Botany

Naturally endowed with a coastline of about 8,000 Km represented in a wide range of ecosystems like estuaries, mangroves, backwaters, salt marshes, sandy beaches, rocky coasts, coral reefs, and many such variations in ecosystem diversity, India is also predictably blessed with a treasure of marine biotic resources. A conservative estimate of about 80% of all such resources is found in the coastal zones. Such diversity is attributed to the complex habitats created by the dominant benthic primary producers along with the phytoplankton of the productive shallow waters, further stimulated by terrestrial inputs and upwelling incidents. The primary producers that belong to the heterogeneous assemblage of ‘algae’ are the most important contributors to ecosystem functions in such regions. Distribution patterns and regional assemblage composition of algal species worldwide have been important fields of study. Recent studies suggest that energy and habitat area play an important role in determining the present-day distributional patterns observed for marine algae along with the role of historical processes. A discussion on the utilization status of such resources in India starts on the note that India has quite a phenomenal resource base. The three most important contributors to such resources include the red algae, brown algae and green algae. The current paper deals with a review and discussion of the extent of marine resources in India, their use and sustainability issues and a special note on the algal resources of Sundarbans and the potential use patterns of the same.

Geothermal springs are mostly formed due to tectonic movements of the earth or volcanic eruptions leading to the release of hot water in the form of artesian wells. The environment is very suitable for the growth of thermophilic Cyanobacteria. Nevertheless, some members of Bacillariophyceae (diatoms) are also found in such geothermal springs, although, very high water temperature and alkaline water is generally not very conducive for diatom growth. The present study involves report and enumeration of 16 species of heat resistant diatoms for the first time from two different sites of the hot springs of Bakreswar. The sites vary considerably in terms of temperature and anthropogenic pressures. The genera - Coscinodiscus sp., Synedra sp., Pinnularia sp., Rhopalodia sp., Gomphonema sp., Hantzschia sp. etc. form important constituents of the diatom assemblages. The study establishes lower Species Richness (9) at higher temperatures (>48ºC) which is the Reserve Tank (Site-1) compared to Species Richness (13) at lower temperatures (35–37ºC) in the Bathing Tank (Site-2). The study also highlights the abundance of pennate forms at lower temperatures. Most of the species are common at both the sites barring Gomphoneis sp., Coscinodiscus oculus-iridis and Coscinodiscus radiatus. None of the centric diatoms belonging to the genera Coscinodiscus were found to occur at Site-2.

Diatoms are microscopic, unicellular, eukaryotic algae belonging to the Class
Bacillariophyceae which are abundant in most aquatic habitats and serve as useful proxies
for multi-dimensional analysis of ecosystems. They inhabit waters and soils of both saline and
freshwater areas. Diatoms as primary producers are vital for life on Earth, serve as
significant source of oxygen, have major impact on global carbon cycle and are food source
for many organisms at other trophic levels. Moreover, diatoms provide an exceptional tool for
examining environmental changes. Data on diatom abundance and diversity, both living and
fossil are found to be very useful in environmental studies, since they are extremely sensitive
to and respond rapidly to environmental changes with specific species being adapted to a
particular environment. Most importantly, after death their silica frustules sink to the bottom,
get added to the sedimentary records and preserve well within most sediments as
diatomaceous earth. Diatom analysis has been undertaken across all continents to reconstruct
past environments and a lot of attention goes out to develop techniques of modeling recent
climate variability. Such diatom assemblages preserved at variable depths in sedimentary
sequences have proven to be excellent proxies for inferring climate change events,
catastrophic events and other stochastic variability of the environment. The diatom
assemblages are also interpreted in combination with geochemistry and sedimentary
characteristics for complete reconstructions of past environments and logical modeling for
future trends. The present paper is a review of the available publications that have added to
the significance of diatom assemblages in soil as palaeo-ecological indicators.Diatoms are microscopic, unicellular, eukaryotic algae belonging to the Class
Bacillariophyceae which are abundant in most aquatic habitats and serve as useful proxies
for multi-dimensional analysis of ecosystems. They inhabit waters and soils of both saline and
freshwater areas. Diatoms as primary producers are vital for life on Earth, serve as
significant source of oxygen, have major impact on global carbon cycle and are food source
for many organisms at other trophic levels. Moreover, diatoms provide an exceptional tool for
examining environmental changes. Data on diatom abundance and diversity, both living and
fossil are found to be very useful in environmental studies, since they are extremely sensitive
to and respond rapidly to environmental changes with specific species being adapted to a
particular environment. Most importantly, after death their silica frustules sink to the bottom,
get added to the sedimentary records and preserve well within most sediments as
diatomaceous earth. Diatom analysis has been undertaken across all continents to reconstruct
past environments and a lot of attention goes out to develop techniques of modeling recent
climate variability. Such diatom assemblages preserved at variable depths in sedimentary
sequences have proven to be excellent proxies for inferring climate change events,
catastrophic events and other stochastic variability of the environment. The diatom
assemblages are also interpreted in combination with geochemistry and sedimentary
characteristics for complete reconstructions of past environments and logical modeling for
future trends. The present paper is a review of the available publications that have added to
the significance of diatom assemblages in soil as palaeo-ecological indicators.

Bacterial wilt, caused by the soil-borne pathogen Ralstonia solanacearum is an important disease of tomatoes, causing plant death and significant yield losses. The three known antagonistic organisms Bacillus subtilis, Pseudomonas aeruginosa (KUCd1) and Trichoderma viride were tested under in vitro and in vivo conditions against Ralstonia solanacearum. B. subtilis showed a significant antagonistic effect when pre-inoculated before the pathogen. Both under in vitro and green house conditions, a combination of the two bacteria Bacillus subtilis and Pseudomonas aeruginosa (KUCd1) in equal proportion also lowered the disease incidence by 51-55%.The studies indicate the efficacy of B. subtilis and the consortium of Bacillus subtilis  and Pseudomonas aeruginosa (KUCd1) as potential bio-control agents against the bacterial wilt of tomato.

Identification of the cause of disease is the most important step towards its eradication, cure and management. India being an agro-based country, plant diseases alone cause immense economic loss to the tune of rupees 500 crores every year. In this study, we focus on reportedly one of the most devastating diseases called bacterial wilt. Though each bacterial type has a set of host range, recent study shows frequent overlapping of susceptible host plants. Besides, several new species have been identified in recent times that cause wilt in plants. There are lots of similarities in the disease manifestation and molecular identification has been quite effective in proper identification of the pathogens. In this study, management of wilt mainly briefs the methods adopted against Ralstonia solanacearum. Other than physical and chemical methods , management of the disease by use of antagonistic bacteria and fungi has been found to be the recent trend.

Ralstonia solanacearum is known to be the most prominent causal agent of bacterial wilt worldwide. It has a wide host range comprising solanaceous and nonsolanaceous plants. Typical symptoms of the disease are leaf wilt, browning of vascular tissues, and collapsing of the plant. With the objective of studying the diversity of pathogens causing bacterial wilt in West Bengal, we collected samples of diseased symptomatic crops and adjacent symptomatic and asymptomatic weeds from widespread locations in West Bengal. By means of a routine molecular identification test specific to " R. solanacearum species complex " , the majority of these strains (68 out of 71) were found to not be R. solanacearum. Presumptive identification of these isolates with conventional biochemicals, extensive testing of pathogenicity of a subset involving greenhouse trials fulfilling Koch's postulate test, and scanning electron microscopic analysis for the presence of pathogen in diseased plants were done. 16S rDNA sequencing of a subset of these strains (GenBank accession Nos. JX880249–JX880251) and analysis of sequences with the nBLAST programme showed a high similarity (97%–99%) to sequences of the Enterobacteriaceae group available in GenBank. Molecular phylogeny further established the taxonomic position of the strains. The 3 bacterial strain cultures have been submitted to MTCC, Institute of Microbial Technology, Chandigarh, India, and were identified as Klebsiella oxytoca, Enterobacter cowanii, and Klebsiella oxytoca, respectively. Although Enterobacter sp. has previously been reported to cause wilt in many plants, susceptibility of most of the dedicated hosts of R. solanacearum to wilt caused by Enterobacter and other bacteria from Enterobacteriaceae is being reported for the first time in this work. Résumé : Ralstonia solanacearum est assurément l'un des principaux agents du flétrissement bactérien a ` l'échelle mondiale. Sa large gamme d'hôtes comprend des plantes de la famille des solanacées et d'autres plantes. Les symptômes caractéristiques de la maladie sont le flétrissement des feuilles, le brunissement des tissus vasculaires et l'effondrement de la plante. Dans l'optique d'étudier la diversité des pathogènes causant le flétrissement bactérien dans l'ouest du Bengale, on a effectué des prélèvements chez des cultures symptomatiques malades et des mauvaises herbes adjacentes avec et sans symptômes un peu partout dans cette région. Un test courant de dépistage moléculaire de bactéries du complexe de R. solanacearum a révélé que la majorité des souches (68 sur 71) n'étaient pas R. solanacearum. On a procédé a ` une identification présomptive de ces isolats par biochimie conventionnelle, a ` une analyse détaillée de la pathogénicité d'un sous-groupe ayant réussi un test de vérification des postulats de Koch d'après des essais en serre, et a ` une analyse par MET recherchant le pathogène dans des plantes affectées. Un séquençage de l'ADNr 16S d'un sous-ensemble de ces souches (numéros d'entrée GenBank JX880249–JX880251) et l'analyse des séquences par le programme nBLAST ont fait ressortir un degré de similitude élevé (97–99 %) avec les séquences du groupe des Enterobacteriaceae présentes dans GenBank. La phylogénie moléculaire a corroboré la position taxonomique des souches. Les trois cultures de souches bactériennes ont été envoyées au MTCC de l'Institut de Technologie Microbienne a ` Chandigarh, Inde, lequel les a identifiées comme étant Klebsiella oxytoca, Enterobacter cowanii et Klebsiella oxytoca, respectivement. Bien qu'on ait rapporté précédemment qu'Enterobacter sp. causait la flétrissure chez nombre de plantes, cet ouvrage expose pour la première fois la susceptibilité de la plupart des hôtes liés a ` R. solanacearum a ` la flétrissure causée par Enterobacter et d'autres bactéries de la famille des Enterobacteriaceae. [Traduit par la Rédaction]

Herein we present a novel and facile approach to effectively synthesize and stabilize copper nanoparticles (CuNPs) using the sugars dextrose, dextrin and β-cyclodextrin. This approach adopts the fundamental principles of 'green chemistry' by usage of nontoxic, renewable chemicals and use of ambient temperature, normal pH and other mild conditions. This work shows that the amphiphilicity presented by the sugars determines the CuNP characteristics. One very important aspect of this work is that these CuNPs show significant antifungal activity towards a potent rice pathogen whose action is wide spread and difficult to control. Thus this work provides a biocompatible method to arrest the growth of a potent rice pathogen. This has widespread implications in areas where rice is the main food crop.

The wild mushroom Coprinosis sp., was collected from local forest and water soluble fraction of the polysaccharide was extracted from the fruiting body. The polysaccharide (CPSS) was partially purified by dialysis. Biochemical estimation of crude extract shows that it contained 90.7% polysaccharides, 8.92% phenolics and 0.28% protein. FTIR spectroscopy further confirmed the presence of polysaccharides. HPLC analysis of CPSS indicated that glucose, galactose and xylose comprised monosaccharide units. Total antioxidant, total reducing power, nitric oxide scavenging and DPPH assay confirmed antioxidant property of CPSS and it was found to work in a dose dependent manner. DCFDA stained images of lung cancer line A549 showed that CPSS was able to reduce intracellular ROS in the cells. Cytotoxicity of CPSS was observed on A549 and L132 cell. It showed that CPSS had potential antitumor activity and it was specific to cancer cells only. Hochest and PI staining indicated the induction of apo...

Alternaria is a plant pathogenic fungus with a wide host range and causes disease in different types of plant. In the present study, eleven Alternaria isolates were collected from infected samples of different host plant belonging to diverse families. Identification and study of diversity study was done based on the morphological features of the isolates i.e., colony characteristics size, septation and beak length of conidia. Genetical variability among the isolates was carried out by using three RAPD primers. All isolates were identified as belonging to the genus Alternaria. The diversity analysis showed that seven of the isolates were different from each. However, TD7 and TD2 resembled in their morphological as well as genetical characters, similarly TD17 and TD12 were also found similar. No significant relationship could be established between host plant infected and pathogen morphological or genetics. It was however apparent that Alternaria sp. may be morphologically similar but...