Apical meristem
Apical meristems ( lat. : Apex = apex tip; gr. : Merizein share =) or Scheitelmeristeme are capable of dividing meristems of plants . They are present at the respective tip of the root and shoot and occur there together with the primary meristem. The task of this tissue is the production of shoot and root cells.
shape
Apical meristems are cone-shaped in most of the higher plants. In rosette plants there are also flattened or convex apical meristems, in palm trees there are large plate-shaped, so-called apex pits. Apical apical meristems of the shoot are often enveloped by leaf primordia , while basal apical meristems at the root tips are protected by the root cap .
composition
In the area of the apical meristems are the primary meristems in which the actual cell division takes place. The apical meristem differs from permanent tissue in type and function because, in contrast to permanent tissue, it consists of undifferentiated cells, has relatively thin cell walls and has only slight cell sap vacuoles .
function
Like all other meristems, the apical meristem belongs to the embryonic tissue, which is comparable to the stem cells of animals. The cells of the apical meristem are particularly easy to divide and play a key role in the growth of the plant. The formation of new organs (for example leaves and side shoots) is made possible by dividable stem cells (initials) that are retained in the vertex meristem.
Use in plant tissue culture
In the context of in-vitro culture, the apical meristem of the shoot is used as an explant for direct cloning of the plant , especially when herbaceous plants are propagated . In the context of the meristem culture , only the apical meristem of the shoot is used in the strict sense. This is technically very complex and is rarely used as a method of plant tissue culture . In sprout tip culture, which is colloquially often classified under the term meristem culture, the surrounding leaf primordia and a larger amount of surrounding tissue such as leaf systems or shoots are used in addition to the apical meristem. This promotes the additional formation of adventitious organs , here especially adventitious shoots.
literature
- Andreas Bresinsky , Christian Körner , Joachim W. Kadereit , Gunther Neuhaus , Uwe Sonnewald : Strasburger - textbook of botany. Founded by E. Strasburger. 36th edition. Spectrum Akademischer Verlag, Heidelberg 2008, ISBN 978-3-8274-1455-7 .
- Helmut Plattner, Joachim Hentschel: Cell Biology. 3rd, revised edition. Thieme Georg Verlag, Stuttgart 2006, ISBN 3-580-63690-1 .
- Dieter Hess : Plant biotechnology. An introduction. UTB Ulmer Verlag, Stuttgart 1992, ISBN 3-8252-8060-8 .
Individual evidence
- ↑ Heinz Jansen, Elmar Bachthaler, Erich Fölster, Hans-Christoph Scharpf: Horticultural plant production. Basics of growing under glass and plastics. 3rd edition, Ulmer Verlag, Stuttgart 1997. pp. 255 ff.