Genetic diversity and marker trait association for yellow mosaic virus disease in green gram, Vigna radiata (L.) Wilczek

Yellow mosaic virus (YMV) disease is known to cause severe damage in green gram in terms of yield loss. As the resistance is often governed by recessive genes, introgression of such resistance faces some difficulty. DNA molecular markers are reported to be effective in this process. However, validation of such markers is important. Here, we have made an attempt to validate DNA markers associated with YMV disease resistance gene from a diverse group of 26 green gram genotypes. A total of 19 molecular markers were used to assess the susceptibility or resistance against YMV disease. Results show that among the amplified 31 alleles, 21 were polymorphic, with a mean of 1.1.0 per locus. The polymorphism information content (PIC) values ranged from 0.32 to 0.80. Only five markers exhibited higher PIC value (>6.0) and were revealed to be polymorphic, suggesting its utility in marker assisted selection for breeding YMV resistant genotypes in greengram. Dice dissimilarity coefficient among the genotypes exhibited a range of 0.07 to 1.0 which show a wide genetic variation among the genotypes for YMV tolerance. Neighbor-joining cluster analysis has grouped 26 green gram genotypes into 4 main clusters which revealed the existence of genetic dissimilarities among the genotypes. The genotypes AUGG 6, VBN (Gg) 2 and CO (Gg) 8 carried the positive alleles for YMV disease resistance and the allele for susceptibility were found in the genotypes AUGG 12, AUGG 15, AUGG 17 and AUGG 19. Single marker analysis indicated that there was correlation between the markers and the disease reaction in the field with exceptions. The findings revealed that the SSR markers CEDG180 and YR4 could be used to screen germplasm in order to discriminate the YMV resistant genotypes from the susceptible genotypes in marker assisted selection.

Screening for seedling stage salinity tolerance and comparative transcriptome analysis in Rice (Oryza sativa L.)

Soil salinity is one of the major abiotic stresses which affect crop productivity including rice, Oryza sativa L. Developing salt tolerant varieties gained considerable attention accordingly. Here, we studied salinity tolerance in rice crop. We screened ten rice genotypes for saline tolerance at different concentrations of 0 dSm-1, 2 dSm-1, 4 dSm-1, 6 dSm-1, 8 dSm-1,10 dSm-1, 12 dSm-1 and 14 dSm-1, respectively. Among the ten genotypes studied, CARIDhan-7 tolerated salt stress up to 6dSm-1 of irrigated water. Comparative transcriptome analysis was done with the genotypes by treating with saline water at 0dSm-1 and 6 dSm-1. A total of 1013 genes were differentially expressed under simulated stress conditions. Out of which, 551 genes were upregulated and 462 genes were downregulated. Based on the metabolic pathway analysis, the MAPK signaling pathway, along with the other 9 pathways were found to be enriched in the stressed sample. Nine ion transporter genes, 1potassium channel, 1 protein phosphatase gene, IAA homologs OsIAA9, two ROS scavenging-related genes, and 4 stress regulated genes identified were found to be significantly up-regulated along with some functional proteins previously reported under salt stress. An AP2-like ethylene-responsive transcription factor PLETHORA 2 was found to be downregulated. The results suggested that the CARIDhan-7 genotype undergoes various saline tolerant mechanisms and pathways in response to the stress imposed when compared to non-stressed seedlings.

Combined effect of zinc oxide nano particle incorporated chitosan for better antimicrobial activity towards wound healing

Aim: The aim of the present study was to characterize the zinc oxide nano particle incorporated Chitosan (ZnO-NP-CS) and its antimicrobial activity. Methodology: Zinc oxide nanoparticles (ZnO-NP) were prepared by sol-gel method and Minimum Inhibitory Concentration (MIC), Minimum bactericidal Concentration (MBC) and agar well diffusion method was used for the assessment of antibacterial activity of ZnO-NP and ZnO-NP-CS as well. Results: In UV–spectroscopy, blue shift in wavelength (~365 nm) corresponding to bulk ZnO particles (~385 nm) indicates the nano size. In SEM image, ZnO-NP appeared as nano flake shape and ZnO-NP treated Methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa (PA) bacteria illustrates leakage of intracellular content, fusion and shrinkage of bacteria, respectively. The MIC of ZnO-NP for most of food pathogens were between 0.01 to 0.1mg. Lower MIC was observed for Vibrio cholerae and Listeria monocytogenes; higher MIC was observed for Bacillus cereus and Pseudomonas aeruginosa. In antibiogram assay, the zone of inhibition of ZnO-NP-CS was equal to commercial antibiotics against Multiple Drug Resistant bacteria. Interpretation: The combined effect of ZnO-NP and chitosan is better than the individual component, i.e., around 5–15 mm wider zone of inhibition than chitosan. ZnO-NP-CS can be a suitable alternative for the treatment of wound infected by multiple drug resistant bacteria

In vitro transverse thin cell layer culture in mung bean Vigna radiata (L.) Wilczek

Mung bean [Vigna radiata (L.) Wilczek] is an important grain legume crop. Earlier works on micropropagation protocols for mung bean suffer from genotype dependence, poor reproducibility and insufficient regeneration efficiency. Hence, we made an attempt to develop an efficient protocol for micropropagation of mung bean cv. KM 2 using transverse thin cell layer (tTCL) system. The epicotyl, hypocotyl and nodal tTCL explants were obtained from 5-day-old seedlings and cultured on MS medium with different concentrations of BAP (6-benzylaminopurine), TDZ (Thidiazuron) and kinetin. The maximum frequency (75.25%) of direct shoot initiation and multiplication was achieved from culturing the nodal tTCL explants on MS medium containing 1.0 mg/L BAP. It has been observed that 61.4% of the regenerated shoots successfully elongated and rooted in MS medium containing 1.0 mg/L of IBA (indole-3-butyric acid) after two weeks of culture. The plantlets successfully established under greenhouse conditions with 64 % survival rate. The hardened plants exhibited homogeneity and no morphological variations were detected among the regenerants and the mother plants. The identified regeneration system could be efficiently used in various in vitro manipulation studies in mung bean as well.

Assessment of genetic diversity among sesame (Sesamum indicum L.) germplasm as revealed by RAPD and SSR markers

Sesame (Sesamum indicum L.) is an important crop known for its high-quality edible oil. Molecular markers are useful to explore highly diverse genotypes and relationships among populations for crossbreeding programs. In the present investigation, the genetic fidelity of 9 sesame cultivars of Tamil Nadu was assessed by 10 RAPD (Random Amplified Polymorphic DNA) and SSR (Simple Sequence Repeats) markers. A total of 102 DNA bands were obtained with RAPD primers, of which 46 were polymorphic. SSR primers generated 19 bands, of which 8 were polymorphic. The genetic relationships of nine varieties were inferred using the average linkage method. The cultivars were grouped into 2 clusters from RAPD and 3 clusters from SSR markers. Among the two RAPD clusters, cluster I comprised of TMV 4, TMV 5, TMV 6, TMV 7, SVPR 1, VRI 1, VRI 2, and CO 1 and cluster II comprised of TMV 3 cultivar. In SSR clusters, cluster I consisted of CO 1 and VRI 2, cluster II consisted of TMV 5, TMV 6, TMV 7, VRI 1, and SVPR 1 and cluster III consisted of TMV 3 and TMV 4 cultivars. The experimental results showed that mono-geographical separation of cultivars generally did not result in the greater genetic distance. This study demonstrated that RAPD and SSR markers were appropriate for evaluation of low diversified sesame varieties. Understanding of these characteristics of sesame cultivars in Tamil Nadu will provide a theoretical foundation for further development of variation among the sesame cultivars.

Usefulness of rabbits and mice as experimental laboratory models for Ehrlichia bovis.

Attempts were made to infect mice and immunosuppressed rabbits with Ehrlichia bovis. While evidence of infection could be noticed in rabbits, their identity as E. bovis needs confirmation. Mice appeared to be infected and showed clear inclusions in both blood monocytes and peritoneal macrophages. While symptoms of disease were not observable in rabbits, alopecia, dullness and death were noticed among infected mice. It is concluded that mice are better laboratory models for E. bovis infection; also that infection in mice could be enhanced by immunosuppression.