Analyzing the soybean transcriptome during autoregulation of mycorrhization identifies the transcription factors GmNF-YA1a/b as positive regulators of arbuscular mycorrhization

Reference Report for RTN20151124.1

Title:	Analyzing the soybean transcriptome during autoregulation of mycorrhization identifies the transcription factors GmNF-YA1a/b as positive regulators of arbuscular mycorrhization
Authors:	Schaarschmidt, S., Gresshoff, P.M., Hause, B.
Source:	Genome Biol. 2013, 14(6):R62
Abstract:	BACKGROUND: Similarly to the legume-rhizobia symbiosis, the arbuscular mycorrhizainteraction is controlled by autoregulation representing a feedback inhibitioninvolving the CLAVATA1-like receptor kinase NARK in shoots. However, little isknown about signals and targets down-stream of NARK. To find NARK-relatedtranscriptional changes in mycorrhizal soybean (Glycine max) plants, we analyzed wild-type and two nark mutant lines interacting with the arbuscular mycorrhizafungus Rhizophagus irregularis.RESULTS: Affymetrix GeneChip analysis of non-inoculated and partially inoculated plants in a split-root system identified genes with potential regulation byarbuscular mycorrhiza or NARK. Most transcriptional changes occur locally during arbuscular mycorrhiza symbiosis and independently of NARK. RT-qPCR analysisverified nine genes as NARK-dependently regulated. Most of them have lowerexpression in roots or shoots of wild type compared to nark mutants, includinggenes encoding the receptor kinase GmSIK1, proteins with putative function asornithine acetyl transferase, and a DEAD box RNA helicase. A predicted annexinnamed GmAnnx1a is differentially regulated by NARK and arbuscular mycorrhiza indistinct plant organs. Two putative CCAAT-binding transcription factor genesnamed GmNF-YA1a and GmNF-YA1b are down-regulated NARK-dependently in non-infectedroots of mycorrhizal wild-type plants and functional gene analysis confirmed apositive role for these genes in the development of an arbuscular mycorrhizasymbiosis.CONCLUSIONS: Our results indicate GmNF-YA1a/b as positive regulators inarbuscular mycorrhiza establishment, whose expression is down-regulated by NARKin the autoregulated root tissue thereby diminishing subsequent infections. Genesregulated independently of arbuscular mycorrhization by NARK support anadditional function of NARK in symbioses-independent mechanisms.

Funded by the USDA-ARS. Developed by the USDA-ARS SoyBase and Legume Clade Database group at the Iowa State University, Ames, IA

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