Received: 07 Oct 2021 Accepted: 13 Nov 2021 Revised: 09 Nov 2021 https://doi.org/10.37992/2021.1204.147 Vol 12(4):1060 - 1068 1060 Electronic Journal of Plant Breeding Research Article Genome editing of elite rice cultivar CO51 for bacterial leaf blight resistance T. Arulganesh 1 , Yaiphabi Kumam 1 , K. K. Kumar 1 , L. Arul 1 , E. Kokiladevi 1 , S. Nakeeran 1 , S. Varanavasiappan 1 , S. Manonmani 2 and D. Sudhakar 1* 1 Department of Plant Biotechnology, Centre for Plant Molecular Biology and Biotechnology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. 2 Department of Plant Genetic Resources, Centre for Plant Breeding and Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India. *E-Mail: dsudhakar@hotmail.com Abstract Bacterial leaf blight (BLB) of rice caused by Xanthomonas oryzae pv oryzae (Xoo) is a major constraint in rice production. Natural resistance to BLB in some of the wild type cultivars of rice is due to mutations in efector binding element (EBE), present in the promoter region of SWEET genes. SWEET14 is one of the most commonly targeted genes by majority of the TALEs of Xoo pathogen. Thus, the present study was aimed at creating novel mutations in the EBE of OsSWEET14 gene in indica rice cultivar, CO51 through CRISPR/Cas9 mediated genome editing technology to impart resistance against BLB. Agrobacterium-mediated transformation using immature embryos followed by regeneration resulted in eleven transgenic plants from six independent transformation events, of which nine plants (belonging to fve events) had mutations in the target sequence. Bioassay studies on four mutant plants (belonging to three events) resulted in the identifcation of two plants (belonging to two events) with resistance/moderately resistance against BLB. Key words: Rice, SWEET genes, CRISPR/Cas9, Bacterial Leaf Blight, Efector Binding Element INTRODUCTION Rice (Oryza sativa) is a cereal crop that is consumed by half of the global population (Fukagawa and Ziska, 2019). High population growth, limited arable land, shortage of other natural resources and outbreak of crop diseases limit rice cultivation and production (FAO, 2017). Among these constraints, yield loss due to diseases is a serious concern, contributing up to 16 per cent globally (Ficke et al., 2018). Bacterial leaf blight (BLB) is one of the major foliage diseases that attack the rice crop seasonally. Yield losses due to BLB have been reported to vary from 2 to 74 per cent depending on location, season, crop growth stage and cultivar (Rao and Kaufman, 1977; Reddy et al., 1978). Major symptoms of BLB include water soaked yellowish stripes on leaf blades, curling of leaves and early morning appearance of bacterial ooze on young lesions on the leaves (Nino-Liu et al., 2006). The pathogen, Xanthomonas oryzae pv. oryzae (Xoo) targets SWEET (Sugar will eventually be exported transporters) genes in rice during BLB infection. Even though the rice genome has more than 20 SWEET genes, only three (OsSWEET11, OsSWEET13 and OsSWEET14) are targeted by the Xoo pathogen, and these genes are called ‘susceptible (S) genes’ (Oliva et al., 2019). During infection with BLB, the Xoo pathogen secretes Transcription Activator like Efector (TALE) molecules which bind to the efector binding element (EBE) in the promoter region of some of the rice SWEET genes. The binding of TALEs to the promoter region results in the over-expression of SWEET genes. Over-expression of SWEET genes results in the production of sugars,