title: Toward a molecular cytogenetic map for cultivated sunflower (Helianthus annuus L.) by landed BAC/BIBAC clones.
abstract: Conventional karyotypes and various genetic linkage maps have been established in sunflower (Helianthus annuus L., 2n = 34). However, the relationship between linkage groups and individual chromosomes of sunflower remains unknown and has considerable relevance for the sunflower research community. Recently, a set of linkage group-specific bacterial /binary bacterial artificial chromosome (BAC/BIBAC) clones was identified from two complementary BAC and BIBAC libraries constructed for cultivated sunflower cv. HA89. In the present study, we used these linkage group-specific clones (~100 kb in size) as probes to in situ hybridize to HA89 mitotic chromosomes at metaphase using the BAC-fluorescence in situ hybridization (FISH) technique. Because a characteristic of the sunflower genome is the abundance of repetitive DNA sequences, a high ratio of blocking DNA to probe DNA was applied to hybridization reactions to minimize the background noise. As a result, all sunflower chromosomes were anchored by one or two BAC/BIBAC clones with specific FISH signals. FISH analysis based on tandem repetitive sequences, such as rRNA genes, has been previously reported; however, the BAC-FISH technique developed here using restriction fragment length polymorphism (RFLP)-derived BAC/BIBAC clones as probes to apply genome-wide analysis is new for sunflower. As chromosome-specific cytogenetic markers, the selected BAC/BIBAC clones that encompass the 17 linkage groups provide a valuable tool for identifying sunflower cytogenetic stocks (such as trisomics) and tracking alien chromosomes in interspecific crosses. This work also demonstrates the potential of using a large-insert DNA library for the development of molecular cytogenetic resources.
authors: Department of Plant Sciences, North Dakota State University, Fargo, North Dakota 58108-6050, USA.
authors: Jiuhuan
authors: J
authors: Feng
authors: Zhao
authors: Z
authors: Liu
authors: Xiwen
authors: X
authors: Cai
authors: Chao-Chien
authors: CC
authors: Jan
mesh_terms: D002874:Chromosome Mapping; D022202:Chromosomes, Artificial, Bacterial / Q000235:genetics*; D003001:Cloning, Molecular; D020732:Cytogenetic Analysis / Q000379:methods; D015723:Gene Library; D006368:Helianthus / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length
keywords: BAC-FISH; RFLP genetic map; cytogenetic map; sunflower