Interaction of growth-determining systems with gravity.
The experiments have been carried out with lettuce shoots on board the Salyut-7 orbital station the Kosmos-1667 biological satellite and under ground conditions at 180 degrees plant inversion. By means of the centrifuge Biogravistat-1M the threshold value of gravitational sensitivity of lettuce shoots has been determined on board the Salyut-7 station. It was found to be equal to 2.9 x 10(-3)g for hypocotyls and 1.5 x 10(-4)g for roots. The following results have been received in the experiment performed on board the Kosmos-1667 satellite: a) under microgravity the proliferation of the meristem cells and the growth of roots did not differ from the control; b) the growth of hypocotyls in length was significantly enhanced in microgravity; c) under microgravity transverse growth of hypocotyls (increase in cross sectional area) was significantly increased due to enhancement of cortical parenchyma cell growth. At 180 degrees inversion in Earth's gravity root extension growth and rate of cell division in the root apical meristem were decreased. The determination of DNA-fuchsin value in the nuclei of the cell root apexes showed that inversion affected processes of the cell cycle preceding cytokinesis.
Merkys
A
A
Institute of Botany of the Academy of Sciences of the Lithuanian SSR, Vilnius, USSR.
Laurinavicius
R
R
Bendoraityte
D
D
Svegzdiene
D
D
Rupainiene
O
O
D002455:Cell Division; D002498:Centrifugation; D018744:DNA, Plant; D006112:Gravitation; D018522:Gravitropism / Q000235:genetics / Q000502:physiology*; D018546:Hypocotyl / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D018545:Lactuca / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D008938:Mitosis / Q000502:physiology; D018517:Plant Roots / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D018520:Plant Shoots / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D013026:Space Flight; D014893:Weightlessness
D018744:DNA, Plant