Construction and characterization of a transformation-competent artificial chromosome (TAC) library ofZizania latifolia (Griseb.)

The tribe Oryzeae consists of 12 genera and 71 species with a world distribution.Zizania latifolia (Griseb.) Turcz. ex Stapf is included in this tribe and possesses numerous traits valuable for rice breeding, such as disease and insect resistance, cold and flood tolerance, and high grain quality. The genetics and breeding ofZ. latifolia are still in their infancy. To facilitate genomic studies ofZizania, a genomic DNA library was constructed using a transformation-competent artificial chromosome (TAC) vector system. The TAC library contains 91, 584 TAC clones with an average insert size of approximately 45 kb, covering six haploidZizania genome equivalents. Very low signals after hybridization with chloroplast and mitochondrial genes indicate that the TAC library is predominantly composed of nuclear DNA. The TAC clones were stable inE. coli for 100 generations. Clones containing thedihydrodipicolinate synthase (DHPS) gene were screened by pooled PCR. The positive clones can be used forZ. latifolia DHPS gene cloning and functional analysis. The library will be useful in studies of genome structure, gene cloning and evolution of rice.