Optimization of callus induction and callus multiplication in rice (Oryza sativa L.) landraces

In vitro selection for abiotic stress tolerance in rice is one of the most common and reliable way for improvement of selection efficiency, but this requires standardized protocols

Effect of combination of light and drought stress on physiology and oxidative metabolism of rice plants

The realized productivity of crop plants is generally lower than the potential productivity due to the influence of one or more external stresses (biotic and abiotic). Simultaneous occurrence of combination of abiotic stresses, which is more common under field condition, results in compounded effect on functional processes. Main focus of the present work is the combined effect of drought and light (irradiance) on rice plants. Potted seedlings of four selected rice lines (viz., IR36, N22, CRD40 and Bhootmuri) were exposed to three different levels of drought stress (50%, 25%, 12.5% of water) along with control (100%) in combination with three different light intensities (high, medium and low) during experimental period. After 7 days of stress, plant height and relative water content (RWC) were relatively low while root length increased with increasing water stress level and light intensity. Protein content increased with increasing water stress and light intensity, while chlorophyll level was higher at higher light intensities. Malondialdehyde (MDA) content, indicative of lipid peroxidation, increased with water stress only at high light intensities. Superoxide dismutase (SOD), peroxidase (POX) and ascorbate peroxidase (APX) activities increased with combined drought and light stress level, whereas catalase (CAT) activity was higher at higher light intensities. On the other hand, superoxide (O2.-) production, but not hydrogen peroxide (H2O2) production was higher with increasing water stress and light intensity. It appears that light-induced ROS (O2.-) production under drought condition provoked oxidative stress, though a potential mechanism of tolerance was apparent through antioxidant system

Growth promoting properties of Mycobacterium and Bacillus on rice plants under induced drought

Management of drought stress through application of plant growth promoting rhizobacteria (PGPR) is now considered as an effective strategy in the present scenario of altered environmental conditions of the world. The aims and objectives of the present investigation was isolation, characterization and identification of some potential microbial resources (PGPR) from drought-affected upland rice fields of South Bengal followed by experimentation on the effect of isolated PGPR on drought induced rice seedlings. Selected isolates were isolated from rice field rhizospheric soils and tested for their PGPR activity, through phosphate solubilization, nitrogen fixation, IAA production and ACC deaminase activity. Then, the selected isolates were identified through 16S rDNA sequencing and phylogenetic analysis. Among the screened isolates two (isolate 1 and isolate 6) showing plant growth promoting traits, was applied on studied germplasm (IR64) to find out the influence of the applied organisms on rice growth and development under induced drought. Both organisms showed a positive influence (through increase in germination percentage, root growth, shoot growth, fresh weight and dry weight) on the studied rice growth and development under induced drought. Isolate 1 and 6 identified as species of Mycobacterium sp and Bacillus sp respectively through molecular taxonomy. Hence, these two isolates are expected to alleviate drought stress in the rice field for their nature of plant growth promotion under drought stress

Physiological alterations of Salvinia natans L. exposed to aluminium stress and its interaction with polyamine

In the present Investigation Salvinia natans L exposed to increasing concentration of Al stress and its interaction with polyamine was discussed. Among the physiological attributes Glutathione-S-transferase, glutathione peroxidase activities were up regulated against control. At transcript level glutathione peroxidase was also shown by over-expressed manner to support the lyses of peroxide. However, the application of Put had minimized these activities with same way to establish the role of polyamine under metal stress. In secondary metabolites synthetic pathway phenyl alanine ammonia lyase recorded a steady increase although the concentration of Al. Not only a single fraction of polyamine was responsible under Al stress but also pool of conjugated polyamine was up regulated. In oxidation of polyamine the activity of diamine oxidase (DAO) was more under metal stress to induce accumulation H2O2. In compensation for cellular depletion of reduced glutathione, dihydro ascorbate reductase activity was up regulated in plant under stress. At cellular level plants were distinctly marked with variations in heat shock proteins and established as a possible biomarker for Al toxicity. The study possibly established the affectivity in bio-monitoring of Al in field condition with exercise cellular responses of Salvinia plants

Cellular response of oxidative stress when sub1A QTL of rice receives water deficit stress

In this experiment, sub1A quantitative trait loci (sub1A QTL) of rice were evaluated for dehydration responses through different aspects of cellular responses. Through variations of dehydration exposure, rice seedlings recorded a significant increase in superoxide (O2.-) and hydrogen peroxide (H2O2), the former by 1.80 fold and the latter by 2.10 fold. Nicotinamide adenine dinucleotide phosphate oxidase activity fairly correlated with lipid peroxidation (r = 1.96). Both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) had similar IC50 values over the control at p ? 0.05. Reducing power of the extract had 1.31 fold increase. The antioxidant moieties like total phenolics and flavonoids were 1.04 and 1.23 fold upregulated under stress. On the other hand anthocyanin and glutathione (GSH) did not vary much under stress except at maximum duration of stress. Superoxide dismutase (SOD) was initially stable but maximized at 8 days by 1.30 fold increase. On the contrary, guaiacol peroxidase (GPX) was seen to be downregulated by 40.94% all through the days of stress. Catalase (CAT) activity followed a similar trend, but was not significant as compared to control

Global transcriptome analysis in rice (Oryza sativa. L) through RNASeq analysis

The NCBI-SRA database, one of the most significant and effective public repository of short reads generated through high throughput NGS analysis is at present a valuable global resource for study of raw transcripts, are being used to validate experimental results, determine genetic variants has open up a new avenues of Bioinformatics research. In this present work a publicly available transcriptome sequence data (BioProject: PRJNA272732) that was conducted on leaf tissue of rice mutant for heat stress transcription factor (OsHsfA2e) under well-watered and drought stressed conditions at vegetative stage has been used to study the differential gene expression through recent bioinformatics pipelines of RNAseq analysis. The sequenced reads were processed through an RNASeq analysis pipeline based on negative binomial algorithms and visualized through R based package (Deseq). The transcripts showing significant differential gene expression were analyzed further for gene ontology and pathway enrichment analysis. Of the different pipelines the most common one is the Tuxedo pipeline where the reads from two or more different conditions are first mapped to the ref. genome to generate assembled transfrags for each replicates using TopHat and Cufflinks respectively, followed by quantification of merged annotation by CuffDiff. Finally, the generated files were indexed and visualized with CummeRbund to facilitate exploration of genes identified by CuffDiff as differentially expressed, spliced, or transcriptionally regulated genes. FPKM, fragments per kilobase of transcript per million fragments mapped. In an alternative approach the reads that fall into annotated genes were used to generate read counts for each different condition. The counts generated were analyzed through an R based statistical analysis with two dedicated packages (DESeq and edgeR). All the different analysis that was carried out insilico of the mention BioProject will be presented in this upcoming conference

Varied shoot growth in rice plants across different developmental stages under induced flooding

All the modern high yielding rice varieties precariously respond to flooding, although a number of landraces are tolerant to wide range of flooding with penalty of low yield. Stage-specific flood tolerance experiment was performed at three different conditions for three different growth stages from germination to vegetative stage for five such selected landraces, along with a flood-resistant quiescent variety (FR13A), a sensitive line (IR42), an improved cultivar (Swarna) and one Sub1 loci introgressed improved line (Swarna-Sub1). Different morpho-physiological traits at each stage were observed and genotypes were evaluated by these quantifiable traits to understand their underwater performance. All the studied landraces represented strong seed germination and faster coleoptile elongation than FR13A, Swarna and Swarna-Sub1 under water. At early seedling stage var. Kumrogarh embraced with highest number of seedlings with leaves and extended greater leaf portion above the water. Shoot elongation associated with internodal and petiole/blade elongation and well developed aerenchyma tissue facilitated vegetative tissues to survive. In this stage, Kumrogarh had highest plant height but Bakui had highest internodal length which indicated that kumrogarh might have the greater leaf sheath or blade elongation up to day 21 and also smaller increase (%) in air cavity formation at day 21 which made the stem to be upright devoid of lodging. All these results indicated that the studied landraces are the potential resources for submergence avoiding response for all the stages and should be elaborately investigated for future breeding programme. The rice line kumrogarh may be one of the potent traditional rice which can withstand all sorts of submergence by virtue of all the stage-specific attributes under submergence stress

Physiological, biochemical, and molecular screening of selected upland rice (Oryza sativa L.) lines from eastern India

Abstract Background Ten improved upland rice lines presently grown in dry upland rice field of Jharkhand, Odisha, and Bengal, the three most significant rice yielding states of eastern India, were screened under varying induced water stress to reveal their physiological and biochemical performance followed by rice microsatellite-based genotyping and detection of SNPs for a selected genetic loci (OsLEA3) associated with drought responses in higher plants. Results For physiological screening changes in plant height and external appearance of mature plant particularly greenish appearance were considered. Quantitative estimation of six biochemical compounds (chlorophyll, carotenoids, catalase, peroxidase, ascorbate peroxidase), commonly associated with normal physiological processes of plants, showed variable response under induced water stress. Variety Vandana and CRdhan 40 were identified to be the most potent drought-avoiding genotypes, whereas variety Sneha and Kalinga III showed least degree of drought tolerance for the studied screening parameters under drought. In post stressed period, both the variety Vandana and CRdhan 40 showed best performance to recover by virtue of regular water supply for a month tenure. In SSR-based genotyping, RM3825 and RM242 showed highest degree of polymorphism, whereas RM321 was monomorphic across the selected rice lines. Genomic DNA of only four lines (Vandana, Anjali, CR dhan 40, and Sahabhagidhan) were amplified with the primer pairs designed from OsLEA3 gene sequence which resulted three distinct allelic forms. Vandana and CR Dhan 40 shared a common allele of mol. wt. 1173 bp size, whereas other two allelic forms were detected by Anjali and Sahbhagi of mol. wt. 1210 bp and 1036 bp respectively. A total number of 23 SNPs were detected for amplified sequence of OsLEA3 gene sequence in CR Dhan 40 of which 12 were transitions and 11 were transversions. Conclusion From this study, it could be concluded that var. CR Dhan 40, Vandana, and Sahabhagidhan performed better, both physiologically and biochemically under induced drought stress

Genetic potentiality of indigenous rice genotypes from Eastern India with reference to submergence tolerance and deepwater traits

Submergence tolerance in rice varieties is crucial for maintaining stable yields in low land areas, where recurrence of flooding is a constant phenomenon during monsoon. We have conducted detailed physiological and genotyping studies of 27 rice genotypes and one wild rice relative, popularly grown in low land areas of the two major rice growing states of eastern India, West Bengal and Odisha with a focus on submergence tolerance traits and Sub1 loci. We found that these genotypes show varying degree (50–100%) survival rate during post submergence recovery period, and high degree of polymorphism in the Sub1 linked rice microsatellite loci RM219 and RM7175. Detailed allelic diversity study of Sub1A loci suggests that rice varieties IR42, Panibhasha, Khoda and Kalaputia share a common allele that is different from FR13A, Keralasundari, Bhashakalmi, Kumrogore. Two other genotypes Meghi and Khoda shares both alleles of Sub1A loci (present in IR42 and FR13A groups) in addition to a new variant. Detailed sequence analysis of the amplified product for the Sub1A loci from these genotypes showed several single nucleotide changes with respect to reference Oryza sativa Sub1A loci (DQ011598). Three rice genotypes (Meghi, Bhashakalmi and Keralasundari) showed beneficial properties in relation to induced submergence stress and can be considered as valuable genetic source in context of utilization of natural rice genetic resources in breeding program for submergence tolerance

An exploratory study on allelic diversity among rice and its wild species as well as relatives with simple sequence repeat and inter simple sequence repeat markers

357-362Genomic information of crop plants is a pre-requisite for the enrichment and management of the crop’s genetic resources. Rice has a number of wild species and wild relatives, which harbour a good number of agronomically important genes that can be incorporated into the cultivated rice. In the present work, a wild rice (Oryza rufipogon Griff.) and a wild rice relative, Porteresia coarctata (Roxb.) Tateoka (syn. O. coarctata Roxb.), were genotyped with trait (osmotic stress tolerance) linked 29 SSR and 22 ISSR markers, distributed throughout the rice genome. For exploring the comparative allelic diversity (in the form of difference in mol wt of amplified products for a particular SSR or ISSR locus), two marker based panels were constructed considering cultivated rice (O. sativa L.) as the reference genotype. Among the studied SSR markers, the maximum allelic variation was found with RM10773, which showed the maximum difference (370.25 bp) between O. sativa and O. rufipogon, and also with RM10864 that showed a difference of 194.47 bp between O. sativa and P. coarctata. For ISSR loci, the maximum difference (300.73 bp) between O. sativa and O. rufipogon was shown by PR36, and the maximum difference (451.66 bp) between O. sativa and P. coartata was shown by PR29. The genotypic profiles prepared in the present investigation may be used for identification of the corresponding genotypes and in marker assisted hybridization programmes