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Phycornyces: TURGOR PRESSURE BEHAVIOR DURING THE LIGHT AND AVOIDANCE GROWTH RESPONSES
Author(s) -
Ortega Joseph K. E.,
Manica Keith J.,
Keanini Russell G.
Publication year - 1988
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1988.tb02883.x
Subject(s) - turgor pressure , phycomyces , growth rate , chemistry , stimulus (psychology) , biophysics , biology , psychology , geometry , mathematics , psychotherapist
— The turgor pressure of the stage 4b sporangiophore of Phycomyces blakesleeanus was continuously measured with a pressure probe before and during a period of increased elongational growth rate elicited by a step‐up in blue light fiuence rate (a positive light growth response) or by a double‐barrier stimulus (avoidance growth response). In these and other experiments it was found that a step‐up in turgor pressure between 0.02 and 0.05 MPa may elicit an increase in growth rate that is comparable to those of the light and avoidance growth responses. The results of the present work demonstrate that the turgor pressure does not increase during these growth responses, indicating that the increased growth rate is solely the result of altered cell wall mechanical properties. Furthermore, very small decreases in turgor pressure could be detected during the period of increased growth rate. This turgor pressure depression is predicted by the Growth Equations, and provides further support for the conclusion that the light and avoidance growth responses are solely the result of changes in cell wall mechanical properties.