ASGSB 1999 Annual Meeting Abstracts

MICROTUBULE ORGANIZATION IN GRAVISTIMULATED CAULONEMATA OF PHYSCOMITRELLA PATENS. D.A.Collings¹, A. Shor², E.Johannes¹, N.S.Allen¹, E.B.Tucker². ¹Dept. of Botany, North Carolina State University, Raleigh, and ²Dept. Natural Sciences, Baruch College, City University of New York, New York.

Short term treatments of gravistimulated caulonemata of the moss Physcomitrella patens with the microtubule-depolymerizing herbicide oryzalin (0.1 mM, 5 min) resulted in branching at the apex of the tip cells. Immunofluorescence microscopy revealed that these brief treatments did not result in significant disruption to the longitudinally-oriented microtubules found in the majority of caulonemal cells. These treatments, however, caused reversible disorganization and depolymerization of the more dense and randomly-oriented microtubules that occur in the growing apicies of tip cells. While these observations confirm and extend earlier studies in various other moss species [Wacker et al. (1988) Protoplasma 142: 55-67; Schwuchow et al. (1990) Protoplasma 159: 60-69; Meske et al. (1996) Protoplasma 192: 189-198], they also help form a basis of a re-interpretation of a possible interplay between microtubules and calcium signaling in moss gravitropism.

(Supported by NASA grant #NAGW-4984.)

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