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Abstract Detail


Pollen Biology

Lorbiecke, Renť [1], Pinto, Sheena [2], Kluth, Jantjeline [1], Pusunc, Susan [1], Buchert, Eva [1], Herrmann, Markus M. [1], Wienand, Udo [1].

The pollen-specific protein kinase ZmPTI1a from maize co-localizes with callose deposition and facilitates a competitive advantage to the male gametophyte.

The serin-threonin protein kinases LePTO and LePTI1 (Pto interactor 1) are known to be involved in gene-for-gene recognition and hypersensitive response (HR) signaling during resistance to Pseudomonas syringae in tomato. However, the exact role of LePTI1 is uncertain. So far no Pti1 genes have been studied in crop plants. In order to decipher the function of PTI1-homologues in maize (Zea mays L.), four Pti1-like kinase genes (ZmPti1a -d) were cloned.
In this study, ZmPTI1a was examined in terms of its expression and function. In contrast to LePTI1 from tomato, expression of the functional kinase ZmPTI1a is highly specific to pollen. Maize plants in which ZmPTI1a expression was silenced by RNAi produced pollen with a decreased competitive ability compared to wild type pollen. Stable expression of GFP fusions demonstrated that ZmPTI1a is sequestered at the pollen plasma membrane due to N-terminal acylation. Interestingly, the protein was not equally distributed at the membrane but accumulated as a distinct annulus-like structure. This structure co-localized with regions of callose (1,3-beta-glucan) deposition. Co-localization of ZmPTI1a and callose was also observed at different stages of pollen mitosis and during pollen tube germination. Putative ZmPTI1a-interacting proteins were identified in a two-hybrid screen and suggested ZmPTI1 to be probably linked to lipid- and/or Ca2+-signaling modules.
Pollen-sporophyte interaction and pathogen induced HR show certain similarities, e.g. callose deposition, Ca2+- and oxidative-stress-signaling. Based on our data on PTI1-like kinases from maize we hypothesize that these proteins act as general components in evolutionary conserved signaling processes but during different developmental programs and in different tissue types.


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1 - Universitšt Hamburg, Biozentrum Klein Flottbek, Ohnhorststrasse 18, Hamburg, 22609, Germany
2 - Deutsches Krebsforschungszentrum, Heidelberg, Germany
3 - Universitšt Hamburg, Biozentrum Klein Flottbek, Ohnhorststrasse 18, Hamburg, 22609, Germany

Keywords:
pollen
hypersensitive response
myristoylation
RNAi
protein kinase signaling
callose.

Presentation Type: ASPB Minisymposium
Session: M12
Location: Waldorf Room/Hilton
Date: Monday, July 9th, 2007
Time: 9:45 AM
Number: M12004
Abstract ID:657


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