TY - JOUR
T1 - The mechanism by which an asymmetric distribution of plant growth hormone is attained
AU - Bandurski, Robert S.
AU - Schulze, Aga
AU - Jensen, Philip
AU - Desrosiers, Mark
AU - Epel, Bernard
AU - Kowalczyk, Stanley
N1 - Funding Information:
Report of work supported wholly or in part by the Life Science Division of the National Aeronautics and Space Administration, Space Biology, NASA-NAGW-97 and NAG 10-0067, and Flight Program , NAG 2-362, and by the Cellular Biology and Biochemistry Section of the National Science Foundation, DCB-8805 148. We are indebted to Dr. Robert Warmbrodt for the EM of Fig. 3.
PY - 1992
Y1 - 1992
N2 - Zea mays (sweet corn) seedlings attain an asymmetric distribution of the growth hormone indole-3-acetic acid (IAA) within 3 minutes following a gravity stimulus. Both free and esterified IAA (that is total IAA) accumulate to a greater extent in the lower half of the mesocotyl cortex of a horizontally placed seedling than in the upper half. Thus, changes in the ratio of free IAA to ester IAA cannot account for the asymmetric distribution. Our studies demonstrate there is no de novo synthesis of IAA in young seedlings. We conclude that asymmetric IAA distribution is attained by a gravity-induced, potential-regulated gating of the movement of IAA from kernel to shoot and from stele to cortex. As a working theory, which we call the Potential Gating Theory, we propose that perturbation of the plant's bioelectric field, induced by gravity, causes opening and closing of transport channels in the plasmodesmata connecting the vascular stele to the surrounding cortical tissues. This results in asymmetric growth hormone distribution which results in the asymmetric growth characteristic of the gravitropic response.
AB - Zea mays (sweet corn) seedlings attain an asymmetric distribution of the growth hormone indole-3-acetic acid (IAA) within 3 minutes following a gravity stimulus. Both free and esterified IAA (that is total IAA) accumulate to a greater extent in the lower half of the mesocotyl cortex of a horizontally placed seedling than in the upper half. Thus, changes in the ratio of free IAA to ester IAA cannot account for the asymmetric distribution. Our studies demonstrate there is no de novo synthesis of IAA in young seedlings. We conclude that asymmetric IAA distribution is attained by a gravity-induced, potential-regulated gating of the movement of IAA from kernel to shoot and from stele to cortex. As a working theory, which we call the Potential Gating Theory, we propose that perturbation of the plant's bioelectric field, induced by gravity, causes opening and closing of transport channels in the plasmodesmata connecting the vascular stele to the surrounding cortical tissues. This results in asymmetric growth hormone distribution which results in the asymmetric growth characteristic of the gravitropic response.
UR - https://www.scopus.com/pages/publications/0027106122
U2 - 10.1016/0273-1177(92)90284-5
DO - 10.1016/0273-1177(92)90284-5
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AN - SCOPUS:0027106122
SN - 0273-1177
VL - 12
SP - 203
EP - 210
JO - Advances in Space Research
JF - Advances in Space Research
IS - 1
ER -