Genome-editing (GE) is having a tremendous influence around the globe in the life science community. Among its versatile uses, the desired modifications of genes, and more importantly the transgene (DNA)-free approach to develop genetically modified organism (GMO), are of special interest. The recent and rapid developments in genome-editing technology have given rise to hopes to achieve global food security in a sustainable manner. We here discuss recent developments in CRISPR-based genome-editing tools for crop improvement concerning adaptation, opportunities, and challenges. Some of the notable advances highlighted here include the development of transgene (DNA)-free genome plants, the availability of compatible nucleases, and the development of safe and effective CRISPR delivery vehicles for plant genome editing, multi-gene targeting and complex genome editing, base editing and prime editing to achieve more complex genetic engineering. Additionally, new avenues that facilitate fine-tuning plant gene regulation have also been addressed. In spite of the tremendous potential of CRISPR and other gene editing tools, major challenges remain. Some of the challenges are related to the practical advances required for the efficient delivery of CRISPR reagents and for precision genome editing, while others come from government policies and public acceptance. This review will therefore be helpful to gain insights into technological advances, its applications, and future challenges for crop improvement.

Centre of Research for Development University of Kashmir Srinagar 190006 India

Department of Agronomy Faculty of Agriculture Kafrelsheikh University Kafrelsheikh 33516 Egypt

Department of Bioresources University of Kashmir Srinagar 190006 India

Department of Biotechnology BGSB University Jammu 185234 India

Department of Botany and Plant Physiology Faculty of Agrobiology Food and Natural Resources Czech University of Life Sciences Prague Kamycka 129 165 00 Prague Czech Republic

Department of Crop Science Institute of Crop Science and Resource Conservation University Bonn 53115 Bonn Germany

Department of Field Crops Faculty of Agriculture Siirt University Siirt 56100 Turkey

Department of Horticulture Faculty of Agriculture Siirt University Siirt 56100 Turkey

Department of Plant Physiology Slovak University of Agriculture Nitra Tr A Hlinku 2 949 01 Nitra Slovakia

Division of Plant Pathology Sher e Kashmir University of Agricultural Sciences and Technology of Jammu Jammu 180009 India

ICAR National Institute for Plant Biotechnology New Delhi 110012 India

Mountain Research Centre for Field Crops Khudwani Sher e Kashmir University of Agricultural Sciences and Technology of Kashmir Jammu 192101 India

Plant Physiology and Biochemistry Section Department of Botany Aligarh Muslim University Aigarh 202002 India

School of Biotechnology Sher e Kashmir University of Agricultural Sciences and Technology of Jammu Jammu 180009 India

School of Biotechnology University of Jammu Jammu 180006 India

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