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First published online July 21, 2006; 10.1104/pp.106.084475 Plant Physiology 142:280-293 (2006) © 2006 American Society of Plant Biologists Genomic Organization, Differential Expression, and Interaction of SQUAMOSA Promoter-Binding-Like Transcription Factors and microRNA156 in Rice1,[W]National Key Laboratory of Crop Genetic Improvement, National Center of Plant Gene Research (Wuhan), Huazhong Agricultural University, Wuhan 430070, China
Transcription factors play essential roles in the developmental processes of plants. Many such factors are regulated by microRNAs (miRNAs). SQUAMOSA (SQUA) promoter-binding-like (SPL) genes encode plant-specific transcription factors, some of which contain complementary sequences of miRNA156. In this study, 19 rice (Oryza sativa) SPL (OsSPL) genes and 12 rice miRNA156 (OsmiR156) precursors were identified in the rice genome. Sequence and experimental analysis suggested that 11 OsSPL genes were putative targets of OsmiR156. Plant SPL proteins were classified into six subgroups based on the phylogenetic analysis of SQUA promoter-binding protein domain. Diverse exon-intron structures and distinct organizations of putative motifs beyond the SQUA promoter-binding protein domains were identified in the OsSPL gene family. Transcript level analysis of OsSPL genes in various rice tissues and organs revealed different tempospatial expression patterns. More than half of the OsSPL genes including most OsmiR156-targeted genes are predominantly expressed in the young panicles, whereas OsmiR156 genes are predominantly expressed in the young shoots and leaves of rice. Overexpression of two OsmiR156 genes (OsmiR156b and OsmiR156h) in rice resulted in severe dwarfism, strongly reduced panicle size, and delayed flowering, suggesting that OsmiR156 and OsSPL target genes are involved in various developmental processes, especially the flower development of rice. Different patterns of transcript changes (decreased or unchanged) of different target genes in same tissue and of same target gene in different tissues detected in the OsmiR156-overexpressing plants suggested diverse interactions between OsmiR156 and OsSPL target genes in a tissue-specific manner.
1 This work was supported by grants from the National Program on High Technology Development, the National Program on the Development of Basic Research, and the National Natural Science Foundation, China. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Lizhong Xiong (lizhongx{at}mail.hzau.edu.cn). [W] The online version of this article contains Web-only data. www.plantphysiol.org/cgi/doi/10.1104/pp.106.084475 * Corresponding author; e-mail lizhongx{at}mail.hzau.edu.cn; fax 862787287092. Received June 1, 2006; accepted July 13, 2006. This article has been cited by other articles:
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