Map-based cloning and characterization of a gene controlling hairiness and seed coat color traits in Brassica rapa.
A glabrous, yellow-seeded doubled haploid (DH) line and a hairy, black-seeded DH line in Chinese cabbage (B. rapa) were used as parents to develop a DH line population that segregated for both hairiness and seed coat color traits. The data showed that both traits completely co-segregated each other, suggesting that one Mendelian locus controlled both hairiness and seed coat color in this population. A fine genetic map was constructed and a SNP marker that was located inside a Brassica ortholog of TRANSPARENT TESTA GLABRA 1 (TTG1) in Arabidopsis showed complete linkage to both the hairiness and seed coat color gene, suggesting that the Brassica TTG1 ortholog shared the same gene function as its Arabidopsis counterpart. Further sequence analysis of the alleles from hairless, yellow-seeded and hairy, black-seeded DH lines in B. rapa showed that a 94-base deletion was found in the hairless, yellow-seeded DH lines. A nonfunctional truncated protein in the hairless, yellow-seeded DH lines in B. rapa was suggested by the coding sequence of the TTG1 ortholog. Both of the TTG1 homologs from the black and yellow seeded B. rapa lines were used to transform an Arabidopsis ttg1 mutant and the results showed that the TTG1 homolog from the black seeded B. rapa recovered the Arabidopsis ttg1 mutant, while the yellow seeded homolog did not, suggesting that the deletion in the Brassica TTG1 homolog had led to the yellow seeded natural mutant. This was the first identified gene in Brassica species that simultaneously controlled both hairiness and seed coat color traits.
Zhang
Jiefu
J
Department of Plant Science, University of Manitoba, Winnipeg, Canada R3T 2N2.
Lu
Ying
Y
Yuan
Yuxiang
Y
Zhang
Xiaowei
X
Geng
Jianfeng
J
Chen
Yu
Y
Cloutier
Sylvie
S
McVetty
Peter B E
PB
Li
Genyi
G
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics; D001483:Base Sequence; D029741:Brassica rapa / Q000235:genetics*; D020090:Chromosome Segregation / Q000235:genetics; D003001:Cloning, Molecular; D017343:Genes, Plant; D006238:Haploidy; D008969:Molecular Sequence Data; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010858:Pigmentation / Q000235:genetics*; D018515:Plant Leaves / Q000033:anatomy & histology; D019655:Quantitative Trait, Heritable; D012639:Seeds / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014170:Transformation, Genetic
D029681:Arabidopsis Proteins; C121067:TTG1 protein, Arabidopsis