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Perception et réaction géotropiques de l'épicotyle d'Asparagus officinalis
Author(s) -
PERBAL GÉRALD,
RIVIERE SIMONNE
Publication year - 1980
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1980.tb03218.x
Subject(s) - amyloplast , epicotyl , asparagus , gravitropism , endodermis , officinalis , biophysics , root cap , chemistry , botany , biology , arabidopsis , plastid , hypocotyl , biochemistry , meristem , mutant , chloroplast , shoot , gene
Geoperception and georeaction in Asparagus officinalis epicotyls The location and the role of the statenchyma were investigated in Asparagus officinalis epicotyls 1, 2 or 3 cm in length. The statocytes represent a monocellular sheath which comprises the outer layer of the pericycle. Three phases of differentiation (S 1 , S 2 , S 3 ) of the statocytes may be distinguished by criteria of cell length, the state of vacuolisation and the sedimentation of amyloplasts and nuclei with respect to gravity. The statenchyma was found to be located only in the first 10 mm of the epicotyl 1, 2 or 3 cm in length; in effect the oldest statocytes (S 3 ) differentiate into sclerenchyma beneath this level. The geotropic curvature of the epicotyls begins with a positive (downward) curvature and the negative (upward) response is only realized after 15–30 min of geotropic stimulation. The upper limit of the bending is located in the zone containing the mature statocytes (S 3 ), while the lower limit is located much closer to the base of the epicotyl. Experiments on decapitation of the epicotyls have indicated that the S 1 and S 2 statocytes do not play an important role in the perception of gravity. However, with S 3 statocytes, it has been demonstrated that there is a statistical correlation between the initial rate of curvature of the epicotyls and the length of their sheaths. Thus, the longer the sheath, the more the epicotyls curve. From the results obtained it is proposed that the statocytes are responsible for the geotropic perception of Asparagus officinalis epicotyls.