Rajib Roychowdhury

Profiling of selected indigenous rice (Oryza sativa L.) landraces of Rarh Bengal in relation to osmotic stress tolerance.

A total of ten rare indigenous rice landraces of West Bengal were screened for germination potential and seedling growth under varying concentrations of sodium chloride (NaCl) and polyethylene glycol (PEG) solutions as osmotic stress inducing agents. Among the studied rice landraces Kelas and Bhut Moori showed highest degree of tolerance to induced osmotic stresses. Proline content of the studied lines was also determined. Genetic relationship among the studied rice landraces was assessed with 22 previously reported osmotic stress tolerance linked Simple Sequence Repeat (SSR) markers. The identified allelic variants in form of amplified products size (molecular weight) for each SSR marker were documented to find out allele mining set for the linked markers of the studied genotypes in relation to osmotic stress tolerance. A Microsatellite Panel was constructed for the different allelic forms (size of amplified products) of each used marker. Among 22 SSR markers, ten showed unique alleles in form of single specific amplified product for the studied four genotypes which can be used for varietal identification. Genetic relationship among the studied rice lines was determined and a dendrogram was constructed to reveal their genetic inter-relationship. Polymorphism Information Content (PIC) for each used marker was also calculated for the studied rice lines.

Mutagenesis—A Potential Approach for Crop Improvement

Global environmental dissociative changes are now in steady state. Its negative impacts were gradually imposed on a wide range of crops and thus crop improvement was hindered as well. Given this challenge, existing and new, appropriate technologies need to be integrated for global crop improvement. Among the different present approaches, mutagenesis and mutation breeding and the isolation of improved or novel phenotypes in conjunction with conventional breeding programmes can result in mutant varieties endowed with new and desirable variation of agrometrical traits. Induced mutations and its related technologies play very well in this ground and this overall strategy helps to trace the crop genetic diversity along with its biodiversity maintenance. Such induced mutagenesis, a crucial step in crop improvement programme, is now successful in application due to the advancement and incorporation of large-scale selection techniques, micropropagation and other in vitro culture methods, molecular biology tools and techniques in modern crop breeding performance. Time to time, different mutation techniques and their application processes are changing significantly; in this perspective, insertional mutagenesis and retrotransposons are taking more supports for mutational tagging and new mutation generation. For details investigation on plant structure and function, mutagenic agents and their precise role are much essential as it can produce mutants with some phenotypic changes. Functional genomics studies make the ultimatum platform on this field of study where few crop plants were used for mutational experimentation on some prime agronomic traits till now. This is a prerequisite step and is applying on diverse crop for further improvement. High throughput DNA technologies for mutation screening such as TILLING (Targeting Induced Limited Lesions IN Genomes), high-resolution melt analysis (HRM) , ECOTILLING etc. are the key techniques and resources in molecular mutation breeding. Molecular mutation breeding will significantly increase both the efficiency and efficacy of mutation techniques in crop breeding. Such modern and classical technologies are using for the development of mutation induction with the objective of using a set of globally important crops to validate identified relevant novel techniques and build these into modular pipelines to serve as technology packages for induced crop mutations. Thus, mutation assisted plant breeding will play a crucial role in the generation of ‘designer crop varieties’ to address the uncertainties of global climate variability and change, and the challenges of global plant-product insecurity.

Assessment of genetic diversity in salt-tolerant rice and its wild relatives for ten SSR loci and one allele mining primer of salT gene located on 1st chromosome

A heterogeneous collection of rice genotypes which included seven salt-tolerant rice lines, one salt-sensitive improved line, one wild rice (Oryza rufipogon) and one salt-tolerant wild rice relative (Porteresia coarctata) was screened with ten salt-tolerance-linked simple sequence repeat markers, of which nine were from the Saltol QTL mapped on rice 1st chromosome and the rest one from 8th chromosome, having high phenotypic variance for salt tolerance. Variation in molecular weight (in the form of base pairs) of the different amplified products using RM primers was used to find out the genetic relationship among the studied rice genotypes. Genomic DNA of the studied genotypes was also amplified with a reported allele mining primer for a salt-inducible gene (salT). The amplified products were sequenced and aligned to find out the closeness among the rice lines for the studied gene. Dendrogram derived from marker profiles showed partial similarity with salT gene-derived tree. Commonly, all the salt-tolerant lines were grouped into a single cluster, including IR36 (a salt-sensitive line) to which O. rufipogon (the wild rice) and P. coarctata (the wild rice relative) joined separately. The taxonomic identity and evolutionary relationship among the three groups (rice, wild rice and wild rice relative) were bioinformatically analysed using the nucleotide sequence of the studied salT gene.