Browsing by Author "Kumar, Jitendra"

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Compendium of plant-specific CRISPR vectors and their technical advantages
(MDPI AG, 2021) Alok, Anshu; Chauhan, Hanny; Upadhyay, Santosh Kumar; Pandey, Ashutosh; Kumar, Jitendra; Singh, Kashmir
CRISPR/Cas mediated genome editing is a revolutionary approach for manipulating the plant genome. However, the success of this technology is highly dependent on selection of a specific vector and the other components. A plant-specific CRISPR/Cas vector usually consists of a Cas gene, target-specific gRNA, leader sequence, selectable marker gene, precise promoters, and other accessories. It has always been challenging to select the specific vector for each study due to a lack of comprehensive information on CRISPR vectors in one place. Herein, we have discussed every technical aspect of various important elements that will be highly useful in vector selection and efficient editing of the desired plant genome. Various factors such as the promoter regulating the expression of Cas and gRNA, gRNA size, Cas variants, multicistronic gRNA, and vector backbone, etc. influence transformation and editing frequency. For example, the use of polycistronic tRNA-gRNA, and Csy4-gRNA has been documented to enhance the editing efficiency. Similarly, the selection of an efficient selectable marker is also a very important factor. Information on the availability of numerous variants of Cas endonucleases, such as Cas9, Cas12a, Cas12b, Casɸ, and CasMINI, etc., with diverse recognition specificities further broadens the scope of editing. The development of chimeric proteins such as Cas fused to cytosine or adenosine deaminase domain and modified reverse transcriptase using protein engineering enabled base and prime editing, respectively. In addition, the newly discovered Casɸ and CasMINI would increase the scope of genetic engineering in plants by being smaller Cas variants. All advancements would contribute to the development of various tools required for gene editing, targeted gene insertion, transcriptional activation/suppression, multiplexing, prime editing, base editing, and gene tagging. This review will serve as an encyclopedia for plant-specific CRISPR vectors and will be useful for researchers.
Genome-wide QTL analysis for pre-harvest sprouting tolerance in bread wheat
(Springer, 2009) Mohan, Amita; Kulwal, Pawan; Singh, Ravinder; Kumar, Vinay; Mir, Reyazul Rouf; Kumar, Jitendra; Prasad, Manoj; Balyan, H. S.; Gupta, P. K.
A framework linkage map comprising 214 molecular marker (SSR, AFLP, SAMPL) loci was prepared using an intervarietal recombinant inbred line (RIL) mapping population of bread wheat. The RIL population that was developed from the cross SPR8198 (red-grained and PHS tolerant geno- type) 9 HD2329 (white-grained and PHS susceptible genotype) following single seed descent segregated for pre-harvest sprouting (PHS). The RIL population and parental genotypes were evaluated in six differ- ent environments and the data on PHS were collected. Using the linkage map and PHS data, genome-wide single-locus and two-locus QTL analyses were con- ducted for PHS tolerance (PHST). Single-locus analysis following composite interval mapping (CIM) detected a total of seven QTL, located on specific arms of five different chromosome (1AS,2AL, 2DL, 3AL and 3BL). These seven QTL included two major QTL one each on 2AL and 3AL. Two of these seven QTL were also detected following two-locus analysis, which resolved a total of four main-effect QTL (M-QTL), and 12 epistatic QTL (E-QTL), the latter involved in 7 QTL 9 QTL interactions. Interestingly, none of these M-QTL and E-QTL detected by two-locus analysis was involved in Q 9 E and Q 9 Q 9 E interactions, supporting the results of ANOVA, where genotype 9 environ- ment interaction were non-significant. The QTL for PHS detected in the present study may be efficiently utilized for marker-aided selection for enhancing PHST in bread wheat.