Fine mapping of BH1, a gene controlling lemma and palea development in rice
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A new rice floral organ mutant bh1 , had a negative effect on grain yield. BH1 was fine mapped to 87.5 kb on chr2. A 55 kb chromosome segment was deleted in bh1.
The cereal spikelet is enclosed by the lemma and palea. The lemma and palea of the floral mutant designated bh1, a selection from a T-DNA library generated from the rice cultivar Asominori, takes on an abnormal curve-shaped appearance only late in floral development, finally forming a beak-shaped hull. The mutation had a negative effect on thousand grain weight, seed set rate and germination rate. Genetic analysis indicated that the mutant phenotype was determined by a single recessive gene. Through map-based approach, BH1 gene was finally located to a ~87.5-kbp region on the long arm of chromosome 2. An analysis of the gene content of this region indicated that the mutation involves the loss of a 55-kbp stretch, harboring four open reading frames. Transcription profiling based on qRT-PCR revealed that the genes OsMADS1, OsMADS14, OsMADS15, OsMADS18, REP1, CFO1, and DL, all of which are also involved in lemma and palea development and identity specification, were down-regulated in the bh1 mutant. BH1 is therefore an important floral organ development gene.
KeywordsGene mapping Beak-shaped hull Floral organ Chromosome segment deletion Rice
We acknowledge the financial support given by the Natural Science Foundation of China (31201195), the Zhejiang province Science and Technology Project (2010C32061), the Chinese government “863” Program (2011AA10A101, 2012AA101101), the National S and T Major Project (2011ZX08001-001, 2011ZX08001-002 and 2011ZX08001-006), and the Central level, non-profit, scientific research institutes basic R and D operations Special Fund (2012RG002-1).