Telomeres are special protein-DNA structures at the end of linear chromosomes,which are essential for genome stability and basically maintained by telomerase.In budding yeast Saccharomyces cerevisiae,telomerase-negative cells readily undergo senescence.However,very few cells (survivors) bypass the survival crisis and maintain the telomere via homologous recombination.Survivors can be categorized into two types: type I and type Ⅱ,which are defined by Rad51 and Rad50 respectively.The telomeric DNAs possess different structure in the different survivors.To elucidate the network contributing to different survivor formation in budding yeast,we carried out a large-scale screening in the telomere maintenance genes whose deletion would cause telomere length change.Genes required for type I and type II survivors are screened based on the different production rate in liquid and solid media.The screening is on process at present.To date,8 genes have been confirmed to be required for type I survivor formation while 22 genes are required for type II survivor existence.These genes fall into various biological processes,such as glycol-metabolism,RNA decay and processing,sister chromatid cohesion,ubiquitination,and so on.The screening will yield a comprehensive network of how telomere recombination is coordinated in the telomerase-negative cells and provide plentiful proposals to the underlying telomere recombination mechanisms.Several interesting pathways like sister chromatid cohesion loading will be subjected to further analysis,and it may shed new light on the linkage of telomere length maintenance,recombination and survivor formation mechanisms.