title: Identification and phylogenetic analysis of a CC-NBS-LRR encoding gene assigned on chromosome 7B of wheat.
abstract: Hexaploid wheat displays limited genetic variation. As a direct A and B genome donor of hexaploid wheat, tetraploid wheat represents an important gene pool for cultivated bread wheat. Many disease resistant genes express conserved domains of the nucleotide-binding site and leucine-rich repeats (NBS-LRR). In this study, we isolated a CC-NBS-LRR gene locating on chromosome 7B from durum wheat variety Italy 363, and designated it TdRGA-7Ba. Its open reading frame was 4014 bp, encoding a 1337 amino acid protein with a complete NBS domain and 18 LRR repeats, sharing 44.7% identity with the PM3B protein. TdRGA-7Ba expression was continuously seen at low levels and was highest in leaves. TdRGA-7Ba has another allele TdRGA-7Bb with a 4 bp deletion at position +1892 in other cultivars of tetraploid wheat. In Ae. speltoides, as a B genome progenitor, both TdRGA-7Ba and TdRGA-7Bb were detected. In all six species of hexaploid wheats (AABBDD), only TdRGA-7Bb existed. Phylogenic analysis showed that all TdRGA-7Bb type genes were grouped in one sub-branch. We speculate that TdRGA-7Bb was derived from a TdRGA-7Ba mutation, and it happened in Ae. speltoides. Both types of TdRGA-7B participated in tetraploid wheat formation. However, only the TdRGA-7Bb was retained in hexaploid wheat.
authors.affiliation: State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, No.1 West Beichen Road, Chaoyang District, Beijing 100101, China. cygong@genetics.ac.cn
authors.forename: Caiyan
authors.initials: C
authors.lastname: Gong
authors.forename: Shuanghe
authors.initials: S
authors.lastname: Cao
authors.forename: Renchun
authors.initials: R
authors.lastname: Fan
authors.forename: Bo
authors.initials: B
authors.lastname: Wei
authors.forename: Guiping
authors.initials: G
authors.lastname: Chen
authors.forename: Xianping
authors.initials: X
authors.lastname: Wang
authors.forename: Yiwen
authors.initials: Y
authors.lastname: Li
authors.forename: Xiangqi
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics*; D032461:Chromosomes, Plant / Q000235:genetics; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D014644:Genetic Variation; D000090263:Leucine-Rich Repeat Proteins; D018895:Microsatellite Repeats / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics*; D011506:Proteins / Q000235:genetics*; D018911:Trinucleotide Repeats / Q000235:genetics; D014908:Triticum / Q000235:genetics*
chemical_list: D002352:Carrier Proteins; D000090263:Leucine-Rich Repeat Proteins; D010940:Plant Proteins; C486364:Pm3b protein, Triticum aestivum; D011506:Proteins