Abstract
Explants of guayule,Parthenium argentatum Gray, were treated with concentrations of ethephon varying from 0.5 to 10gl -1 for six days. The cut ends of the shoots were immersed in the solutions and allowed to stand so that the ethylene-releasing agent entered the explant via the transpiration stream. With higher concentrations of ethephon, defoliation of the explants commenced after one day and was 100% effective after six days. Lower concentrations were less effective. Examination of the petiole bases of treated explants at the light microscope level revealed enhanced development of abscission layers and hydrolytic degradation of the tissue immediately distal to these layers. This led to separation of the leaf which had become senescent. Food reserves appeared to have been mobilised from the senescent leaves. Histochemical staining and ultrastructural observations indicated loss of insoluble polysaccharides and cellulose from the induced separation layer. Pectic substances were lost to a lesser extent.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
AbelesFB (1972) Biosynthesis and mechanism of action of ethylene. Annu Rev P1 Phys 23:259–292
AddicottFT (1945) The anatomy of leaf abscission and experimental defoliation in guayule. Amer J Bot 32:250–256
AddicottFT (1982) Abscission. Berkeley: University of California Press
AddicottFT and LynchRS (1951) Acceleration and retardation of abscission by indoleacetic acid. Science 114:688–689
BenedictCR, ReibachPH, MadhavanS, StipanovicRV, KeithlyJH and YokoyamaH (1983) Effect of 2-(3,4-dichlorophenoxy)-triethylamine on the synthesis ofcis-polyisoprene in guayule plants (Parthenium argentatum Gray). Plant Physiol 72:897–899
BornmanCH (1967) Some ultrastructural aspects of abscission inColeus andGossypium. S Afr J Sci 63:325–331
DuvedeC (1960) Intracellular localization of enzymes. Nature 187:836–838
El-ZeftawiBM and DimseyRT (1983) Evaluation of abscission chemicals in various combinations for loosening Valencia oranges during re-greening. J. Hort Sci 58:129–139
HortonRF and OsbozneDJ (1967) Senescence, abscission and cellulase inPhaseolus vulgaris. Nature 214:1086–1088
JensenWA (1962) Botanical Histochemistry: Principles and Practice. San Francisco and London: W.H. Freeman
JohansenDA (1940) Plant microtechnique, New York: McGraw-Hill
LeeE (1911) The morphology of leaf fall. Ann Bot 25:52–103
LewisLN and VarnerJE (1970) Synthesis of cellulase during abscission ofPhaseolus vulgaris leaf explants. Plant Physiol 46:194–199
Lloyd FE (1911) Guayule (Parthenium argentatum Gray) — a rubber plant of the Chichuahuan desert. Carnegie Inst. Washington Pub 139
MatileP (1978) Biochemistry and function of vacuoles. Annu Rev P1 Phys 29:193–213
MayorHD, HamptonJC and RosarioB (1961) A simple method for removing the resin from epoxy-embedded tissue. J Biophys Biochem Cytol 9:909–910
NoelARA and VanStadenJ (1975) Phyllomorph senescence inStreptocarpus molweniensis. Ann Bot 39:921–929
OsborneDJ and SargentJA (1976) The positional differentiation of abscission zones during development of leaves ofSambucus nigra and the response of cells to auxin and ethylene. Planta 132:197–204
PolitoVS and LaveeS (1980) Anatomical and histochemical aspects of ethephon-induced leaf abscission in olive (Olea europaea). Bot Gaz 141:413–417
ReynoldsES (1963) Use of lead citrate at high pH as an electron opaque stain. J Cell Biol 17:208–212
ScottPC and LeopoldAC (1966) Abscission as a mobilization phenomenon. Plant Physiol 41:826–830
SextonR (1976) Some ultrastructural observations on the nature of foliar abscission inImpatiens sultani. Planta 128:49–58
SextonR and HallJL (1974) Fine structure and cytochemistry of the abscission zone ofPhaseolus leaves: Ultrastructural changes during abscission. Ann Bot 38:849–854
ValdovinosJG, JensenTE and SickoLM (1972) Fine structure of abscission zones. IV. Effect of ethylene on ultrastructure of abscission cells of tobacco flower pedicels. Planta 102:324–333
VigilEC (1969) Intracellular localization of catalase (peroxidatic) activity in plant microbodies. J Histochem Cytochem 17:425–428
WebsterBD (1973) Ultrastructural studies of abscission inPhaseolus: Ethylene effects on cell walls. Amer J Bot 60:426–447
Author information
Authors and Affiliations
Additional information
The financial support of Cooperative Scientific Programmes of the C.S.I.R. and technical assistance of the Electron Microscope Unit of the University of Natal, Pietermaritzburg is gratefully acknowledged.
Rights and permissions
About this article
Cite this article
Gilliland, M.G., Van Staden, J. Anatomical and ultrastructural changes associated with ethylene-induced defoliation of guayule explants. Plant Growth Regul 3, 149–158 (1985). https://doi.org/10.1007/BF01806054
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF01806054