pulp capillary network and venules. The resulting 3D model was evaluated in virtual reality (VR). Capillary sheaths often occurred after the second or third branching of a terminal arteriole and covered its capillary side or end branches. The sheaths started directly after the final smooth muscle cells of the arteriole and consisted of cuboidal CD271++ stromal sheath cells surrounded and infiltrated by B lymphocytes and macrophages. Some sheaths covered up to four sequential capillary bifurcations thus forming bizarre elongated structures. Each sheath had a unique form. Apart from symmetric dichotomous branchings inside the sheath, sheathed capillaries also gave off side branches, which crossed the sheath and freely ended at its surface. These side branches are likely to distribute materials from the incoming blood to sheath-associated B lymphocytes and macrophages and thus represent the first location for recognition of blood-borne antigens in the spleen. A few non-sheathed bypasses from terminal arterioles to the red pulp capillary network also exist. Red pulp venules are primarily supplied by sinuses, but they also exhibit a few connections to the capillary network. Thus, the human splenic red pulp harbors a primarily open microcirculation with a very minor closed part.

Вплив системи догляду за кроною на декоративність і довговічність рослин сортів Syringa vulgaris L.

Досліджено вплив способів обрізування крони рослин Syringa vulgaris L. на їхню декоративність і довговічність. Встановлено, що досягти найкращого результату можна тільки за регулярного догляду за кроною. Спонукає до цього, щонайперше, дихотомічне (несправжнє) гілкування, за яким кожна однорічна гілка продукує навесні два пагони з верхівкової пари бруньок та ще кілька – з бруньок, що розташовані нижче по осі цієї гілки. Отже, щороку загальна їхня кількість щонайменше потроюється. Коренева система не зможе за цей час збільшити в таких обсягах свою масу і фізіологічну активність, що корелятивно спричиняє значне зменшення розмірів пагонів і суцвіть. Якщо догляд був нерегулярний або відсутній, виникає потреба інтенсивного прорідження або кардинального омолодження крони. Доведено, що цими заходами можна поліпшити декоративність рослин, але на довговічність вони вплинуть негативно. Зумовлює це дві причини. Перша – запобігання ран внаслідок видалення гілок на кільце. Встановлено, що навіть 1,5-2,0-сантиметрові зрізи на стовбурі чи скелетних гілках ніколи не загояться, а за 10-15 років їхня деревина струхліє, утворивши порожнину. Деревина великих ран руйнується швидше, що призводить до виникнення дупел та повільного відмирання всієї рослини. Другою причиною вкорочення довговічності є раптово порушений функціональний корелятивний коренево-листковий зв'язок, що є наслідком різкого зменшення в омолодженій рослині надземної частини. Спочатку це призведе до сповільнення фотосинтезу (крона майже відсутня), а потім, корелятивно, й до затухання кореневого синтезу: через мізерне надходження асимілятів до коренів. Унаслідок цього загальна маса фізіологічно активної частини кореневої системи теж значно зменшиться, що негативно вплине на довговічність рослини загалом. Декоративність кущів через це з року в рік погіршується. Також встановлено, що до обрізування крони змушує й загущена посадка бузків. Для відновлення її декоративності спочатку варто видалити кволі рослини, а в решти – знизити крону приблизно на третину аби наблизити її до кореневої системи, що забезпечить рослинам фізичну витривалість та дещо внормує в них функціональний коренево-листковий зв'язок. Здійснити цей захід треба якомога раніше в часовому вимірі, бо, окрім згаданого, рослини почнуть страждати й від хвороб. Потужні гілки потрібно вкорочувати, а не вирізати на кільце, аби не нанести стовбурам і гілкам першого порядку великих ран. За такого підходу до обрізування крони бузки будуть декоративними й здебільшого випадків – довговічними.

Induction of Multichotomous Branching by CLAVATA Peptide in Marchantia polymorpha

A key innovation in land plants was the evolution of meristems with stem cells possessing multiple cutting faces (division planes) from which three-dimensional growth is derived in both haploid (gametophyte) and diploid (sporophyte) generations [1-3]. Within each meristem exists a pool of stem cells that must be maintained at a relatively constant size for development to occur appropriately [4-6]. In flowering plants, stem cells of the diploid generation are maintained by CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) peptide signaling [7, 8]. In the liverwort Marchantia polymorpha, the haploid body undergoes dichotomous branching, an ancestral characteristic of growth derived from the meristem, in which two equivalent body axes are developed via stem cell division, regulated by unknown molecular mechanisms. We show here that in M.polymorpha, treatment with MpCLE2/CLAVATA3 (CLV3) peptide resulted in the accumulation of undifferentiated cells, marked by MpYUC2 expression, in the apical meristem. Removal of MpCLE2 peptide resulted in multichotomous branching from the accumulated cells. Genetic analysis demonstrated that the CLAVATA1 (MpCLV1) receptor, but not the WUSCHEL-related HOMEOBOX (MpWOX) transcription factor, is responsible for MpCLE2 peptide signaling. In the apical meristem, MpCLV1 was expressed broadly in the central region, including the MpYUC2-positive area, whereas MpCLE2 was expressed in a largely complementary manner compared to MpYUC2, suggesting MpCLE2 mediates local cell-to-cell communication. CLV3/CLE peptide, a negative regulator of diploid stem cells in flowering plants, acts as a haploid stem cell-promoting signal in M.polymorpha, implicating a critical role for this pathway in the evolution of body plan in land plants.

Lycopodium root meristem dynamics supports homology between shoots and roots in lycophytes.

Roots have played a pivotal role in the conquest of land by vascular plants, yet their origin has remained enigmatic. Palaeobotanical evidence suggests that roots may have originated from subterranean shoots in some lycophyte species. If this hypothesis is correct, it would follow that the roots and shoots of extant lycophytes share fundamental developmental mechanisms. We tracked meristem dynamics in root and shoot apices of Lycopodium clavatum using a thymidine analogue and expression patterns of histone H4, respectively. Then we compared the meristem dynamics of roots and shoots to identify developmental similarities. Both apical meristems contained a quiescent tissue characterised by a low frequency of cell division. Actively dividing cells appeared in the quiescent tissue during dichotomous branching of both roots and shoots. As a result, the parental meristem divides into two daughter meristems, which give rise to new root or shoot apices. These striking similarities in meristem dynamics provide new neobotanical data that support the shoot-origin hypothesis of lycophyte roots. Although Lycopodium roots may have originated from subterranean shoots of Devonian lycophytes, these shoots may have changed into root-bearing axes in other extant lycophyte lineages.

Mutation of MEDIATOR 18 and chromate trigger twinning of the primary root meristem in Arabidopsis.

Plants adapt to soil injury and biotic stress via cell regeneration. In Arabidopsis, root tip damage by genotoxic agents, antibiotics, UV light and cutting induces a program that recovers the missing tissues through activation of stem cells and involves ethylene response factor 115 (ERF115), which triggers cell replenishment. Here, we show that mutation of the gene encoding an MED18 subunit of the transcriptional MEDIATOR complex and chromate [Cr(VI)], an environmental pollutant, synergistically trigger a developmental program that enables the splitting of the meristem in vivo to produce twin roots. Expression of the quiescent centre gene marker WOX5, auxin-inducible DR5:GFP reporter and the ERF115 factor traced the changes in cell identity during the conversion of single primary root meristems into twin roots and were induced in an MED18 and chromate-dependent manner during the root twinning events, which also required auxin redistribution and signalling mediated by IAA14/SOLITARY ROOT (SLR1). Splitting of the root meristem allowed dichotomous root branching in Arabidopsis, a poorly understood process in which stem cells may act to enable whole organ regeneration.

Multiple branching and attachment structures in cloudinomorphs, Nama Group, Namibia

Abstract The Ediacaran-Cambrian cloudinomorphs, which include Cloudina, are the first putative skeletal metazoans. They have a benthic ecology and tubular, organic, or biomineralized stacked funnel morphologies but an unresolved phylogenetic affinity. Rare dichotomous branching has been described in Cloudina, but here we demonstrate the presence of multiple (polytomous), dichotomous branching in cloudinomorphs from a microbial mat community from the Nama Group, Namibia, as revealed by three-dimensional models created from serial sections. Branches share an open, central cavity, and branching is achieved via external budding. These cloudinomorphs show attachment and mutual cementation to each other, and also to Namacalathus, via extratubular skeletal structures to potentially form a horizontal framework. Polytomous branching excludes a bilaterian affinity as proposed for other cloudinomorphs. This raises the possibility that the Ediacaran tubular, funnel morphology is convergent, and that cloudinomorphs may, in fact, represent taxa of diverse affinity.

Multiple origins of dichotomous and lateral branching during root evolution.

Roots of extant vascular plants proliferate through lateral branching (euphyllophytes) or dichotomy (lycophytes)1-4. The origin of these distinct modes of branching was key for plant evolution because they enabled the development of structurally and functionally different root systems that supported a diversity of shoot systems3-6. It has been unclear when lateral branching originated and how many times it evolved4,7,8. Here, we report that many euphyllophytes that were extant during the Devonian and Carboniferous periods developed dichotomous roots. Our data indicate that dichotomous root branching evolved in both lycophytes and euphyllophytes. Lateral roots then evolved at different times in three major lineages of extant euphyllophytes-the lignophytes, ferns and horsetails. The multiple origins of dichotomous and lateral root branching are extreme cases of convergent evolution that occurred during the Devonian and Carboniferous periods when the land-plant flora underwent a radiation in morphological diversity.

Identification of Telocytes in the Pancreas of Turtles-A role in Cellular Communication.

The existence of telocytes (TCs) has not yet been established in the pancreases of aquatic reptiles. Here, we report TCs in the exocrine pancreas of Pelodiscus sinensis using transmission electron microscope (TEM), immunohistochemistry (IHC), and immunofluorescence (IF) techniques. TCs surrounded the acini and ducts of the connective tissue of the exocrine pancreas and between lobules and gland cells. The cells were located preferably close to the blood vessels, interlobular ducts, and nerve fibers. Ultrastructurally, TCs exhibited small and large bodies with thick and thin portions, podoms, and podomers, and prolongations that form dichotomous branching with hetero-cellular and homo-cellular junctions. The podom (thick) portions showed caveolae, mitochondria, rough endoplasmic reticulum, and vesicles. The nucleus carries heterochromatin and is irregular in shape. The shape of TCs depends on the number of telopodes (Tps) bearing long, short, spindle, triangular, and “beads on a string” shapes with twisted, tortuous prolongations and ramifications. Shed extracellular vesicles and exosomes were found frequently released from projections and Tps within connective tissue in the vicinity of the acini and collagen fibers. IHC and IF results showed CD34+, α-SMA+, and vimentin+, long and triangle-shaped TCs, consistent with the TEM findings. The presence of shaded vesicles from TCs might implicate their possible role in immune surveillance, tissue regeneration as well as regulatory functions in the reptilian pancreas.

New seriated Amathia species in Japan, with a redescription of A. acervata Lamouroux, 1824 (Bryozoa: Ctenostomata).

The status of seriated Amathia species (Bryozoa: Ctenostomata) in Japan is reviewed. Several historical specimens and materials recently collected from several localities along the Japanese coast are examined in this study. Amathia acervata Lamouroux, 1824, collected from Japan by Wilhelm Gottlieb Tilesius in 1804, was examined and is redescribed from a reconstituted fragment of the sole type specimen. Material previously reported from Wakayama Prefecture is very similar to Amathia acervata, but differs in having fewer autozooid pairs per cluster, which spiral in different directions; the species is described as a new species Amathia brevisilva n. sp. Measurements of colony characters vary according to the effects of fixation, but stolon length, the ratio of autozooid clusters on stolons, spirality and pigmentation are useful characters for the identification of Japanese seriated Amathia. In addition, two new species are described, Amathia reptopinnata n. sp. and Amathia fimbria n. sp. Amathia reptopinnata n. sp. is characterized by its robust form, dark colour, dichotomous branching, long stolons, long autozooidal clusters and pinnately arranged prostrate zooids. Amathia fimbria n. sp. was found only in the Showa Emperor collection, and is characterized by its compact colony form, remarkably short internode length and trichotomous branching.

PRIMARY LARYNGEAL ASPERGILLOSIS IN AN IMMUNOCOMPETENT PATIENT

Background. Aspergillus is an inherently ubiquitous, weakly pathogenic fungus causing opportunistic infections. It is very rarely localized in the larynx, although laryngeal Aspergillosis may develop in the immunocompromised patients including those with leukaemia and severe aplastic anaemia.
 Objective. The aim of the research was to explore the primary laryngeal Aspergillosis in an immunocompetent patient thru a case report.
 Methods. A case report of primary laryngeal Aspergillosis in an immunocompetent patient is presented.
 Results. A male patient of 40 years old, presenting with chronic worsening hoarseness, was found to have a smooth, white spheroid submucosal growth on left vocal cord with preserved bilateral cord movements on videostroboscopy. Histopathological examination of vocal cord growth revealed squamous epithelium containing septate hyphae with acute angle dichotomous branching pattern consistent with Aspergillus. Voice improved after a four-week course of oral itraconazole 200 mg/day. Post therapy follow up of 24 months was unremarkable.
 Conclusions. Primary laryngeal Aspergillosis develops in the immunocompetent patients. Iatrogenic, vocal abuse, occupation and lifestyle factors may be contributory. Optimal diagnosis and management mandates a high index of suspicion.

Морфологічні особливості селезінки гусей

The spleen of 2-month-old clinically healthy geese of a large gray breed (n=5) has been studied. The material has been fixed in 10% aqueous solution of neutral formalin and embedded into paraffin. Serial histological sections have been stained with hematoxylin and eosin, fuchsin-aniline-blue-orange by Mallory, azur II - eosin. It has been established that the prevalent structures of the white pulp of the spleen of the 2-month-old geese are presented by periarterial and periellipsoid lymphoid sheaths. Periarterial lymphoid sheaths are detected as masses of lymphoid tissue around the pulpal arteries, most of which are oriented radially and form tree-like branches of the central arteries. The periellipsoid white pulp is represented by lymphoid sheaths along the penicillary capillaries. It occupies a significant area of white pulp and is light islets of mostly round and longitudinally convoluted form, which contain from 2 to 6 sections of penicillary capillaries, in places with their pronounced dichotomous branching. The periellipsoid white pulp in the spleen of birds is considered as the equivalent of the marginal zone of the lymphoid nodules of the mammalian spleen. Lymphoid nodules were detected in the amount of 6-8 in the area of the transverse section of the organ, namely, in the places of branching of the pulpal arteries into central ones. All compartments of the white pulp are connected with the arterial pulp channel. The architectonics of the pulpal part of the arterial bed on longitudinal sections of the spleen of geese has a pronounced main type of branching. 2-3 pulpal arteries depart from the trabecular artery, which are directed radially into the pulp, branching into the central arteries, and the latter into the penicillary capillaries. The mass of lymphoid tissue, concentrated around all the main branches of one pulpal artery, allows us to distinguish the morphofunctional units of the white pulp – segments, which indicates the segmental type of structure of the spleen parenchyma of geese. Parenchyma segments are surrounded by red pulp formed by pulpal cords with venous sinuses and pulpal veins.

<p><strong>Notes on the genus <em>Zeravschania </em>(Apiaceae) with description of two new species from Afghanistan and Iran</strong></p>

Two species of Apiaceae are described as new to science: Zeravschania khorasanica from the Khorasan Province, eastern Iran, and Z. podlechii from the Ghor Province, central Afghanistan. Zeravschania khorasanica is related to Z. regeliana and Z. scabrifolia, but differs in rigid remains of petioles and sheaths, deeply laciniate ultimate segments of leaves, and broad-keeled ribs of mericarps. Zeravschania podlechii differs from other species of the genus in multiple stems, short internodes, dichotomous branching, and an unusual life form (сushion plant). In addition, Z. knappii is transferred to the genus Dichoropetalum on the basis of morphological evidence.

Deletion of the small GTPase rac1 in Trichoderma reesei provokes hyperbranching and impacts growth and cellulase production

BackgroundTrichoderma reesei is widely known for its enormous protein secretion capacity and as an industrially relevant producer of cellulases and hemicellulases. Over the last decades, rational strain engineering was applied to further enhance homologous and heterologous enzyme yields. The introduction of hyperbranching is believed to increase protein secretion, since most exocytosis is located at the hyphal apical tip. There are several genetic modifications which can cause hyperbranching, for example the deletion of the small Rho GTPase rac. Rac plays a crucial role in actin dynamics and is involved in polarisation of the cell during germination and apical extension of the hyphae.ResultsWe deleted rac1 in a T. reesei strain with an ectopically overexpressed endoglucanase, CEL12A, under Pcdna1 control. This deletion provoked a hyperbranching phenotype and strong apolar growth during germination and in mature hyphae. The strains displayed dichotomous branching and shorter total mycelium length with a larger hyphal diameter. Δrac1 strains exhibited a decreased radial growth on solid media. Biomass formation in liquid cultures was carbon source dependent; similar to the reference strain during growth on lactose, increased on d-glucose and slightly enhanced on cellulose. While extracellular cellulase activities remained at parental strain levels on d-glucose and cellulose, the specific activity on lactose cultures was increased up to three times at 72 h accompanied by an upregulation of transcription of the main cellulases. Although the morphology of the Δrac1 strains was considerably altered, the viscosity of the culture broth in fed-batch cultivations were not significantly different in comparison to the parental strain.ConclusionsDeletion of the small Rho GTPase rac1 changes the morphology of the hyphae and provokes hyperbranching without affecting viscosity, independent of the carbon source. In contrast, biomass formation and cellulase production are altered in a carbon source dependent manner in the Δrac1 strains.

Dark Septate Endophyte Improves Drought Tolerance of Ormosia hosiei Hemsley & E. H. Wilson by Modulating Root Morphology, Ultrastructure, and the Ratio of Root Hormones

Dark septate endophytes (DSEs) are known to help host plants survive drought stress; however, how DSEs enhance host plant drought resistance under water stress conditions remains unclear. The objective of this study was to inoculate Ormosia hosiei seedlings with a DSE strain (Acrocalymma vagum) to investigate the effects of DSE inoculation on root morphology, ultrastructure, and the endogenous hormone content under drought stress conditions and to elucidate the drought resistance mechanism involved in the DSE–host-plant association. The inoculated seedlings were grown under three different soil water conditions (well watered—75% field water capacity, moderate water—55% field water capacity, or low water—35% field water capacity) for 114 days. Fresh root weight, root volume, root surface area, root fork, and root tip number were significantly higher in inoculated seedlings than in noninoculated seedlings. Furthermore, the root architecture of the inoculated seedlings changed from herringbone branching to dichotomous branching. Mitochondria and other organelles in root cells of inoculated seedlings remained largely undamaged under water stress, whereas organelles in root cells of noninoculated seedlings were severely damaged. The abscisic acid (ABA) and indole-3-acetic acid (IAA) content and IAA/ABA ratio of inoculated seedlings were significantly higher than those of noninoculated seedlings, whereas the content of gibberellic acid (GA) and the ratios of GA/ABA, zeatin riboside (ZR)/ABA, and ZR/IAA in inoculated seedlings were lower than those of noninoculated seedlings. DSE inoculation could help plants adapt to a drought stress environment by altering root morphology, reducing ultrastructural damage, and influencing the balance of endogenous hormones, which could be of great significance for the cultivation and preservation of the O. hosiei tree.

The Seasonal Growth Dynamics of Fucus distichus subsp. evanescens (C. Agardh) H.T. Powell, 1957 (Phaeophyceae: Fucales) in the Avacha Bay (Southeastern Kamchatka)

The peculiarities of the linear growth and morphogenesis of the commercial brown alga Fucus distichus subsp. evanescens from the Avacha Bay (southeastern Kamchatka) were studied during the period from April 1 to October 7, 2017. Fucus plants were divided into five size groups (Groups 1 to 5) of five labeled plants each. The observations were conducted at spring ebb tides; we measured the length of dichotomous branches of each order regularly, one to two times per month, and determined their increase and the state of maturity of apical branches. During the period of our field observation, labeled plants formed from four to six new dichotomous branches. Moreover, the plants with only one dichotomy in April had a higher growth rate than those that had three to five dichotomous branches at the beginning of the studies. By the end of the observations, plants with one, two, three, four, and five dichotomous branches became bushes with seven, seven, eight, eight, and nine dichotomies, respectively. The absolute growth rate of the investigated plants of F. distichus subsp. evanescens varied from 23.2 to 36.7 mm per month with the maximum value of 2.33 mm per day recorded in June. Thus, Fucus displayed more active growth than previously believed. This allows us to consider these brown algae as a potential object for introduction to mariculture. Since Kamchatka representatives of the species can form several dichotomous branches during one vegetation season, the number of dichotomies is not an indicator of the age of algal plants, as was previously suggested.