Qin, Yuan , Palanivelu, Ravishankar .
Identifying the pistil gene network that regulates final stages of pollen tube guidance.
A pollen tube navigates past different pistil cells before it reaches the egg to effect fertilization and disruption in pollen tube guidance results in no seed formation. Pistil cells provide nutritional and navigation cues to guide pollen tubes to ovules, yet only a few have been identified. We are using arabidopsis actin-related protein 6 (ARP6) to isolate signals from female sporophytic cells that mediate the final stages of pollen tube growth to ovules. ARP6 is a component of chromatin remodeling complex involved in regulating gene expression. arp6 mutant plants are characterized by defects in pistil tissues causing low seed set. To explore the basis of low seed set, Lat52:GUS pollen was grown on WT or arp6 pistils and stained for Gus activity. In the arp6 pistils, although pollen tube germination and growth were comparable to WT, only 54.28% of ovules were targeted by pollen tubes compared to WT (86.90%). In order to pinpoint which arp6 pistil tissue is defective, we performed in vitro pollen tube guidance assay involving several different combinations of WT and arp6 pistil and ovules. When Lat52:GFP pollen tubes approached WT ovules after traveling through WT or arp6 pistils, ~50% of the ovules were targeted. However, if the LAT52:GFP pollen tubes grew through WT or arp6 pistils and approached arp6 ovules, only 35% of the ovules were targeted suggesting that the arp6 ovule defects resulted in low seed set. To identify the ovule gene network associated with final stages of pollen tube guidance, we compared gene expression changes in arp6 and WT ovules by microarray analysis. Progress on the microarray experiments and characterization of these genes will be reported.
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1 - University of Arizona, Department of Plant Sciences
2 - University of Arizona, Department of Plant Sciences, 1145 E 4th St, Marley 503, Tucson, AZ, 85721, USA
pollen tube guidance
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM