Journal Article

Strigolactone Biosynthesis in Medicago truncatula and Rice Requires the Symbiotic GRAS-Type Transcription Factors NSP1 and NSP2

Hartog, Marijke, Geurts, René, Kaufmann, Kerstin, den Camp, Rik Op, Liu, Wei, Limpens, Erik, Bouwmeester, Harro J., Jamil, Muhammad, Ivanov, Sergey, Yang, Wei-Cai, Lillo, Alessandra, Smaczniak, Cezary, Hooiveld, Guido J.E.J., Kohlen, Wouter, Charnikhova, Tatsiana, Bisseling, Ton

2011

Overview

Legume GRAS (GAI, RGA, SCR)-type transcription factors MODULATION SIGNALING PATHWAY1 (NSP1) and NSP2 are essential for rhizobium Nod factor-induced nodulation. Both proteins are considered to be Nod factor response factors regulating gene expression after symbiotic signaling. However, legume NSP1 and NSP2 can be functionally replaced by nonlegume orthologs, including rice (Oryza sativa) NSP1 and NSP2, indicating that both proteins are functionally conserved in higher plants. Here, we show that NSP1 and NSP2 are indispensable for strigolactone (SL) biosynthesis in the legume Medicago truncatula and in rice. Mutant nsp1 plants do not produce SLs, whereas in M. truncatula, NSP2 is essential for conversion of orobanchol into didehydro-orobanchol, which is the main SL produced by this species. The disturbed SL biosynthesis in nsp1 nsp2 mutant backgrounds correlates with reduced expression of DWARF27, a gene essential for SL biosynthesis. Rice and M. truncatula represent distinct phylogenetic lineages that split approximately 150 million years ago. Therefore, we conclude that regulation of SL biosynthesis by NSP1 and NSP2 is an ancestral function conserved in higher plants. NSP1 and NSP2 are single-copy genes in legumes, which implies that both proteins fulfill dual regulatory functions to control downstream targets after rhizobium-induced signaling as well as SL biosynthesis in nonsymbiotic conditions.

• Publisher: American Society of Plant Biologists
• Subject: affymetrix genechip data / Alfalfa / Amino Acid Sequence / analysis / arbuscular mycorrhizal fungi / Biosynthesis / Carotenoids / Carotenoids - analysis / Carotenoids - metabolism / chemistry / Down-Regulation / Gene expression / Gene Expression Profiling / Gene Expression Regulation, Plant / Genes / genetics / germination stimulants / GRAS substances / growth & development / Lactones / Lactones - analysis / Lactones - chemistry / Lactones - metabolism / Legumes / lotus-japonicus / Medicago truncatula / Medicago truncatula - genetics / Medicago truncatula - growth & development / Medicago truncatula - microbiology / Medicago truncatula - physiology / metabolism / microbiology / Molecular Sequence Data / Mutation / nodulation / Oligonucleotide Array Sequence Analysis / Oryza / Oryza - genetics / Oryza - growth & development / Oryza - microbiology / Oryza - physiology / Oryza sativa / parasitic plants / Phenotype / phosphate deficiency / Phylogeny / physiology / Plant Growth Regulators / Plant Growth Regulators - metabolism / Plant Proteins / Plant Proteins - genetics / Plant Proteins - metabolism / Plant Root Nodulation / Plant Roots / Plant Roots - genetics / Plant Roots - growth & development / Plant Roots - microbiology / Plant Roots - physiology / Plants / quality assessment / red-clover / Rhizobium / Rice / Root exudates / Sesquiterpenes / Sesquiterpenes - metabolism / Signal Transduction / Sinorhizobium meliloti / Sinorhizobium meliloti - physiology / Symbiosis / tiller bud outgrowth / Transcription factors / Transcription Factors - genetics / Transcription Factors - metabolism / transduction pathway