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United States Department of Agriculture

Agricultural Research Service

Title: Lestig1, An Extracellular Binding Partner for the Pollen Receptor Kinases Leprk1 and Leprk2, Promotes Pollen Tube Growth in Vitro

Authors
item McCormick, Sheila
item Tang, Weihua - ARS-UCB PLNT GENE EXP CTR
item Kelley, Dior - ARS-UCB PLNT GENE EXP CTR
item Ezcurra, Inez - ARS-UCB PLNT GENE EXP CTR

Submitted to: Plant Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2004
Publication Date: August 1, 2004
Citation: Tang, W., Kelley, D., Ezcurra, I., McCormick, S. 2004. LeSTIG1, an extracellular binding partner for the pollen receptor kinases LePRK1 and LePRK2, promotes pollen tube growth in vitro. Plant Journal, 39(3):343-53.

Interpretive Summary: The tomato pollen-specific receptor kinases LePRK1 and LePRK2 might participate in signaling during pollen tube growth. We previously showed that the extracellular domain of LePRK2 interacts with LAT52, before but not after pollen germination. We characterized proteins that were identified in yeast two-hybrid screens. We show that LeSHY and LeSTIG1 can bind both LePRK1 and LePRK2. Binding assays with the LePRK2 suggested that LeSTIG1 could displace binding of LAT52. LEPRK1 and LePRK2 are involved in mediating pollen-pistil interactions.

Technical Abstract: As pollen tubes grow through the pistil they are thought to perceive and respond to diverse signals. The tomato pollen-specific receptor kinases LePRK1 and LePRK2 might participate in signaling during pollen tube growth. We previously showed that the extracellular domain of LePRK2 interacts with a pollen protein, LAT52, before but not after pollen germination. To determine whether LePRK2 might have different binding partner(s) after pollen germination, we characterized two more proteins that, like LAT52, were identified in yeast two-hybrid screens using the extracellular domains of LePRK1 and LePRK2 as baits. We show that LeSHY, a leucine-rich repeat protein from pollen, and LeSTIG1, a small cysteine-rich protein from pistil, can bind the extracellular domains of both LePRK1 and LePRK2 in vitro. In vitro binding assays with the extracellular domain of LePRK2 suggested that LeSTIG1 could displace binding of LAT52, consistent with the idea that LePRK1 and LePRK2 might interact with different ligands at different stages of pollen tube growth. Exogenous LeSTIG1 promotes pollen tube growth in vitro. The interaction of these pollen kinases with LeSTIG1 supports the notion that LePRK1 and LePRK2 are involved in mediating pollen-pistil interactions.

Last Modified: 10/21/2014
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