What are the current approaches and challenges in genome writing/synthesis?

Genome writing involves synthesizing and assembling entire chromosomes or genomes. Approaches include: hierarchical assembly from oligonucleotides through Gibson/Golden Gate methods (Sc2.0 yeast genome project), synthesis and transplantation (JCVI Mycoplasma synthesis), and chromosome-scale DNA assembly using yeast homologous recombination. Technical challenges include: synthesis accuracy over megabase scales, designing for viability while incorporating modifications, booting synthetic genomes, and debugging non-functional constructs. Design challenges involve understanding essential gene requirements, maintaining genome stability, and incorporating genetic safeguards. Applications span fundamental biology research, engineered chassis organisms, and creating organisms with novel functions. Ethical considerations address dual-use potential and biosafety. Cost and throughput continue improving.