FISH PHYSICAL MAPPING OF TWO SINGLE-COPY STRESS-RELATED GENES NAC1 AND CLD IN Zea mays

Center for Developmental Biology, Wuhan University, Wuhan, 430072, P. R. China

The genes nac1 and cld play key roles in salt stress and cold or heat shock respectively in maize. Recent studies showed that programmed cell death (PCD)process was involved in salt, cold and heat stresses in plants. Using a biotin-labeled fluorescence in situ hybridization (FISH) technique, we have physically mapped the cDNAs corresponding to nac1 and cld respectively onto maize chromosomes. Gene nac1 was localized on the long arm of chromosomes 10 (10L) and there was its homologous sequence on the short arm of chromosome 2 (2S), the percentage distances from the hybridization sites on 10L and 2S to the centromeres were 71.3A1C02.7 and 65.6A1C03.8 respectively, and gene cld on 4L and its homologous sequence on 5L, the percentage distances on 4L and 5L were 68.6A1C02.6 and 58.2A1C01.6 separately. Our results validated the positions of nac1 and cld where were at linkage groups 10 and 4 in genetic map. Moreover, we found the duplicated sequences homologous to these two genes on 2L and 5L. The homologous sequences did not show any site in the genetic map, this demonstrated that they had no the corresponding phenotypes.