Role of plastids and mitochondria in the early development of seedlings in dark growth conditions.

Establishment of the seedlings is a crucial stage of the plant life cycle. The success of this process is essential for the growth of the mature plant. In Nature, when seeds germinate under the soil, seedlings follow a dark-specific program called skotomorphogenesis, which is characterized by small, non-green cotyledons, long hypocotyl, and an apical hook-protecting meristematic cells. These developmental structures are required for the seedlings to emerge quickly and safely through the soil and gain autotrophy before the complete depletion of seed resources. Due to the lack of photosynthesis during this period, the seed nutrient stocks are the primary energy source for seedling development. The energy is provided by the bioenergetic organelles, mitochondria, and etioplast (plastid in the dark), to the cell in the form of ATP through mitochondrial respiration and etio-respiration processes, respectively. Recent studies suggest that the limitation of the plastidial or mitochondrial gene expression induces a drastic reprogramming of the seedling morphology in the dark. Here, we discuss the dark signaling mechanisms involved during a regular skotomorphogenesis and how the dysfunction of the bioenergetic organelles is perceived by the nucleus leading to developmental changes. We also describe the probable involvement of several plastid retrograde pathways and the interconnection between plastid and mitochondria during seedling development. Understanding the integration mechanisms of organellar signals in the developmental program of seedlings can be utilized in the future for better emergence of crops through the soil.

Limiting etioplast gene expression induces apical hook twisting during skotomorphogenesis of Arabidopsis seedlings.

When covered by a layer of soil, seedling development follows a dark-specific program (skotomorphogenesis). In the dark, seedlings consist of small, non-green cotyledons, a long hypocotyl, and an apical hook to protect meristematic cells. We recently highlighted the role played by mitochondria in the high energy-consuming reprogramming of Arabidopsis skotomorphogenesis. Here, the role played by plastids, another energy-supplying organelle, in skotomorphogenesis is investigated. This study was conducted in dark conditions to exclude light signals so as to better focus on those produced by plastids. It was found that limitation of plastid gene expression (PGE) induced an exaggerated apical hook bending. Inhibition of PGE was obtained at the levels of transcription and translation using the antibiotics rifampicin (RIF) and spectinomycin, respectively, as well as plastid RPOTp RNA polymerase mutants. RIF-treated seedlings also showed expression induction of marker nuclear genes for mitochondrial stress, perturbation of mitochondrial metabolism, increased ROS levels, and an augmented capacity of oxygen consumption by mitochondrial alternative oxidases (AOXs). AOXs act to prevent overreduction of the mitochondrial electron transport chain. Previously, we reported that AOX1A, the main AOX isoform, is a key component in the developmental response to mitochondrial respiration deficiency. In this work, we suggest the involvement of AOX1A in the response to PGE dysfunction and propose the importance of signaling between plastids and mitochondria. Finally, it was found that seedling architecture reprogramming in response to RIF was independent of canonical organelle retrograde pathways and the ethylene signaling pathway.

Whole-Genome Sequencing of Klebsiella pneumoniae BASUSDALSc45PDB48, a Unique Strain Capable of Growing in Pesticide-Containing Medium, Isolated from Soil in Bangladesh.

We report the draft genome sequence of Klebsiella pneumoniae strain BASUSDALSc45PDB48, isolated from pesticide-contaminated soil; this strain showed the ability to grow in a medium with cypermethrin as the only carbon source. The genome assembly comprised 5,249,704 bp, with 128.17 Ns per 100 kbp, an N50 value of 5,035,968 bp, a GC content of 57.57%, and 5,349 annotated genes.

Diesel degradation efficiency of Enterobacter sp., Acinetobacter sp., and Cedecea sp. isolated from petroleum waste dumping site: a bioremediation view point.

Bioremediation through biodegradation is applied for cleaning up several environmental pollutions including petroleum oil spill containing petrol, diesel, mobil, kerosene, lubricating, etc. which have devastated several endangered terrestrial and aquatic ecosystems. Therefore, the current research was aimed to isolate and identify diesel degrading bacteria from the petroleum waste dumping site and determined their degrading efficiency. The bacterial strains were isolated through a minimum salt medium supplemented with 2% diesel as the sole carbon source. The bacteria were identified by morphological, biochemical characterization, and 16S rRNA gene sequencing. The optimized growth pattern was evaluated by utilization of a wide range of temperatures (25, 30, 35, and 40 °C) and pH (5,6,7 and 8) as well as different concentrations of diesel (2, 3, 5and 7%). Finally, the degradation rate was determined by measuring the residual diesel after 7, 14, and 21 days of incubation. The study isolated Enterobacter ludwigii, Enterobacter mori, Acinetobacter baumannii, and Cedecea davisae where all are gram-negative rod-shaped bacilli. All the bacterial strains utilized the diesel at their best at 30 °C and pH 7, among them, A. baumannii and C. davisae exhibited the best degrading efficiency at all applied concentrations. Finally, the determination of degradation rate (%) through gravimetrical analysis has confirmed the potency of A. Baumannii and C. davisae where the degradation rate was around 61 and 52% respectively after 21 days of incubation period with 10% diesel. The study concludes that all of those isolated bacterial consortiums, especially A. baumannii and C. davisae could be allocated as active agents used for bioremediation to detoxify the diesel-containing contaminated sites in a cost-effective and eco-friendly way.

Coding-Complete Genome Sequences of Three SARS-CoV-2 Strains from Bangladesh.

We report the sequencing of three severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes from Bangladesh. We have identified a unique mutation (NSP2_V480I) in one of the sequenced genomes (isolate hCoV-19/Bangladesh/BCSIR-NILMRC-006/2020) compared to the sequences available in the Global Initiative on Sharing All Influenza Data (GISAID) database. The data from this analysis will contribute to advancing our understanding of the epidemiology of SARS-CoV-2 in Bangladesh as well as worldwide at the molecular level and will identify potential new targets for interventions.

Arbuscular mycorrhizal fungi mitigate Fe deficiency symptoms in sorghum through phytosiderophore-mediated Fe mobilization and restoration of redox status.

Sustainable management of iron (Fe) deficiency through the microbial association is highly desirable to ensure crop yield. This study elucidates whether and how arbuscular mycorrhizal fungi (AMF) ameliorate Fe deficiency symptoms in sorghum. AMF inoculation showed a significant improvement in plant biomass, chlorophyll score, Fv/Fm (quantum efficiency of photosystem II), and Pi_ABS (photosynthesis performance index), suggesting its potentiality to diminish Fe deficiency symptoms in sorghum. This AMF-driven prevention of Fe deficiency was further supported by the improvement of biochemical stress indicators, such as cell death, electrolyte leakage, hydrogen peroxide, and superoxide anion. In this study, AMF showed a significant increase in phytosiderophore (PS) release as well as Fe and S concentrations in sorghum under Fe deficiency. Quantitative real-time PCR analysis demonstrated the consistent upregulation of SbDMAS2 (deoxymugineic acid synthase 2), SbNAS2 (nicotianamine synthase 2), and SbYS1 (Fe-phytosiderophore transporter yellow stripe) in roots due to AMF with Fe deficiency. It suggests that the enhancement of Fe due to AMF is related to the mobilization of Fe(III)-PS in the rhizosphere supported by the long-distance transport of Fe by SbYS1 transporter in sorghum. Our study further showed that the elevation of S mainly in the presence of AMF possibly enhances the S-containing antioxidant metabolites (Met, Cys, and GSH) as well as enzymes (CAT, SOD, and GR) to counteract H2O2 and O2- for the restoration of redox status in Fe-deprived sorghum. Moreover, S possibly participates in Strategy II responses revealing its crucial role as a signaling molecule for Fe homeostasis in sorghum.

In-vivo antiproliferative activity of Morus latifolia leaf and bark extracts against Ehrlich's ascites carcinoma.

Cancer is the second death causing disease all over the world and until today 100 different types of cancer have been identified whose treatment methods consist of serious side effects on human body. To reduce the frequency of adverse effects of cancer treatment, nowadays plant derived natural components are getting priority. The plant Morus latifolia is widely available in northern part of Bangladesh. The earlier researches suggested that popular varieties of some Morus sp. like Morus alba, Morus indica etc. have good anti-proliferative activity. Hence, this study was designed to evaluate the anti-proliferative activity of leaf and bark extracts of M. latifolia against Ehrlich's ascites carcinoma (EAC) in vivo. The leaf and bark extracts of M. latifolia were used in several bioassays including Brine shrimp lethality test, hemagglutination activity test, antioxidant activity test, and cell growth inhibition test. Besides, fluorescence microscopy was performed to study apoptotic features in EAC cells, and molecular analysis like real-time PCR were also conducted. The results of Brine shrimp lethality test, hemagglutination activity test, and antioxidant activity assay supported the cell growth inhibition capability of leaf and bark extracts which was confirmed by in vivo cell growth inhibition bioassay. Moreover, the experimental extracts were able to induce cell apoptotis through altering the expression pattern of Bcl-2 and Bax genes. All of the results of this study suggest that several noble compounds are present in M. latifolia plant extracts which are capable for healing cancer cells.

Mechanisms and Signaling Associated with LPDBD Plasma Mediated Growth Improvement in Wheat.

This study investigates the effect and mechanisms of low pressure dielectric barrier discharge (LPDBD) produced with Ar/O2 and Ar/Air technique causing biological stimulation leading to improved germination and growth in wheat. Both plasma treatments caused rougher and chapped seed surface along with noticeable improvement in seed germination in wheat. Beside this, seed H2O2 concentration significantly increased compared to controls subjected to Ar/O2 and Ar/Air while this phenomenon was more pronounced due to Ar/Air plasma. Analysis of plants grown from the plasma treated seeds showed significant improvement in shoot characteristics, iron concentration, total soluble protein and sugar concentration in comparison with the controls more efficiently due to Ar/O2 plasma than that of Ar/Air. Further, none of the plasma treatments caused membrane damage or cell death in root and shoot of wheat. Interestingly, Ar/O2 treated plants showed a significant increase (2-fold) of H2O2 compared to controls in both root and shoot, while Ar/Air plasma caused no changes in H2O2. This phenomenon was supported by the biochemical and molecular evidence of SOD, APX and CAT in wheat plants. Plants derived from Ar/O2 treated seeds demonstrated a significant increase in SOD activity and TaSOD expression in roots of wheat, while APX and CAT activities along with TaCAT and TaAPX expression showed no significant changes. In contrast, Ar/Air plasma caused a significant increase only in APX activity in the shoot. This suggests that Ar/O2 plasma caused a slight induction in H2O2 accumulation without triggering the H2O2 scavengers (APX and CAT) and thus, efficiency affect growth and development in wheat plants. Further, grafting of control and Ar/O2 treated plants showed a significant increase in shoot biomass and H2O2 concentration in grafts having Ar/O2 rootstock regardless of the type scion attached to it. It indicates that signal driving Ar/O2 plasma mediated growth improvement in wheat is possibly originated in roots. Taken together, this paper delivers new insight into the mechanistic basis for growth improvement by LPDBD technique.