Premium
Uncoupling secretion and tip growth in lily pollen tubes: evidence for the role of calcium in exocytosis
Author(s) -
Roy Stéphane J.,
HoldawayClarke Terena L.,
Hackett Grant R.,
Kunkel Joseph G.,
Lord Elizabeth M.,
Hepler Peter K.
Publication year - 1999
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1999.00515.x
Subject(s) - exocytosis , calcium , secretion , elongation , pollen tube , biophysics , extracellular , tip growth , cytoplasm , pollen , arabinogalactan , chemistry , microbiology and biotechnology , biology , biochemistry , cell wall , botany , materials science , organic chemistry , pollination , metallurgy , ultimate tensile strength
Summary Cytoplasmic calcium concentration ([Ca 2+ ] i ) and extracellular calcium (Ca 2+ o ) influx has been studied in pollen tubes of Lilium longliflorum in which the processes of cell elongation and exocytosis have been uncoupled by use of Yariv phenylglycoside ((β‐D‐Glc) 3 ). Growing pollen tubes were pressure injected with the ratio dye fura‐2 dextran and imaged after application of (β‐D‐Glc) 3 , which binds arabinogalactan proteins (AGPs). Application of (β‐D‐Glc) 3 inhibited growth but not secretion. Ratiometric imaging of [Ca 2+ ] i revealed an initial spread in the locus of the apical [Ca 2+ ] i gradient and substantial elevations in basal [Ca 2+ ] i followed by the establishment of new regions of elevated [Ca 2+ ] i on the flanks of the tip region. Areas of elevated [Ca 2+ ] i corresponded to sites of pronounced exocytosis, as evidenced by the formation of wall ingrowths adjacent to the plasma membrane. Ca 2+ o influx at the tip of (β‐D‐Glc) 3 ‐treated pollen tubes was not significantly different to that of control tubes. Taken together these data indicate that regions of elevated [Ca 2+ ] i , probably resulting from Ca 2+ o influx across the plasma membrane, stimulate exocytosis in pollen tubes independent of cell elongation.