title: DWARF AND LOW-TILLERING, a new member of the GRAS family, plays positive roles in brassinosteroid signaling in rice.
abstract: Rapid progress has been made regarding the understanding of brassinosteroid (BR) signaling in Arabidopsis. However, little is known about BR signaling in monotyledons. Here, we characterized a rice dwarf and low-tillering (dlt) mutant and cloned the corresponding gene via map-based cloning. DLT encodes a new member of the plant-specific GRAS family. The dwarf phenotype of dlt is similar to BR-deficient or signaling mutants in rice. In addition, both lamina bending and coleoptile elongation assays show that dlt is insensitive or much less responsive to brassinolide (BL), the most active BR, suggesting that DLT is involved in BR signaling. Consistent with this conclusion, the accumulation of transcripts of BR biosynthesis genes in the dlt mutant indicated that DLT is involved in feedback inhibition of BR biosynthesis genes. In addition, transcription of several other BR-regulated genes is altered in the dlt mutant. Finally, consistent with the fact that DLT is also negatively feedback-regulated by BR treatment, a gel mobility shift assay showed that OsBZR1 can bind to the DLT promoter through the BR-response element. Taken together, these studies have enabled us to identify a new signaling component that is involved in several specific BR responses in rice.
authors.affiliation: State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Hongning
authors.initials: H
authors.lastname: Tong
authors.forename: Yun
authors.initials: Y
authors.lastname: Jin
authors.forename: Wenbo
authors.initials: W
authors.lastname: Liu
authors.forename: Feng
authors.initials: F
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Fang
authors.forename: Yanhai
authors.initials: Y
authors.lastname: Yin
authors.forename: Qian
authors.initials: Q
authors.lastname: Qian
authors.forename: Lihuang
authors.initials: L
authors.lastname: Zhu
authors.forename: Chengcai
authors.initials: C
authors.lastname: Chu
mesh_terms: D000595:Amino Acid Sequence; D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism*; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D013260:Steroids, Heterocyclic / Q000378:metabolism*
chemical_list: D060406:Brassinosteroids; D002777:Cholestanols; D018744:DNA, Plant; D010940:Plant Proteins; D013260:Steroids, Heterocyclic; C023623:brassinolide