CRISPR-Cas genome-editing tool in plant abiotic stress-tolerance

Adverse ambience caused by abiotic stresses affect the plant growth and increase the chances of low yield and resulting economic loss. To resolve this issue, several measures have been taken. Use of CRISPR/Cas gene-editing system to develop stress-resistant plant varieties has gained attention at present. Versatility of this user-friendly system has made it popular to the researchers. The DNA sequence family "CRISPR" and the endonuclease "Cas" work together in the gene-editing process following the direction by specific guide RNA. CRISPR/Cas system is applied in a number of plant species. Cas9 is frequently used in most of the cases. Several reports of the improvement of abiotic stress-tolerance in plants using CRISPR/Cas9 technology has been documented. Genomeediting efficiency of CRISPR/Cas9 system depends on some factors like Cas9 expression, RNA polymerase specificity, guide RNA expression, promoter sequence, types of transformation vectors etc. Sometimes, a few modifications of this system is needed to get expected outcomes. CRISPR/Cas9 system can be utilized in some prospective programmes like mutant library generation, reduction of agrochemical supplementation during cultivation, gene regulation, plant domestication etc. Basic and applied plant biology might be enriched through the further progress of CRISPR/Cas9 technology. The present review encompasses the applications of CRISPR-Cas genome-editing toolkit against abiotic stress-tolerance in many model as well as commercially important plants with notes on their genetic regulations. In addition, the article also outlines the existing shortcomings in past research with notes on future prospective.