Taxonomic Characters Research Articles

Molecular characterisation and redescription of Ficophagus religiosus (Bajaj & Tomar, 2014) Davies & Bartholomaeus, 2015 from Ficus religiosa in India

Summary A population of Ficophagus was discovered in the syconia of sacred fig (Ficus religiosa) grown in New Delhi (India). Based on morphology, morphometric characters and molecular data, we redescribed the population as Ficophagus religiosus. Here, major morphological characteristics are described in depth, with measurements of the male-female specimens’ taxonomic characters and photomicrography. Ficophagus religiosus can be easily identified by the spiral to J-spiral-shaped body, labial disc not offset, SE pore close to the base of the lip region, stylet length 17.7 (16-19) μm in males, and 19 (15-22) μm in females, a short post-uterine sac of length 8.3 μm (5-10 μm), a spicule with broad and high condylus, capitulum flat or depressed, a small bluntly rounded rostrum, the spicule tip (bluntly rounded or pointed), no cucullus, no gubernaculum, three pairs (P3, P3a, P4) of subventral caudal papillae, and broadly or bluntly rounded tail tip, without mucron. Additionally, new sequence data for the D2-D3 region of 28S rDNA (LSU) and 18S rDNA (SSU) marker genes are provided. Maximum likelihood and Bayesian methods were used to infer phylogenetic relationships of the Indian population of F. religiosus with other Ficophagus species. Phylogenetic analyses based on D2-D3 and SSU molecular markers resulted in a clear separation of F. religiosus from other Ficophagus species. The present study redescribes the species F. religiosus and provides molecular data to identify and establish phylogenetic relationships with other species.

Flower morphology of Allium (Amaryllidaceae) and its systematic significance

Allium is a complicated genus that includes approximately 1000 species. Although its morphology is well studied, the taxonomic importance of many morphological traits, including floral traits, are poorly understood. Here, we examined and measured the floral characteristics of 87 accessions of 74 Allium taxa (belonging to 30 sections and nine subgenera) from Central to Eastern Asian countries. We then examined the taxonomic relationships between select flower characteristics and a phylogenetic tree based on ITS sequences. Our results confirm that floral morphology provides key taxonomic information to assess species delimitation in Allium. We found that perianth color is an important characteristic within the subg. Melanocrommyum, Polyprason, and Reticulatobulbosa. In subg. Allium, Cepa, and Rhizirideum, significant characteristics include ovary shape, perianth shape, and inner tepal apex. For species in subg. Angunium, the key taxonomic character is ovule number (only one ovule in per locule). In the subg. Allium, Cepa, Polyprason, and Reticulatobulbosa, which belong to the third evolutionary line of Allium, hood-like appendages occur in the ovary, although these do not occur in subg. Rhizirideum. Our results also indicated that the flower morphology of several species in some sections are not clearly distinguished, e.g., sect. Sacculiferum (subg. Cepa) and sect. Tenuissima (subg. Rhizirideum). This study provides detailed photographs and descriptions of floral characteristics and information on general distributions, habitats, and phenology of the studied taxa.

TAXONOMIC SIGNIFICANCE OF MORPHOLOGICAL CHARACTERS OF DIAMESA TSUTSUII TOKUNAGA (DIPTERA, CHIRONOMIDAE, DIAMESINAE)

Collection of larvae and male imago of Diamesa tsutsuii (Tokunaga, 1936) (Diamesinae, Chironomidae, Diptera) from a few localities of Sakhalin Island and Primorye stored in the Laboratory of Freshwater Hydrobiology FSCEATB FEB RAS (Vladivostok) is under discussion. A comparison of conchological features with the purpose to check the validity of taxonomic characters is made.

A contribution of leaf anatomy to the taxonomy of Varronia P. Browne (Cordiaceae, Boraginales)

Varronia (Cordiaceae, Boraginales) is a Neotropical genus of approximately 125 species. In Brazil, it is represented by 36 species, of which 21 are endemic. Regarding the vegetative organs, their species are morphologically similar, and despite recent revision studies on the genus, the identification and delimitation of some species are still problematic. In this perspective, we here investigate the leaf anatomy of ten species of Varronia recorded in Brazil, to detect diagnostic taxonomic characters and putative synapomorphies for the genus. The types and distribution of secretory and non-secretory trichomes were identified as one of the most relevant characters in differentiating the studied species. Three types of non-secretory and one type of secretory trichomes are reported in the genus for the first time. The occurrence of crystalline sand in the mesophyll was identified as a putative synapomorphy for the genus, as well as the occurrence of globular and elongated glandular trichomes, isobilateral mesophyll, hypostomatic leaves, and the occurrence of cystoliths.

Current and Future Diversity of Thysanoptera Species in the Cereal Areas of the Lakes Region, Turkey

Field surveys were carried out to determine the thrips fauna in cereal production areas of the Lakes Region in Turkey in 2016 and 2017. Thysanoptera specimens were collected with destructive and strike methods in two periods (before and after spike) from each production field during the production season. Thrips specimens were identified based on morphological taxonomic characters. Species distribution maps, species richness, abundance, as well as Shannon–Wiener (H') index, species seasonal dynamic and species sex ratio were calculated to indicate the diversity of Thysanoptera species in the Lakes Region. We also calculated Pearson correlation coefficient to evaluate correlation between Thysanoptera species richness and host plant richness. Species Distribution Modelling, namely MaxEnt algorithm, was used in order to establish the current and future distributional patterns of Thysanoptera species collected in our research area. During the two years of the study, 27,603 specimens of Thysanoptera were collected in production fields of wheat, oat and barley. There were 51 different species from four families. Haplothrips tritici was the most abundant species with 15,284 specimens or 55.371% of all collected. The highest relative abundance within family Thripidae was recorded for Collembolothrips mediterraneus, Chirothrips manicatus, Thrips angusticeps, Thrips herricki and Limothrips cerealium. Considering the altitudinal gradient of the study area, the highest species richness and abundance were found between 950 and 1,050 m.a.s.l. with 40 species and 7,622 specimens recorded. Potential species richness of Thysanoptera revealed an increase in areas that predominantly encompass eastern parts of Burdur province, as well as central north parts of Isparta.

Oil cells in the side walls of air chambers, a new taxonomic character in the family Marchantiaceae

Comparative studies of oil cells in the air chamber side walls of eight Japanese taxa of Marchantiaceae showed that three morphological groups can be recognized based on this character: (1) Marchantia polymorpha and M. paleacea with conspicuous and whitish oil cells, (2) M. emarginata, M. papillata and M. pinnata with indistinct and nearly hyaline oil cells, and (3) Preissia quadrata without oil cells. This grouping is congruent with the results of existing phylogenetic analyses involving Marchantiaceae taxa. The morphology of oil cells in the side walls of air chambers should be used as a new taxonomic character within the family Marchantiaceae.

Molecular phylogeny of the genus Dorometra Clark, 1917 (Crinoidea: Comatulida: Antedonidae): a new genus and new insights for future taxonomic revisions of Antedonidae

Dorometra Clark, 1917 (Comatulida: Antedonidae) is an Indo-Pacific genus of small-sized cryptic feather stars currently comprising nine species. The monophyly of this crinoid genus has been widely questioned, although only few studies have investigated the phylogeny of Antedonidae in depth. In this study we used an integrated approach combining molecular phylogenetic, morphology, and multivariate analyses to clarify the taxonomic placement of the genus Dorometra within family Antedonidae. Eight of the nine known species of the genus collected from Australia to the Sea of Japan were included in analyses. Phylogenetic analyses using sequences from two mitochondrial (COI, 16S) and one nuclear (28S) genes demonstrate that Dorometra is polyphyletic, and its species are divided into three main clades, which are spread within other Antedonidae. As a result, we herein describe Nesometra gen. nov. Four different species delimitation methods on single and multi-locus alignments also showed higher diversity than previously thought. In particular, our results highlighted the presence of cryptic diversity within the species Dorometra nana (Hartlaub, 1890) in geographically close localities within southern Japan. By multivariate analysis of morphological matrix, we confirmed the homoplasy and plasticity of the taxonomic characters used in the description of Dorometra species, providing a path forward for the general taxonomic revision of this genus and of Antedonidae and related families. http://zoobank.org/urn:lsid:zoobank.org:pub:DB7C239C-5CA0-485B-B4A8-205288FC4080

New leptestherid clam shrimps (Pancrustacea: Branchiopoda: Spinicaudata: Leptestheriidae) from peninsular India.

Spinicaudatan clam shrimps are an evolutionarily ancient lineage restricted to temporary freshwater pools. Use of classical morpho-taxonomic approaches alone have led to some issues in the taxonomy of this group, which are now being resolved through integrative taxonomy. Here, we describe two new leptestherid spiny clam shrimps Leptestheria chalukyae sp. nov. and Leptestheria gomantaki sp. nov. from peninsular India based on their unique morphological characters and distinct phylogenetic position. We also re-describe Leptestheria nobilis and present an overview of the morphological characters of all the Indian leptestherids. Most of the conventional taxonomic characters appear to overlap among all the Indian species, although the combination of occipital condyle shape and the cercopod marginal spines arrangement in combination, appear to be useful in separating leptestherid species.

Pollen morphology of some genera selected tribe Alysseae (Brassicaceae)

The tribe Alysseae (Brassicaceae) contains the genera Brachypus, Clastopus, Fibigia, Irania, Physoptychis, and Straussiella. Little is known about the pollen morphology in these taxa. In this study, pollen from 11 species and one variety representing some of the genera in the tribe Alysseae were examined using light microscopy (LM) and scanning electron microscopy (SEM). The size of pollen is the smallest in Brachypus tabriziana (30.23 µm), conversely, the largest in Irania umbellata (47.17 µm) and Clastopus vestitus (46.60 µm) in the Alysseae. The pollen morphology of Irania umbellata deviated from I. multicaulis and was distinct in having perprolate, ornamentation reticulate, the thickest exine, and the polar axis length. In this study, the pollen morphology of some species of Fibigia, Brachypus, and Irania, was previously placed in the Fibigia genus in order to determine the significance of pollen features as taxonomic characters. In addition, our results indicated that Clastopus differs from the related genera Physoptychis and Straussiella, and pollen morphology conforms to the separation of the three genera. These results support research phylogenetic studies in the Alysseae. Based on the above evidence, the three new combinations such as Brachypus kermanshahensis, B. khoshyelaqensis, and B. tabriziana proposed.

Distribution of the Diatoms and Water Quality Assessment of the Thamirabarani River, Tamil Nadu, South India


 
 
 
 
 
 The diatoms are one of the most significant organisms beneficial for biomonitoring investigations. The present study deals with the diatom and water samples collected from 10 different localities in the Thamirabarani River, Southern India. Diatom samples were collected by scraping stones with a toothbrush and squeezing macrophytes. Study of diatom valve morphology and measurements of diatoms were carried out using an optical miccroscope. The present study recorded 58 diatom taxa belonging to 25 genera. Among the diatoms, the taxonomical characters of 20 abundant diatom taxa viz. Aulacoseira granulata, Discostella stelligera, Navicula cryptocephala, Encyonema minutum, Gomphonema gandhii, Eunotia asterionelloides, Gomphonema parvulum, Brachysira neglectissima, Aulacoseira ambigua, Diadesmis confervacea, Nitzschia palea, Nitzschia amphibia, Sellaphora Americana, Staurosirella pinnata, Gomphonema affine, Fragilaria pararumpens, Eunotia incisa, Navicula erifuga, Navicula cryptotenella and Navicula rostellata are described and illustrated. In the present study abundant diatom genera were observed such as Aulacoseira, Discostella, Navicula, Encyonema, Gomphonema, Brachysira, Nitzschia, Sellaphora, Staurosirella, Fragilaria and Euno- tia. In abundant diatom taxa such as Aulacoseira granulate, Discostella stelligera, Gomphonema gandhii, Fragilaria pararumpens, Navicula cryptocephala, Navicula rostellata, Staurosirella pinnata water quality index values between 21-42 were recorded at Sites 1-9, which indicates unpolluted water. The abundant diatom taxa Diadesmis confervacea, Nitzschia palea, and Gomphonema parvulum were present at Site 10 and a water quality index value of 101 was recorded, indicating water polluted due to anthropogenic activity. The diatom assemblage of the present study was compared with various river systems to understand the environmental condition assessment. The water samples were analysed for assessment of the water quality.
 
 
 
 
 
 
 

Микрорельеф поверхности листьев дикорастущей айвы Cydonia oblonga Mill. (Rosaceae) лесных фитоценозов предгорий Дагестана

Cryo-scanning electron microscopy was used to study the micromorphology of the leaf surface of the wild-growing Cydonia oblonga Mill. (Rosaceae). The only habitat of wild-growing quince in Russia is the southern part of Dagestan. Mountain forest phytocenoses of Dagestan provide unique grounds for studying the adaptive potential of plants, since growing conditions change not only according to the change of seasons, but also directly depend on the altitude above sea level. The adaxial (upper) and abaxial (lower) surfaces of the studied samples have a number of micromorphological and microstructural features. The epidermis on the adaxial and abaxial sides differed not only in structural organization, but also in the specifics of surface micromorphology. The most striking feature of the micromorphology of the adaxial and abaxial sides of the leaf blade surface is cuticular folding in the form of microstrands on the main cells of the epidermis, as well as radial striations, peristomatic rings, and protrusions in the stomata region. Regardless of the habitat of fruit plants, their leaves were hypostomatous with anomocytic stomata of two types (primary and secondary), differing in qualitative and quantitative indicators. The primary stomata had a more prominent cuticular pattern and were also larger than the smaller secondary stomata. It should be noted that the presence of several types of cuticular folding, as well as stomatal polymorphism, are common features of other studied species of the subfamily Pyrinae, early Maloideae (Rosaceae). According to the data obtained, the identified features of cuticular folding are stable within the species and can be used as additional taxonomic characters.

Distinctive foliar features and volatile profiles in three Ambrosia species (Asteraceae).

Ambrosia species differ both in their trichome types and in metabolic profiles of leaf volatiles. The current study provides tools for easier taxonomic identification of ragweed species. The genus Ambrosia (Asteraceae) includes some of the most noxious allergenic invasive weeds in the world. Due to high polymorphism in this genus, identification of species is often difficult. This study focuses on microscopic investigation of foliar features and GC-MS identification of the main leaf volatile components of three Ambrosia species currently found in Israel-invasive species Ambrosia confertiflora and A. tenuifolia, and transient A. grayi. A. confertiflora and A. tenuifolia have three trichome types: non-glandular trichomes, capitate glandular trichomes and linear glandular trichomes. Their non-glandular trichomes and capitate trichomes have distinct structures and can serve as taxonomic characters. A. grayi (the least successful invader) has only very dense covering trichomes. All three Ambrosia species have secretory structures in their leaf midrib. A. confertiflora, the most problematic invasive plant in Israel, had a ten times higher volatiles content than the other two species. In A. confertiflora, the most abundant volatiles were chrysanthenone (25.5%), borneol (18%), germacrene D and (E)-caryophyllene (both around 12%). In A. tenuifolia, the most abundant volatiles were β-myrcene (32.9%), (2E)-hexenal (13%) and 1,8-cineole (11.7%). In A. grayi, the most abundant volatiles were β-myrcene (17.9%), germacrene D (17.8%) and limonene (14%). The three examined species have distinct trichome types and metabolic profiles. Non-glandular trichomes show structural diversification between species and are a good descriptive character. Considering the anthropocentric significance of this highly problematic genus, the current study provides tools for easier identification of ragweed species.

Taxonomic and Otolith Shape Parameters of Nine Sympatric Catfishes Commercially Harvested in Pakistan

Abstract Accurate reorganization of harvested species is essential for appropriate fisheries monitoring but often unnoticed. In this study, an attempt was made to provide an accurate species description based on fish taxonomy and otolith shape parameters of nine sea catfishes living in Pakistan. The lapillus, the largest otolith of catfishes, includes the position of the umbo, the structure of the anterior mesial projection (amp), the incisura linea basalis (ilb) and sulcus lapilli marks (slm) in nine ariid catfishes were evaluated. Discriminant function analysis was performed using twenty-two morphometric parameters showed significant variations between the length of the maxillary barbel, adipose length and preorbital length, which were highlighted as basic discriminating characters. Species without barbells, such as Batrachocephalus mino and Osteogeneiosus militaris, were found to be distant. The taxonomic characters of the genera Netuma and Plicofollis overlapped due to a short adipose fin length. Nevertheless, species Arius arius, Sciades sona and Nemapterxy caelatus differed in a moderate adipose fin length. The preorbital length of Netuma bilineata has a short and rounded snout, while N. thalassina has a long and pointed snout, which is a distinguishing characteristic of both species. The coincident use of fish taxonomy and otolith shape parameters is an effective tool for catfish identification could be helpful in appropriate fisheries sampling programs and management in Pakistan whenever implemented.

A Phylogenetic and Morphological Evolution Study of Ribes L. in China Using RAD-Seq

Ribes L. belongs to the Grossulariaceae family and has important edible, medicinal, ornamental, and landscaping values. Taxonomic classification within this genus is difficult due to its large variety of species, wide distribution, large morphological variations, and presence of two complex taxonomic groups with bisexual or unisexual flowers. Our study aims to clarify the phylogenetic relationships of Ribes L. taxa in China, and further, to provide a reference for a revised global classification of it. The phylogenetic analysis of 52 Ribes L. samples from 30 species was constructed based on restriction site-associated DNA sequencing and single nucleotide polymorphisms. Afterward, two important taxonomic characters were selected for ancestral state reconstruction over the molecular phylogeny. The results showed that the 52 samples could be divided into six branches, i.e., six subgenera, which caused some controversy regarding the morphological classification of Ribes L. in China. The molecular phylogeny supported the separation of subg. Coreosma from subg. Ribesia and subg. Hemibotrya from subg. Berisia and validated the rationale for recognizing subg. Grossularia as an independent subgenus, the rationality of which was further verified by the reconstruction of ancestor traits. Gene flow among Ribes L. was identified and further confirmed our results.

Taxonomic revision of the Merodon tarsatus species group (Diptera, Syrphidae)

The phytophagous hoverfly genus Merodon Meigen, 1803 (Diptera, Syrphidae) presently comprises 205 described species distributed in the Palaearctic and Afrotropical regions, and it is differentiated into multiple species groups. In this work, we revise the Merodon tarsatus species group, providing an illustrated key to species, a detailed discussion on relevant taxonomic characters, and a morphological diagnosis. We summarize morphological characteristics of the 12 species in the M. tarsatus group, together with available distributional data. Moreover, we provide descriptions for five new species, namely Merodon angustitarsis Vujić & Gilasian sp. nov., M. dumosus Vujić, Likov & Radenković sp. nov., M. latiantennatus Vujić, Popov & Prokhorov sp. nov., M. namaghijamii Vujić, Likov & Radenković sp. nov. and M. pakistanicus Vujić, Likov & Radenković sp. nov. Additionally, we describe one more species, Merodon nigroalatus Vujić, Likov & Radenković sp. nov., that belongs to the same lineage and is related to the Merodon tarsatus group based on molecular markers and structure of male genitalia, but lacks modifications of the metatarsus and sternum 4 that are the main diagnostic features of the group. Furthermore, we redefine and redescribe seven taxa of the M. tarsatus group. Following detailed analyses of type material, we revise the status of all available taxa related to M. tarsatus and we propose the following new synonyms: M. ankylogaster Hurkmans, 1993 syn. nov. (junior synonym of M. hypochrysos Hurkmans, 1993); M. persicus Hurkmans, 1993 syn. nov. (junior synonym of M. oidipous Hurkmans, 1993); and M. xanthipous Hurkmans, 1993 syn. nov. (junior synonym of M. marginicornis Hurkmans, 1993). We apply Maximum Parsimony and Maximum Likelihood analyses of the 5′ end of the mitochondrial COI gene sequences to genetically characterize species in the M. tarsatus group and the related species, M. nigroalatus Vujić, Likov & Radenković sp. nov.

Ascospore morphology of bryophilous Pezizales is closely associated with the place of infection and host ecology

Fungal spores are morphologically highly diverse and are therefore frequently used as diagnostic characters in taxonomy. However, the connection between spore morphology and fungal ecology remains poorly understood. Using phylogenetic comparative analyses, we investigated the putative relationships between four ascospore traits and the dominant place of infection, host ecology, and host taxonomic placement in 123 species of biotrophic parasites of bryophytes. Ascospore shape, ornamentation height and relative lipid content are significantly correlated in bryophilous Pezizales. Species attached by their hyphae to bryophyte rhizoids have more globose ascospores with higher ornamentation and relative lipid content than species attached to aboveground organs. Furthermore, some ascospore traits are significantly associated with host lifespan, habitat preferences, and taxonomic placement of their host bryophytes. Our results suggest that the ascospore morphology in this fungal group is closely linked to its ecology and several of the detected relationships point to the existence of distinct dispersal strategies. • Multiple ascospore traits are significantly correlated in bryophilous Pezizales • Ascospore morphology is closely associated with characteristics of host bryophytes • Diverse ascospores in this group likely reflect differences in dispersal strategies • Requirements for longer survival could play a crucial role in ascospore evolution

A Review Study on The Taxonomic, Phytochemical, And Pharmacological Characteristics Of “Small-Flowered Snakeroot” (Rauwolfia micrantha, Hook. F.)

India is one of the 12 mega-diversity countries in the World and has 47,000 plant and 89,000 animal species ranking the country sixth for harboring the largest number of threatened plant species. This unique land mass of India has one of the most varied tropical and subtropical climates, altitudinal ranges reaching up to 2,800 m, and many edaphic conditions. The mentioned factors confer a variety of micro-climatic/ecological niches that nurture one of the richest endemic flora of peninsular India. With its exceedingly environmentally heterogeneous biogeographic area, the Western Ghats as a whole is an abode of rich diverse flora. The present work has been conducted to review and assess the taxonomic characters, phytochemical properties, and pharmacological uses of Rauwolfia micrantha. Rauwolfia micrantha is an important evergreen, woody, shrub used in the modern medical system and also in Ayurveda, Unani, and folk medicine. It is also a source of pharmacologically important active chemicals and alkaloids. The data obtained from the present study will help in understanding the potential and importance of Rauwolfia micrantha and assert the significance of its conservation through micropropagation and other biotechnological tools.

Additions to the Morphology of the Cucumariidae. I. Intraspecific Variation of the Retractor Muscle in Parathyone braziliensis (Verrill, 1868) and Thyonidium seguroensis (Deichmann, 1930) (Holothuroidea: Dendrochirotida)

Intraspecific variation of the gross morphology of the retractor muscle was studied in 60 specimens of Parathyone braziliensis and 17 specimens of Thyonidium seguroensis. Specimens were dissected to expose the retractor muscle or were analyzed by micro-computed tomography. Early expectations that the point of origin of the retractor muscle at the longitudinal muscle relative to the midpoint of the body length was age-related and that the split of the retractor muscle into separate muscle bands could be used as taxonomic characters to separate species were not supported by anatomical evidence.

New Records of Wood- and Bark-Inhabiting Nematodes from Woody Plants with a Description of Bursaphelenchus zvyagintsevi sp. n. (Aphelenchoididae: Parasitaphelenchinae) from Russia.

Wood- and bark-inhabiting parasitic nematodes are of great economic importance. Nematodes can cause wilt diseases in conifers and deciduous trees. In 2014-2022, during nematology surveys conducted in different regions of Russia and Belarus, adults and dauer juveniles of nematodes were collected from wood, bark and beetle vectors. Using traditional morphological taxonomic characters integrated with molecular criteria, we identified in the studied samples the following nematode species: Aphelenchoides heidelbergi, Bursaphelenchus eremus, B. fraudulentus, B. michalskii, B. mucronatus, B. willibaldi, Deladenus posteroporus, Diplogasteroides nix and Laimaphelenchus hyrcanus, several unidentified species: Aphelenchoides sp.1 and sp.2, Cryptaphelenchus sp.1, sp.2 and sp.3, Laimaphelenchus sp.1, Micoletzkya sp.1, Parasitaphelenchus sp.1, Parasitorhabditis sp.1, three unidentified tylenchid nematodes and a new species, Bursaphelenchus zvyagintsevi sp.n. Morphological descriptions and molecular characterization are provided for B. zvyagintsevi sp. n. belonging to the Abietinus group and B. michalskii belonging to the Eggersi group. Findings of Aphelenchoides heidelbergi, Bursaphelenchus eremus, B. michalskii, Deladenus posteroporus, Diplogasteroides nix and Laimaphelenchus hyrcanus are new records for Russia. Phylogenetic positions of studied species were reconstructed using D2-D3 expansion segments of 28S rRNA gene sequence analysis. The data obtained in this study may help to detect the refugia of opportunistic plant pests and find possible native biocontrol nematode agents of insect vectors causing diseases.

Genome-wide identification and expression analysis of AUX/LAX family genes in Chinese hickory (Carya cathayensis Sarg.) Under various abiotic stresses and grafting.

Auxin is essential for regulating plant growth and development as well as the response of plants to abiotic stresses. AUX/LAX proteins are auxin influx transporters belonging to the amino acid permease family of proton-driven transporters, and are involved in the transport of indole-3-acetic acid (IAA). However, how AUX/LAX genes respond to abiotic stresses in Chinese hickory is less studied. For the first time identification, structural characteristics as well as gene expression analysis of the AUX/LAX gene family in Chinese hickory were conducted by using techniques of gene cloning and real-time fluorescent quantitative PCR. Eight CcAUX/LAXs were identified in Chinese hickory, all of which had the conserved structural characteristics of AUX/LAXs. CcAUX/LAXs were most closely related to their homologous proteins in Populus trichocarpa , which was in consistence with their common taxonomic character of woody trees. CcAUX/LAXs exhibited different expression profiles in different tissues, indicating their varying roles during growth and development. A number of light-, hormone-, and abiotic stress responsive cis-acting regulatory elements were detected on the promoters of CcAUX/LAX genes. CcAUX/LAX genes responded differently to drought and salt stress treatments to varying degrees. Furthermore, CcAUX/LAX genes exhibited complex expression changes during Chinese hickory grafting. These findings not only provide a valuable resource for further functional validation of CcAUX/LAXs, but also contribute to a better understanding of their potential regulatory functions during grafting and abiotic stress treatments in Chinese hickory.