Submitted to: Plant Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 7/3/2008
Publication Date: 9/17/2008
Publication URL: www.plantphysiol.org/cgi/reprint/148/3/1368
Citation: Zhang, D., Wengier, D., Shuai, B., Gui, C., Muschietti, J., McCormick, S.M., Tang, W. 2008. The Pollen Receptor Kinase LePRK2 Mediates Growth-Promoting Signals and Positively Regulates Pollen Germination and Tube Growth. Plant Physiology. 148:1368-1379. Interpretive Summary: Receptor kinases are proteins that are involved in receiving signals from other cells. We found that pollen with reduced expression of a pollen receptor kinase had several defects, including reduced germination, shorter pollen tubes, and lack of response to several signaling molecules. These results suggest that this kinase is important for pollen tube growth.
Technical Abstract: In flowering plants, the process of pollen germination and tube growth is required for successful fertilization. A pollen receptor kinase from tomato, LePRK2, has been implicated in signaling during pollen germination and tube growth as well as in mediating pollen (tube)-pistil communication. Here we show that reduced expression of LePRK2 affects four aspects of pollen germination and tube growth. First, the percentage of pollen that germinates is reduced, and the time window for competence to germinate is also shorter. Second, tube growth rate is reduced, and the expression level of LePRK2 is correlated with the tube growth rate. Third, tip-localized superoxide production by pollen tubes can not be increased by exogenous calcium ions. Fourth, pollen tubes have defects in responses to STIL, an extracellular growth-promoting signal from the pistil. Transient overexpression of LePRK2-fluorescent protein fusions gave slightly wider pollen tube tips, whereas pollen tube length was not affected. Together these results show that LePRK2 positively regulates pollen germination and tube growth and is involved in transducing responses to extracellular growth-promoting signals.