Investigating the targets and mechanisms regulating self incompatibility in papaver rhoeas pollen

Haque, Tamanna (2015). Investigating the targets and mechanisms regulating self incompatibility in papaver rhoeas pollen. University of Birmingham. Ph.D.

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Abstract

Many higher plants use self-incompatibil ity (SI) mechanism to prevent inbreeding and thus encouraging outcrossing. Upon a self-challenge in Papaver rhoeas, a Ca2+-dependent-signal ling-cascade is initiated resulting in the destruction ofthe self-pollen by Programmed Cell Death. Upstream ofPCD, several Sl-specific events are triggered in incompatible pollen, including phosphorylation of soluble inorganic pyrophosphatases (sPPases); alterations to actin; increases in Reactive Oxygen Species (ROS) and Nitric Oxide (NO). In Papaver pollen, sPPases play an important role, as they provide the driving force for biosynthesis; data suggested that Ca2+ and phosphorylation inhibits the sPPases activities, contributing to pollen tube inhibition. Work presented in this thesis characterized Pr-p26.1 sPPases and analysis of phosphomimic mutants in the SI signalling. These studies provide good evidence that, together with Ca2+, phosphorylation, H20 2 and pH dramatically affect sPPase activity.

As previous studies showed that increases in ROS and NO are triggered by Sl in incompatible pollen, to provide insights into SI-mediated events, this project investigated protein-targets in pollen modified by oxidation and Snitrosylations after Sl, including actin and actin-associated proteins. Using a mass spectrometry approach we identified several proteins that were modified by oxidation and S-nitrosylation. This has provided us with several potential new mechanisms involved in Sl.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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