Minisymposium 6: Cytoskeleton

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Abs # M0604: Actin Cytoskeleton and Membrane Trafficking in Elongainputting Pollen Tubes

Presenter:	Cheung, Alice Y       Contact Presenter
Authors	Cheung, Alice Y (A)   Andreyeva, Tatyana  (A)   Niroomand, Shahriar  (A)   Wu, Hen-ming  (A)
Affiliations:	(A): University of Massachusetts, Dept. of Biochemistry and Molecular Biology

Pollen tubes are unique plant cells with a dramatic growth polarity. They elongate for long distances within the female reproductive tissues to transport the sperms to the ovules for fertilization. Growth is restricted to the tip and is supported by a polarized cytosolic organization. The apical region of elongating pollen tubes is occupied by transport vesicles to support the high secretory and endocytic activity that provides for the rapid tip growth. Larger organelles are located distal to the subapical region. The compartmentalized cellular organization is critical for growth and directionality (1). Underlying the organelle compartmentalization is an elaborate actin cytoskeleton. We study how the pollen tube maintains its actin dynamics and structure and the functional relationship between the actin cytoskeleton and vesicular trafficking. Formins and Rab GTPases are proteins that regulate actin-nucleation and vesicular trafficking, respectively (2,3). Their functional significance in maintaining pollen tube actin dynamics and tip-focused accumulation of transport vesicles, polar growth and directionality and will be discussed. Ref. 1.Cheung and Wu. 2006. Structural and Functional Compartmentalization in Pollen Tubes. J.Exp.Bot. In press. 2.Cheung and Wu. 2004. Over-expression of an Arabidopsis formin stimulates supernumerary actin cable formation from pollen tube cell membrane. Plant Cell 16, 257. 3.De Graaf, B. et al. (2005) Rab11 GTPase-Regulated Membrane Trafficking Is Crucial for Tip-Focused Pollen Tube Growth in Tobacco. Plant Cell 17, 2564. Our work is supported by grants from the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service (2003-35304-13241, 2005-35304-16030).