DWARF AND LOW‐TILLERING, a new member of the GRAS family, plays positive roles in brassinosteroid signaling in rice

Abstract

SUMMARYRapid 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 lowtillering (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 BRregulated 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.

Dynamic Cytology and Transcriptional Regulation of Rice Lamina Joint Development

“…Genes GRAS19 (Chen et al, 2013), LAZY1 (Li et al, 2007), CYP51G3 (Xia et al, 2015), and GSR1 ) present high expression levels at the lamina joint, validating their roles in lamina joint development. In addition, genes involved in the biosynthesis and signaling of BR and auxin, which have been implicated in important roles in the leaf angle, present diverse expression patterns, including decreased expression (CYP51G3 and CYCU4:1), increased expression (DLT [Tong et al, 2009] and GRAS19 and GH3-2 [Tong et al, 2012]), constant high expression levels (LIC and LAZY1 [Zhang et al, 2012]), and constant low expression levels (ILI1 [Zhang et al, 2009a] and REL1 [Chen et al, 2015a]), suggesting the complex regulation of leaf angles via different pathways.…”

Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice andArabidopsis

“…There is evidence that the rice heterotrimetric G protein a1 plays a role in BR signaling (Wang et al, 2006a;Oki et al, 2008). A few BR-regulated rice genes have been shown to contribute to BR-regulated development, including a direct target gene of BZR1 (Tong et al, 2009;Wang et al, 2009). Furthermore, many studies have shown important roles of BR in specific developmental processes.…”

Nitric Oxide and ProteinS-Nitrosylation Are Integral to Hydrogen Peroxide-Induced Leaf Cell Death in Rice

“…Total RNA was extracted using the TRIzol kit according to the user manual (GenStar; Tong et al, 2009). Two micrograms of total RNA treated with DNase I was used for cDNA synthesis with an RT kit (Promega).…”