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Abstract Detail

Non-Coding RNAs

Nogueira, Fabio TS [1], Madi, Shaminez [2], Chitwood, Daniel H [2], Timmermans, Marja CP [2].

Two Small Regulatory RNAs Establish Opposing Fates of a Developmental Axis.

Small RNAs are important regulators of gene expression in both animals and plants. Patterning and outgrowth of lateral organs in plants depend on the specification of adaxial/abaxial (dorsoventral) polarity in the incipient leaf. In maize, this dorsoventrality is established by an abaxial (ventral) gradient of microRNA166 (miR166) within the initiating primordium, which spatially restricts the expression domain of class III homeodomain leucine zipper (HD-ZIPIII) transcription factors that specify adaxial/dorsal fate. Specification of adaxial/abaxial organ polarity in maize also requires the activity of leafbladeless1 (lbl1), recessive mutations of which lead to formation of abaxialized leaves. We have cloned lbl1 and shown that it encodes a key component in the trans-acting siRNA (ta-siRNA) biogenesis pathway that acts on the adaxial side of developing leaves. Based on mutant and gene expression analyses, we propose a model for leaf patterning in which tasiR-ARF, a ta-siRNA, defines the adaxial side of the leaf by restricting the expression domain of abaxializing factors, such as miR166, which, in turn, delineates the abaxial side by restricting expression of the adaxializing HD-ZIPIII genes. Most importantly, our findings indicate that two small regulatory RNAs (tasiR-ARF and miR166) establish opposing domains along the adaxial-abaxial axis, thus revealing a novel mechanism of pattern formation.
Supported by: USDA and NSF.

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1 - Cold Spring Harbor laboratory, 1 Bungtown Rd - Delbruck building, Cold Spring Harbor, NY, 11724, USA
2 - Cold Spring Harbor Laboratory

trans-acting siRNA

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P25001
Abstract ID:539

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