Taxonomic Traits Research Articles

Spore morphology of Adiantum species from the Indian sub-continent using LM and FESEM: Palaeoecological analysis and Phylogenetic delineation

ABSTRACT The palynology of fern spores has proven to be an immensely useful tool in the identification and phylogenetic characterization of various fern taxa. A diverse range of spore morphologies have been studied yet, nevertheless, the investigation of 21 species of Adiantum under Light Microscopy (LM) and Field Emission Electron Microscopy (FESEM) is a maiden attempt from India to develop a spore micro-morphometric dataset that complies with taxonomic traits, fossil counterparts, and evolutionary changes. All the studied spores of Adiantum species possess significant differences in lete character (aperture, primary character); exospores ornamentation (secondary character); and spore shape (tertiary character). The sexine pattern varies from psilate to verrucate, scabrate to granulate, and rugulate to fossulate (eurypalynous type). The perine is a characteristic feature of the fern spores as evident in A. myriosorum, A. zollingeri, and A. philippense, suggesting the diversity among different Adiantum spores. The multivariate statistical analysis indicates three major clusters based on spore morphological characteristics. The evolutionary outcome of this micro-morphometric analysis showed that the spore of A. formosum is composed of the most primitive characters (such as unconstricted lete arm, smooth exospore, and non-perinate sclerine), whereas the spores of A. zollingeri and A. myriosorum comprised advanced characters (such as constricted lete arms, rugulate exospores, and perinate sclerine). This extensive spore morphological examination would provide a comprehensive dataset for the identification of fossil spores (up to the species level) and taxonomic characterization of Adiantum species in India and its comparison with other species growing around the world.

The Potential Role of Phytoplankton Functional Groups Under Anthropogenic Stressed Wetlands: Characterizing The Environmental Sensitivity.

Anthropogenic and climatic changes are continuously altering the freshwater plankton, necessitating an evaluation of the complex structure of plankton communities to understand and mitigate these impacts. In this context, the present study focuses on evaluating the structure of plankton communities, specifically Phytoplankton Functional Groups (FGs) for assessing the environmental sensitivity of wetlands under changing scenario. These FGs are defined by shared adaptive features rather than taxonomic traits. Over the period from 2016 to 2018, two ecologically distinct wetlands were examined, analysing their phytoplankton FGs and their relationship with water quality parameters. Ecohydrological data revealed significant seasonal variations (p ≤ 0.05) in key parameters such as water depth, temperature, pH, electrical conductivity, dissolved oxygen, total alkalinity, total hardness, NO3-N, and PO4-P. Notably, there were no significant differences observed among the sampling stations within each wetland. A total of 125 phytoplankton genera/species were classified into 23 FGs in the open wetland and 22 FGs in the closed wetland. Spatial and seasonal analyses of dominant FGs suggested both wetlands were experiencing pollution pressures. This study highlights the powerful role of phytoplankton functional groups (FGs) as bioindicators of wetland health, uncovering pollution pressures. In open wetlands, 15 phytoplankton FGs with 36 key taxa (Indicator Value ≥ 40%) emerged as critical indicators, while in closed wetlands, only 10 FGs with 17 taxa were identified. To assess eutrophication, the occurrence of these indicator species was evaluated using BVSTEP function analysis. The study recommends pollution reduction in catchment areas and restoration of riverine connectivity to enhance FG diversity. Phytoplankton FG methodologies are deemed effective for assessing the environmental sensitivity of wetlands significantly impacted by human activities. This research offers a scientific foundation for the evaluation and restoration of wetland ecosystems.

Phylogenetic evaluation and haplotype mapping of phytoplasma disease in sesame: insights into leafhopper-mediated disease transmission through molecular investigation

The predominance of leafhopper species like Orosius albicinctus, Hishimonus phycitis, and Amrasca biguttula biguttula indeed poses a significant threat to sesame production in India and globally. This disease is a major challenge for sesame farming, as it can lead to yield reductions of up to 95%. The current study examined phytoplasma and leafhoppers in sesame and analyzed the phylogenetic differences in the phyllody phytoplasma. The identification of both 16Sr group I and group II phytoplasma isolates, along with the discovery of the 16SrI-B group reported for the first time in Tamil Nadu, represents a significant advancement in our understanding of phytoplasma diversity in the region. The utilization of virtual RFLP analysis in sequencing the sesame phyllody phytoplasma highlights the importance of molecular techniques in characterizing the phytoplasma. Leafhoppers in sesame were a co-occurring species complex of O. albicinctus, H. phycitis, and A. bigutulla bigutulla. The leafhoppers were identified using species-specific taxonomical traits, and a mtCOI gene-based genetic study confirmed the species. In disease transmission efficiency studies in the greenhouse, O. albicinctus transmitted phyllody at a rate ranging from 7.8% to 84%, while H. phycitis transmitted phyllody at a rate of 5.2% to 74%. Both of these species showed the highest transmission efficiency in the combination of three insects per plant with five days of acquisition feeding and one day of inoculation feeding. A comprehensive understanding of leafhopper-phytoplasma interactions through molecular studies supports effective monitoring, early detection, and the development of integrated pest management strategies.

Copper and cadmium co-contamination increases the risk of nitrogen loss in red paddy soils

The microbiome plays a crucial role in soil nitrogen (N) cycling and in regulating its bioavailability. However, the functional and genomic information of microorganisms encoding N cycling in response to copper (Cu) and cadmium (Cd) contamination is largely unknown. Here, metagenomics and genome binning were used to examine microbial N cycling in Cu and Cd co-contaminated red paddy soils collected from a polluted watershed in southern China. The results showed that soil Cu and Cd concentrations induced more drastic changes in microbial N functional and taxonomic traits than soil general properties. Soil Cu and Cd co-contamination stimulated microbial nitrification, denitrification, and dissimilatory nitrate reduction processes mainly by increasing the abundance of Nitrospira (phylum Nitrospirota), while inhibiting N fixation by decreasing the abundance of Desulfobacca. These contrasting changes in microbial N cycling processes suggested a potential risk of N loss in paddy soils. A high-quality genome was identified as belonging to Nitrospirota with the highest abundance in heavily contaminated soils. This novel Nitrospirota strain possessed metabolic capacities for N transformation and metal resistance. These findings elucidate the genetic mechanisms underlying soil N bioavailability under long-term Cu and Cd contamination, which is essential for maintaining agricultural productivity and controlling heavy metal pollution.

A new white-flowered Elleanthus (Orchidaceae: Sobralieae) from the Andes of southern Ecuador and notes on hummingbird pollination of Elleanthus scopula

A new species of Elleanthus from southern Ecuador is described and illustrated here. Elleanthus loxensis is characterized by having ramified stems with coriaceous, plicate leaves and white flowers. Its ecological, morphological, and taxonomic traits are compared with other similar species within the genus and discussed here. Additionally, comments on the pollination of Elleanthus scopula are presented.

Phytoseius Ribaga (Mesostigmata: Phytoseiidae) in the Brazilian Espinhaço Range: seven new species, renaming of the plumifer species group, and a critical review of its taxonomic characters

The mountainous regions in eastern Brazil are home to an astonishing variety of Phytoseius (Mesostigmata: Phytoseiidae) species, 11 of which were collected in surveys conducted between 2010–2012. Our study revealed a great diversity in the plumifer species-group, in which we describe seven new taxa, P. maspretiosus sp. nov., P. multilunatus sp. nov., P. trisetatus sp. nov., P. itobira sp. nov., P. dasalmas sp. nov., P. bahiensis sp. nov., and P. paucipapillatus sp. nov.. This enabled us to compare close species in this group determining valid diagnostic characters, providing a critical review of the prevailing taxonomic traits and revealing unexpected patterns in important diagnostic features based on our observations and the literature. Moreover, we claim the taxonomic importance of two morphological traits usually mentioned in previous studies, but never exploited to their full potential: the female pattern of dorsal ornamentation and the shape of the male spermatodactyl. Aware of the incongruity that the exemplar species of the plumifer group, P. plumifer (Canestrini & Fanzago), belongs to the horridus species group, we propose that the group be renamed as mexicanus-species group. A key to the Brazilian species of Phytoseius is included.

Exploring genetic diversity of yellow-berried night shade (Solanum virginianum L.) using genetic divergence and molecular markers

The rationale of this research was to explore the genetic divergence of 54 kantakari accessions (Solanum virginianum L. syn. S. surattense Burm. f.), to identify their significant traits, and unravel their genetic variations. Kantakari is a widely used medicinal plant in traditional medicine worldwide and is also known for its allopathic properties. The morphological descriptors and molecular markers (Random Amplified Polymorphic DNA) used to characterize these samples revealed significant within-accession heterogeneity, indicating the possibility of future selection. Twenty-three morphological and biochemical features were examined to assess taxonomic traits. Accessions were classified into six clusters based on Mahalanobis D2 statistics of 23 quantitative traits. Clusters V and VI had the largest intercluster distance (1183.81), whereas Cluster IV had the largest intracluster distance (D2 = 275.67) (Cluster V and VI). Random Amplified Polymorphic DNA marker amplification using 10 polymorphic primers revealed 79 alleles with an overall mean of 7.90 alleles per marker, with Polymorphism Information Content values varying from 0.11 to 0.37 (Mean = 0.30). Cluster assessment produced three distinct groups. In conclusion, the investigation underscores that substantial diversity was observed among the surveyed kantakari accessions. Using molecular markers in tandem with morphological characterization, presents a robust approach for elucidating the intricacies of species-specific genetic variation with greater accuracy and depth.

Embryogeny of Pleuroxus aduncus (Jurine, 1820) and Chydorus sphaericus S. Lato (Müller, 1776) indicate on conservative instars development among family Chydoridae (Crustacea, Cladocera, Anomopoda)

The embryogenesis of the family Chydoridae, in which 60 genera are recognized, is poorly understood compared to that of the family Daphniidae, which contains only five genera. Therefore, studies of the evolution of Anomopoda suffer from a paucity of data on chydorids. Here, I studied the embryogenesis of two cladocerans, Pleuroxus aduncus and Chydorus sphaericus s. lato of the Chydoridae, using scanning electron microscopy. Various ontogenetic stages were compared with those of Dunhevedia crassa, as described by Kotov etal. (2013). I confirmed an evolutionarily conserved pattern of instar development among these three species. Cladoceran families were analysed in relation to their numbers of thoracopods, an important taxonomic trait, and the numbers of thoracopods in ancestral states were proposed. Chydorus sphaericus s. lato lacks six thoracopods in the adult stage, but this study revealed their brief presence during embryonic development.

A Comparative Morphological Study on the Characteristics of Egg Envelopes of Three Cultrinae Fishes (Cyprinidae, Teleostei) in Korea.

Three species of subfamily Cultrinae currently live in Korea, but Erythroculter erythropterus has been introduced into the Nakdonggang River and has taken over the habitat, reducing the habitat of Culter brevicauda. Only the endangered species C. brevicauda still lives in the Yeongsangang River, and it is necessary to be careful not to introduce E. erythropterus in the future. Hemiculter eigenmanni is also found throughout the country. In order to effectively manage and conserve the species in its various habitats and against invasions, this study was initiated. The ultrastructure of the egg envelopes of three species of Cultrinae inhabiting the Geumgang and Yeongsangang Rivers-E. erythropterus, C. brevicauda, and H. eigenmanni-were observed. It was found that the zona radiata of the egg envelopes of all three species were divided into two layers, an outer and inner layer, with the outer surface having a non-structural form. This form is characteristic of fishes with muddy, stagnant habitats or spawning grounds. The number of pore canals on the surface of the egg envelopes was 83 for E. erythropterus, 75 for C. brevicauda, and 58 for H. eigenmanni per 10 μm2, and the thickness was 7.89 ± 0.34 μm, 12.27 ± 0.46 μm, and 7.42 ± 0.24 μm, respectively. The shape of the micropyle demonstrated a funnel shape narrowing toward the inner diameter in all three species, and the size of the inner diameter was 6.62 ± 0.29 μm in E. erythropterus, 4.19 ± 0.39 μm in C. brevicauda, and 3.98 ± 0.46 μm in H. eigenmanni. The differences between species were identified in the number of pore canals, thickness, and micropyle inner diameter of egg envelopes, which were species-specific. Our study reveals a morphological mechanism in the egg envelope that prevents the formation of interspecific hybrids, and these features can be taxonomic traits that clarify species names. It also provides useful data for the production (breeding) of the second generation in aquaculture.

Hormonal profiles in dormant turions of 22 aquatic plant species: do they reflect functional or taxonomic traits?

Turions are vegetative, dormant overwintering organs formed in aquatic plants in response to unfavourable ecological conditions. Contents of cytokinin (CK), auxin metabolites and abscisic acid (ABA) as main growth and development regulators were compared in innately dormant autumnal turions of 22 aquatic plant species of different functional ecological or taxonomic groups with those in non-dormant winter apices in three aquatic species and with those in spring turions of four species after their overwintering. The hormones were analysed in miniature turion samples using ultraperformance liquid chromatography coupled with triple quadrupole mass spectrometry. In innately dormant turions, the total contents of each of the four main CK types, biologically active forms and total CKs differed by two to three orders of magnitude across 22 species; the proportion of active CK forms was 0.18-67 %. Similarly, the content of four auxin forms was extremely variable and the IAA proportion as the active form was 0.014-99 %. The ABA content varied from almost zero to 54 µmol kg-1 dry weight and after overwintering it usually significantly decreased. Of all functional traits studied, hormone profiles depended most on the place of turion sprouting (surface vs bottom) and we suggest that this trait is crucial for turion ecophysiology. The key role of ABA in regulating turion dormancy was confirmed. However, the highly variable pattern of the ABA content in innately dormant and in overwintered turions indicates that the hormonal mechanism regulating the innate dormancy and its breaking in turions is not uniform within aquatic plants.

Species delimitation and taxonomic revision of the Ptilagrostis dichotoma species complex (Poaceae) based on statistical morphological variations

Abstract Statistical morphological variations at the population level serve as a robust foundation for species delimitation and taxonomic treatment. We employed this approach to investigate species delimitation within the Ptilagrostis dichotoma species complex (Poaceae), which is characterized by open panicles. While three species have been described, the boundaries between these species and the morphological distributions of all taxonomic traits remain unclear. In this study, we examined the geographical variability of 19 morphological traits based on at least six individuals from each of the 28 populations across the entire distributional range of the species complex. Our statistical analyses identified five distinct phenotypic clusters with specific geographical preferences. Three of these clusters corresponded to the previously described species, while the remaining two clusters represented previously undescribed species. Furthermore, our findings highlight several traits, such as basal leaf scabrosity, panicle branch pulvinae, and glume length, which exhibit distinct gaps between phenotypic units and prove highly valuable for species delimitation. Finally, two new species are described and a key is provided to differentiate the five species. This morphological revision establishes a basis for future studies on species boundaries and divergences of the complex based on other evidence.

In situ observation on two ‘elusive’ rhodaliid siphonophores (Cnidaria; Hydrozoa; Siphonophora) from the Red Sea, including a potential new species within the genus Archangelopsis

Rhodaliids, a specific family of siphonophores inhabiting the benthic zone, have remained enigmatic due to their rarity and elusive nature. These unique organisms, primarily found in open ocean habitats, exhibit distinctive features and are characterized by complex structures. During the Red Sea Decade Expedition, two rhodaliid specimens were collected at the sea bed at water depths of 438 and 495 meters. Regardless of challenges in specimen preservation, detailed morphological analysis revealed unique characteristics. Genetic analysis, employing the 16S rRNA marker, revealed one specimen closely related to Thermopalia taraxaca, while the taxonomic traits of this specimen suggested the identification of Archangelopsis jagoa. While most of the morphological features of the second specimen were also very similar to A. jagoa, some differences in coloration suggest the discovery of either an unusual colour variant or a potential new species within this genus. Notably, this study reports the first sequencing of A. jagoa. This species demonstrated a capacity to thrive in low-oxygen environments, challenging conventional assumptions about their habitat requirements. Despite difficulties in specimen handling and genetic analysis limitations due to a lack of comprehensive data, this research sheds light on the elusive world of benthic rhodaliids.

Characterization of Starch Granaule of Local Water Yam (Dioscorea alata L.) from Lermatang, Tanimbar Island District, Maluku

Most tuberous crops, for instance, the yam, whose scientific name is Dioscorea alata, have food reserves in the form of starch in tubers. Characterization of starch grains of a plant species is pertinent to uncover information on plant taxonomic traits and identify their potential use as food and industrial raw materials. The study aimed to determine the characteristics of starch grains of water yam from Lermatang village, Tanimbar Islands Regency. This study isolated and submitted six accessions of water yam in Lermatang Village. The morphological inspection of the plants used the Descriptor for Yam from IPGRI, and sample preparation for observing starch grains employed the fresh section method. The six accessions of D. alata found in Lermatang village, Tanimbar Islands, were Uwi Merah, Uwi Gula, Uwi Pingingsian, Uwi Babulu, Uwi Akiakab, and Uwi Petatas. These yam varieties show differences in their tubers' shape and colors. The study found that starch granules of D. alata in each accession varied in terms of granule shape and hilus type. The starch granules revealed dominant triangular, oval, and elliptical shapes and eccentric and concentric hilus types. The starch grain diameter in the six accessions of Uwi was categorically large (44.88 – 57.5 µm), with Uwi Petatas being the largest. Previous reports have shown that accessions having large starch granule types could be further developed into an array of foods, thus conveying the promising use of the Uwi Petatas for such a purpose.

Changes in soil microbial functions involved in the carbon cycle response to conventional and biodegradable microplastics

Biodegradable mulch film has become an encouraging alternative to conventional petroleum–based plastic, but it is likely to generate more microplastics (MPs) than conventional films with lower resistance and thus profoundly affects the soil environment. However, the effects of biodegradable (BMPs) and conventional polyethylene MPs (PE–MPs) on soil microbial carbon (C) cycle remain unclear. Here, metagenomic sequencing was used to investigate microbial functional and relative taxonomic traits in response to PE–MP and BMP addition (5 % w/w) via a soil microcosm experiment. The results showed that the presence of BMPs, rather than PE–MPs, significantly changed soil microbial C cycling patterns at the functional and taxonomic levels. In soils, BMP addition significantly increased the abundances of genes regulating aerobic respiration, C decomposition (intracellular), C fixation, fermentation and CO oxidation pathways compared to those in the control and PE–MP added soils. Specifically, BMPs promoted soil starch and PHA (liable C) degradation, acetate and ethanol fermentation, Calvin–Benson–Bassham (CBB) cycle and 3–hydroxypropionate/4–hydroxybutyrate (3HP/4HB) associated with C fixation. Most of these C cycling pathways were further strengthened in the microplastisphere of BMPs. Furthermore, MPs selectively enriched specific taxa on their surface and subsequently increased their abundance in soils; Bradyrhizobium, Ramlibacter and Variovorax (enriched by BMPs) positively regulated labile C degradation, and Amycolatopsis and Nocardia (enriched by PE–MPs) promoted recalcitrant C degradation. Moreover, Pseudonocardia and Variovorax that were enriched by BMPs improved C dissimilation and assimilation by regulating fermentation and C fixation processes, respectively. Taken together, these results improve the understanding of the influence of conventional and biodegradable MPs on soil C cycling pathways and related microbial communities, highlighting that the presence of BMPs rather than PE–MPs accelerates soil C turnover.

New insights on the taxonomy of Diadumene paranaensis (Cnidaria: Actiniaria) associated with mangrove roots in the Brazilian semi-arid coast.

A dense estuarine aggregation of Diadumene paranaensis Beneti, Stampar, Maronna, Morandini & Da Silveira, 2015 associated with Rhizophora mangle L. was found at the Arpoeiras Beach, mouth of Acaraú River, Ceará, Brazilian semi-arid coast. Here, we compare biological and taxonomical traits with the type material, collected from the portuary zone of Paranaguá Bay, and propose modifications in the diagnosis of the species, as well as of the family Diadumenidae and genus Diadumene, to align with the description of our specimens. In addition, we discuss its tolerance to high salinity and predict a much broader geographic range for this sea anemone in Brazil.

Microstructural and histochemical analysis of shoots and cones of Juniperus seravschanica (Cupressaceae).

Juniper species contain abundant compounds that are used in the medicine, cosmetic, and wood industry. Furthermore, these components protect the genus against herbivores, pathogens and detrimental abiotic conditions. Stains and specific reagents can be used individually or simultaneously to mark cell shape, arrangement and the material they are made from. Microchemical analyses using specific reagents and stains under light microscopy are helpful for the characterization of chemical compounds present in plant tissues. The autofluorescence of endogenous fluorophores is used to enable their localization in plant cells and tissues. This paper aims to investigate the cytochemical and histochemical traits of the shoots (leaves and stems) and female cones (berries) of Juniperus seravschanica. Light and florescent microscopy techniques were used to analyze the cytology and localization of different compounds for the first time. Microscopy-based histochemical analyses revealed various products in terms of composition and distribution among the shoots and female cones. These specific compounds contained lignin, tannins, polysaccharides, starch, phenolic compounds, chlorophyll, terpenoids, neutral lipids, and proteins. However, the anatomical position of each metabolite and its concentration was different among leaf, stem, and female cone. Phenolic cells of young cones were differentiated into sclereid cells during development. The density of phenolic cells, sclereid cells, and resin glans was higher in female cones than leaves and stems. The high levels of various components can be related to high resistance of the species against biotic and abiotic stresses, confirm its industrial, pharmaceutical and agricultural applications and is useful for identification of diagnostic taxonomic traits. RESEARCH HIGHLIGHTS: Microscopical and histochemical analyses showed various compounds in J. seravschanica The phenolic cells differentiated to sclereid cells during development High levels of idioblasts and various compounds show its high resistance and medicinal role.

Exploring the molecular mechanism of coloration differences in two Meconopsis wilsonii subspecies: australis and orientalis

Flower color diversity is a key taxonomic trait in Meconopsis species, enhancing their appeal as ornamental flowers. However, knowledge of the molecular mechanisms of flower color formation in Meconopsis species is still limited. M. wilsonii subsp. australis (Australis) and M. wilsonii subsp. orientalis (Orientalis) have a developmental stage presenting red-purple flowers, while Orientalis also presents blue coloration at the full-bloom period, making them an important model for exploring the mechanism of blue flower formation in M. wilsonii. In this study, we collected petals from Australis and Orientalis at different developmental stages to compare the coloration differences between the two species and detect the molecular mechanisms of blue color in Orientalis. We identified that cyanidin was the main anthocyanin in the flowers of both species, and the blue color in Orientalis primarily arises from anthocyanins (Cyanidin-3-O-sambubioside). RNA sequencing analysis was performed to detect the gene expression in the anthocyanin biosynthesis pathway, and the results suggested that gene regulation for anthocyanin biosynthesis may not be the direct reason for blue color formation in Orientalis. In addition, the growth solid of Orientalis was rich in Fe and Mg ions, and a large amount of Fe and Mg ions accumulated in the petals of Orientalis. Combined with the gene functional enrichment results, we found that the purple and red-purple colors of these two species were presented by different glycosylation levels of cyanidin, while the violet color of Orientalis might be the results of metalloanthocyanins by Fe and Mg ions, which also relieved the toxicity caused by the high content of Fe and Mg ions in its cells. The environmental adaptation-related genes were highly expressed of in both species, such as adaptation to desiccation, water deprivation, freezing, etc. Our results revealed the coloration differences between Australis and Orientalis and described the molecular mechanisms of blue coloration in Orientalis. The data in our analysis could enrich the genetic resources for M. wilsonii for further studies.

Indian record of the old-world psyllid Heterotrioza chenopodii (Reuter) (Hemiptera, Psylloidea, Triozidae) on quinoa Chenopodium quinoa (Amaranthaceae)

The Old-World Psyllid, Heterotrioza chenopodii (Hemiptera, Psylloidea, Triozidae) was found infesting quinoa, Chenopodium quinoa (Amaranthaceae) crop. The psyllids were identified using taxonomic traits and further confirmation with mitochondrial marker based molecular approach. The information on damage and its life stages is reported along with the phylogenetic information of the species. The identity, analysis in NCBI indicated that the MT-COI sequences of H. chenopodii were 96 per cent identical to the previously deposited sequences with NCBI and five submissions with accession numbers were made viz., OP735496, OP740826, OP740828, OP740829 and OP740830. The phylogenetic tree represented the similarities in the analyzed sequences Indian populations are found to be merged in between the other similar global populations.

Long-term adjustment of phytoplankton structure to environmental traits at timescales during lifetime development and over generations

Long-term ecological research of deep Lake Mondsee covers over more than six decades of phytoplankton observation. According to our study, phytoplankton groups of various phenological traits are suitable to address the impact of two major environmental stressors: nutrient surplus by eutrophication from 1968 to 1998 and warming by climate change. Here, we focus on phytoplankton biovolume, phytoplankton assemblage structure, net changes rates, and phytoplankton biodiversity. Biweekly net change-dependent persistence of phytoplankton assemblages followed a dome-shaped relationship of observations. A short-term persistence of taxonomic traits along weeks is predominant and contributes to the structural stabilization of phytoplankton assemblages. This short-term persistence is interpreted by the benefit of lifetime adjustment of phytoplankton organisms. The long-term development phytoplankton structure is discussed as an alignment of organisms over generations. Single key taxa, as Planktothrix rubescens (De Candolle ex Gomont) Anagnostidis &Komárek 1988, which are omnipotent players in phytoplankton assemblages and occur during different environmental scenarios in the long-term, are most suitable for long-term ecological research. Our findings interpret that phytoplankton taxa are excellent organisms to track the impact of environmental constraints due to their short generation time (1), their lifetime adjustment (2), and the re-occurrence in the long-term over generations (3).

High yielding mutants from the introgression lines of groundnut (Arachis hypogaea L.)

An effort was made to generate variability for foliar disease resistance and productivity traits in groundnut using induced mutagenesis with gamma rays and ethyl methane sulfate (EMS) in three interspecific derivatives viz., ICGIL17105, ICGIL 17110, and ICGIL 17112 involving ABK genomes. A large population of M1, M2, M3 and M4 generations were evaluated along with the parents and checks to identify the promising mutants. Germinationpercentage decreased with an increase in the dosage of mutagen individually and in combination in the M1 generation. Dominant mutants with reduced plant height were observed along with the lethal mutants in the M1 generation. Gamma rays of 300 Gy and 0.3% EMS showed the highest mutagenic frequency and effectiveness for foliar disease resistance [late leaf spot (LLS) and rust] and productivity traits in the M2 generation. Interestingly, mutations were also observed for the taxonomic traits. Evaluation of M3 lines confirmed the superiority of three mutants over the respective parents and the best check (GPBD 4) for foliar disease resistance and pod yield. Superior mutants were checked for the type of allele at late leafspot (LLS) and rust resistance linked marker loci. Parents and the mutants had the resistant type of allele (like GPBD 4) at all the marker loci (GM1536, GM1954, GM2301, AhTE0498 and AhTE0621). Superior mutants are being evaluated in large plots in the station trial along with the parents and other elite varieties to check their performance towards developing them into commercial varieties.