Abstract
BackgroundVariability of heading date may assist in wheat adaptation to local environments. Thereafter, discovery of new heading date determinants is important for cereal improvement. In this study we used common wheat cultivar Chinese Spring (CS) and the substitution line of CS with 5B chromosome from T. dicoccoides (CS-5Bdic), different in their heading date by two weeks, to detect determinants of heading date on 5B chromosome.ResultsThe possible influence of the VRN-B1 gene, the most powerful regulator of flowering, located on 5B chromosome, to differences in heading time between CS and CS-5Bdic was studied. The sequencing of this gene from CS-5Bdic showed that an insertion of a nucleotide triplet produced an additional amino acid in the corresponding protein. No changes in the transcription levels of each homoeologous VRN-1 loci were found in CS-5Bdic by comparison with CS. To ascertain the loci determining heading date difference, a set of 116 recombinant inbred 5В chromosomal lines as a result of hybridization of CS with CS-5Bdic were developed and their heading dates were estimated. Using the Illumina Infinium 15 k Wheat platform, 379 5B-specific polymorphic markers were detected and a genetic map with 82 skeletal markers was constructed. Phenotype (heading date) – genotype association analysis revealed seventy eight markers in pericentromeric region of 5B chromosome significantly associated with heading date variation. Based on this estimation and synteny with model crop genomes we identified the three best candidate genes: WRKY, ERF/AP2 and FHY3/FAR1.ConclusionsWe supposed that the difference in activity of WRKY, ERF/AP2 and/or FHY3/FAR1 transcription factors between CS and CS-5Bdic to be a probable reason for the observed difference in heading dates. Data obtained in this study provide a good basis for the subsequent investigation of heading time pathways in wheat.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0688-x) contains supplementary material, which is available to authorized users.
Highlights
Variability of heading date may assist in wheat adaptation to local environments
Chinese Spring and substitution line CS-5Bdic were deposited in the EMBL, GenBank, and DDBJ nucleotide sequence databases under accession numbers [GenBank:KT750252] and [GenBank:KT750253], respectively
With the exception of a few substitutions located in intron 1, the VRN-B1 sequence of CS-5Bdic has only one significant change as compared to the CS VRN-B1 sequence, the insertion of three- nucleotide TCT in exon 7 leading to addition of the amino acid serine (S) in the C- terminal region of the protein
Summary
Sequence analysis of VRN-B1 genes from CS and CS-5Bdic The studied lengths of the VRN-B1 alleles, including promoter and coding regions, from CS and CS-5Bdic were 4780 bp and 4783 bp, respectively. RICLs’ phenotyping and SNP genotyping As opposed to no differences in expression level of VRN-1 homoeologous genes in CS and CS-5Bdic, CS5Bdic was characterized by delayed heading date during the development of recombinant inbred chromosomal lines (RICLs) and the difference in heading date between CS and CS-5Bdic was about 15 days (Fig. 2a). Due to the fact that the SNP markers of the employed array were developed according to coding sequences [27] we are able to compare them with existing databases of model species in order to detect candidate genes underlying heading date variation. Among the detected candidates there were genes controlling abiotic stress resistance of plants, providing damage protection, phytohormone metabolism, disease resistance and some transcription factors (Additional file 4: Table S4) From this set, we suggest the most probable candidates for heading time control are putative transcription factor genes WRKY, ERF/AP2 and FHY3/FAR1
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