Journal Article

Self-incompatibility in <i>Papaver</i>: signalling to trigger PCD in incompatible pollen

Maurice Bosch and Vernonica E. Franklin-Tong

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 59, issue 3, pages 481-490
Published in print February 2008 | ISSN: 0022-0957
Published online September 2007 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jxb/erm195
Self-incompatibility in Papaver: signalling to trigger PCD in incompatible pollen

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Sexual reproduction in higher plants uses pollination, involving interactions between pollen and pistil. Self-incompatibility (SI) prevents self-fertilization, providing an important mechanism to promote outbreeding. SI is controlled by the S-locus; discrimination occurs between incompatible pollen, which is rejected, while compatible pollen can achieve fertilization. In Papaver rhoeas, S proteins encoded by the pistil part of the S-locus interact with incompatible pollen to effect rapid inhibition of tip growth. This self-incompatible interaction triggers a Ca2+-dependent signalling cascade. SI-specific events triggered in incompatible pollen include rapid depolymerization of the actin cytoskeleton; phosphorylation of soluble inorganic pyrophosphatases, and activation of a MAPK. It has recently been shown that programmed cell death (PCD) is triggered by SI. This provides a precise mechanism for the specific destruction of ‘self’ pollen. Recent data providing evidence for SI-induced caspase-3-like protease activity, and the involvement of actin depolymerization and MAPK activation in SI-mediated PCD will be discussed. These studies not only significantly advance our understanding of the mechanisms involved in SI, but also contribute to our understanding of functional links between signalling components and initiation of PCD in a plant cell. Recent data demonstrating SI-mediated modification of soluble inorganic pyrophosphatases are also described.

Keywords: Actin cytoskeleton; caspase; MAP kinase; Papaver rhoeas; pollen tube inhibition; programmed cell death (PCD); self-incompatibility

Journal Article.  6232 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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