**2.3 Transcription activator-like effector nucleases (TALENs)**

The TALEN (transcription activator-like effector nucleases) technology was developed in 2011 to optimize the effectiveness, reliability, and availability of genome editing. Transcription activator-like effectors (TALES) were discovered [25, 26]. The TALEN, like ZFNs, creates proteins artificially with a flexible array of DNA-binding regions joined to FokI's nonspecific fragmentation site. Each repeat consists of 33–35 amino acids and identifies just one nucleotide. The last repetition is considered as a "half-repeat" since it frequently contains 20 amino acids. The varied amino acids at positions 12 and 13 provide DNA identifying distinctiveness (for example, NI accepts adenine, HD detects cytosine, NG detects thymine, and NN recognizes both guanine and adenine) [27, 28]. TAL effectors have natural segmentation grace to facilitate genome editing in TALENs, where these repetitions are organized to find individual regions of expression. Additional TALENs and gene-specific stimulators and regulatory proteins were employed as gene targeting reagents in conjunction with TAL effector assemblies [29–31]. TALENs are more adaptable compared to meganucleases and ZFNs and are used extensively in plant genome editing. However, a large number of experiments renders TALEN production as well as transport throughout plant tissue problematic.
