Population Structure,Diversity and Trait Association Analysis in Rice (Oryza sativa L.) Germplasm for Early Seedling Vigor (ESV) Using Trait Linked SSR Markers

Early seedling vigor (ESV) is the essential trait for direct seeded rice to dominate and smother the weed growth. In this regard, 629 rice genotypes were studied for their morphological and physiological responses in the field under direct seeded aerobic situation on 14^th, 28^th and 56^th days after sowing (DAS). It was determined that the early observations taken on 14^th and 28^th DAS were reliable estimators to study ESV as compared to56^th DAS. Further, 96 were selected from 629 genotypes by principal component (PCA) and discriminate function analyses. The selected genotypes were subjected to decipher the pattern of genetic diversity in terms of both phenotypic and genotypic by using ESV QTL linked simple sequence repeat (SSR) markers. To assess the genetic structure, model and distance based approaches were used. Genotyping of 96 rice lines using 39 polymorphic SSRs produced a total of 128 alleles with the phenotypic information content (PIC) value of 0.24. The model based population structure approach grouped the accession into two distinct populations, whereas unrooted tree grouped the genotypes into three clusters. Both model based and structure based approach had clearly distinguished the early vigor genotypes from non-early vigor genotypes. Association analysis revealed that 16 and 10 SSRs showed significant association with ESV traits by general linear model (GLM) and mixed linear model (MLM) approaches respectively. Marker alleles on chromosome 2 were associated with shoot dry weight on 28 DAS, vigor index on 14 and 28 DAS. Improvement in the rate of seedling growth will be useful for identifying rice genotypes acquiescent to direct seeded conditions through marker-assisted selection.     

Efficient TDZ-induced regeneration from capitulum explants of Gerbera jamesonii Bolus ex Hooker F. - an ornamental plant with high aesthetic value

Gerbera jamesonii Bolus ex Hooker F. (Asteraceae), a most prominent ornamental plant ranking fifth in the world cut flower market has gained huge demand across the globe for its high aesthetic value. In the present study, an efficient plant regeneration protocol was developed using capitulum explants from the field grown mature plants of G. jamesonii. A successful surface sterilization procedure was established using a series of sterilants without affecting explant regenerability. The culture of capitulum explants on Pre-culture Induction Medium [(PIM), Murashige and Skoog (MS) medium fortified with 0.5?mg/L thidiazuron (TDZ) in combination with low levels of auxins] for a period of 2 weeks in dark conditions was crucial for inducing morphogenetic response. Upon transfer onto Shoot Regeneration Medium [(SRM), MS +4.0?mg/L 6-benzyladenine (BA) and 0.2?mg/L NAA], explants has significantly produced highest number of shoots (16?±?0.33). Incubation for 18–21?days on Shoot Multiplication and Elongation Medium [(SMEM), MS +2.0?mg/L BA +0.2?mg/L NAA] resulted in the highest number of multiple shoots (22.00?±?0.93) with increased mean shoot length (3.49?±?0.08). In vitro elongated shoots were rooted (95%) on ½ MS +1.0?mg/L indole-3-acetic acid (IAA) within 10–12?days and fully rooted plants were transferred to poly-house for hardening with 90% survival rate.     

A rapid and efficient method for in vitro shoot organogenesis and production of transgenic Bacopa monnieri L. mediated by Agrobacterium tumefaciens

Efficient shoot regeneration and Agrobacterium-mediated genetic transformation systems were developed for Bacopa monnieri L. (Scrophulariaceae), a plant well known for its medicinal properties. Leaf explants were cultured on Murashige and Skoog (MS) medium with different concentrations of 6-benzylaminopurine (BAP), and in combination with either indole-3-acetic acid (IAA) or napthalene-3-acetic acid. A combination of BAP (17.80 μM) and IAA (2.28 μM) maximized shoot initiation (85.2 ± 2.43) with greatest shoot length (2.8 ± 0.22), and was obtained directly from leaf explants without an intervening callus phase. Leaf segments from in vitro grown plants were co-cultivated with Agrobacterium tumefaciens LBA4404 harboring pCAMBIA1301 with ?-glucuronidase (uidA) and hygromycin phosphotransferase (hpt) genes. The co-cultivated explants were transferred to selective shoot induction and elongation medium. The elongated hygromycin-resistant shoots were subsequently rooted on MS medium supplemented with 4.9 μM indole-3-butyric acid and 25 mg/l hygromycin (SSRM). Successful transformation was confirmed by monitoring histochemical GUS activity during shoot elongation and PCR analyses using uidA- and hpt-specific primers. Integration of hpt into the genome of transgenic plants was also verified by Southern blot analysis. The highest transformation efficiency achieved was 70.6%, with an average of 10.4 ± 0.15 transgenic plantlets per explant using the present transformation system. Therefore, these highly efficient and rapid regeneration and transformation systems create significant potential for engineering of B. monnieri with a view to detailed biomolecular analyses or for further enhancement of its medicinal properties.     

Prevalence of GB virus type C in urban Americans infected with human immunodeficiency virus type 1

Human T-lymphotropic virus type 1 (HTLV-1) and HTLV-2 were among the first human retroviruses discovered in the early 1980's. The International Retrovirology Association is an organized effort that fostered the efforts of scientists and clinicians to form interdisciplinary groups to study this group of retroviruses and their related diseases. The Association promotes excellent science, patient education, and fosters the training of young scientists to promote "bench-to-bedside" research. The International Conference on Human Retrovirology: HTLV and Related Viruses sponsored by the Association supports clinicians and researchers in the exchange of research findings and stimulation of new research directions. This years conference will be held from June 22 to 25, in Montego Bay, Jamaica http://www.htlvconference.org.jm/. Since its inception in 1988, these conferences have provided a highly interactive forum for the global community of HTLV scientists. This is of particular importance as HTLV research enters its third decade and a new generation of scientists takes over this important work. Many of the scientists attending the meeting will be from developing countries where HTLV is endemic, consistent with the history of international collaborations that have characterized HTLV research. The International Conference on Human Retrovirology provides a unique opportunity for researchers of all disciplines interested in HTLV infections to meet their peers and to address the questions facing clinicians and scientists who study retroviruses, like HTLV.     

Flavanoids from Caesalpinia pulcherrima

Two new flavanoids, 5,7-dimethoxy-3',4'-methylenedioxyflavanone and isobonducellin along with 2'-hydroxy-2,3,4',6'-tetramethoxychalcone, 5,7-dimethoxyflavone and bonducellin were isolated from the aerial parts of Caesalpinia pulcherrima. The structures of the compounds were settled mainly by interpretation of their 1D and 2D NMR spectra. Isobonducellin was found to be a homoisoflavanoid containing a cis (Z)-double bond. Antimicrobial activity of the new compounds was evaluated.     

Biolistic transformation of <Emphasis Type="Italic">Scoparia dulcis</Emphasis> L.

Here, we report for the first time, the optimized conditions for microprojectile bombardment-mediated genetic transformation in Vassourinha (Scoparia dulcis L.), a Plantaginaceae medicinal plant species. Transformation was achieved by bombardment of axenic leaf segments with Binary vector pBI121 harbouring β-glucuronidase gene (GUS) as a reporter and neomycin phosphotransferase II gene (npt II) as a selectable marker. The influence of physical parameters viz., acceleration pressure, flight distance, gap width & macroprojectile travel distance of particle gun on frequency of transient GUS and stable (survival of putative transformants) expressions have been investigated. Biolistic delivery of the pBI121 yielded the best (80.0 %) transient expression of GUS gene bombarded at a flight distance of 6 cm and rupture disc pressure/acceleration pressure of 650 psi. Highest stable expression of 52.0 % was noticed in putative transformants on RMBI-K medium. Integration of GUS and npt II genes in the nuclear genome was confirmed through primer specific PCR. DNA blot analysis showed more than one transgene copy in the transformed plantlet genomes. The present study may be used for metabolic engineering and production of biopharmaceuticals by transplastomic technology in this valuable medicinal plant.     

Esterase polymorphisms in muscle and brain of four fresh water fishes belonging to the family Cyprinidae

Esterase polymorphism in muscle and brain tissues of four species of freshwater fishes belonging to the family cyprinidae are examined using polyacrylamide gel electrophoresis. The enzymes are classified according to their substrate specificity and inhibitor sensitivity. Distribution of six classes of esterases; viz. carboxyl, acetyl, aryl, choline, Esdp and ER-esterases in the two tissues of the four species is reported.     

Highly efficient production of transgenic Scoparia dulcis L. mediated by Agrobacterium tumefaciens: plant regeneration via shoot organogenesis

Efficient Agrobacterium-mediated genetic transformation of Scoparia dulcis L. was developed using Agrobacterium tumefaciens strain LBA4404 harboring the binary vector pCAMBIA1301 with β-glucuronidase (GUS) (uidA) and hygromycin phosphotransferase (hpt) genes. Two-day precultured leaf segments of in vitro shoot culture were found to be suitable for cocultivation with the Agrobacterium strain, and acetosyringone was able to promote the transformation process. After selection on shoot organogenesis medium with appropriate concentrations of hygromycin and carbenicillin, adventitious shoots were developed on elongation medium by twice subculturing under the same selection scheme. The elongated hygromycin-resistant shoots were subsequently rooted on the MS medium supplemented with 1 mg l⁻¹ indole-3-butyric acid and 15 mg l⁻¹ hygromycin. Successful transformation was confirmed by PCR analysis using uidA- and hpt-specific primers and monitored by histochemical assay for β-GUS activity during shoot organogenesis. Integration of hpt gene into the genome of transgenic plants was also verified by Southern blot analysis. High transformation efficiency at a rate of 54.6% with an average of 3.9 ± 0.39 transgenic plantlets per explant was achieved in the present transformation system. It took only 2–3 months from seed germination to positive transformants transplanted to soil. Therefore, an efficient and fast genetic transformation system was developed for S. dulcis using an Agrobacterium-mediated approach and plant regeneration via shoot organogenesis, which provides a useful platform for future genetic engineering studies in this medicinally important plant.