Background
As the inflorescence of wheat, spike architecture largely determines grain productivity. Dissecting the genetic basis for spike morphology of wheat can contribute towards designation of ideal spike morphology to improve grain production.
Results
In this study, we characterized an EMS-induced mutant dense spike1 (ds1) from Nongda3753 (ND3753) with a dense spike and reduced plant height. Using bulked segregant analysis coupled with whole-genome sequencing (BSA-Seq) of two segregating populations, ds1 was mapped to the short arm of chromosome 7B. Further genotypic and phenotypic analyses of the residual heterozygous lines from F3 to F6 of Yong3002×ds1 revealed that there was a 0-135Mb deletion in chromosome 7B associated with the dense spike phenotype. The reads count analysis of the two bulks in BSA-Seq along with the cytological analysis of ds1, ND3753, NIL-ds1 and NIL-Y3002 confirmed the partial unidirectional translocation of 5AL (541-713Mb) to 7BS (0-135Mb) in ds1. This translocation resulted in an increase in copy number and expression of Q gene, thereby leading to the dense spike phenotype observed in ds1.
Conclusion
We identified a partial unidirectional translocation from 5AL to 7BS in an EMS-induced mutant ds1, which exhibiting dense spike phenotype. This research deepens our understanding of the dosage-dependent effect of Q gene on wheat spike morphology, and provides new materials with several chromosome structural variations for wheat breeding.