Plant Genome IV Conference Plant Genome IV Conference
Characterisation of the 79,000 maize YAC clones which constitute the Zeneca maize YAC library continues. Todate the library has been screened with over 200 single copy probes from various sources. Screening of the library is carried out using both a PCR screening protocol and robot aided high density colony hybridisation. Using both of these procedures we have been able to identify YAC's for approximately 95% of the probes used as well as identifying all YAC's containing chloroplast (over 4,000 in total), ribosomal (~200) and knob heterochromatin (~600) sequences. Screening the library with the available (as of August 94) chromosome one probes has resulted in YAC clones covering approximately 5% of the chromosome. A lack of probes from chromosome one has now forced us to examine new ways of generating chromosome one probes including RFLP's, AFLP's and SSR's. We have used the repetitive DNA present within the maize genome to fingerprint individual maize YAC's and construct small contigs of up to 800 kb. Limited resources in the future will almost certainly reduce the amount of work that can be carried out with the library, however, for the time being the YAC library is still available for screening.