The role of actin isoforms in somatic embryogenesis in Norway spruce.
BACKGROUND
Somatic embryogenesis in spruce is a process of high importance for biotechnology, yet it comprises of orchestrated series of events whose cellular and molecular details are not well understood. In this study, we examined the role of actin cytoskeleton during somatic embryogenesis in Norway spruce line AFO 541 by means of anti-actin drugs.


RESULTS
Application of low doses (50-100 nM) of latrunculin B (Lat B) during the maturation of somatic embryos predominantly killed suspensor cells while leaving the cells in meristematic centres alive, indicating differential sensitivity of actin in the two cell types. The treatment resulted in faster development of more advanced embryos into mature somatic embryos and elimination of insufficiently developed ones. In searching for the cause of the differential actin sensitivity of the two cell types, we analysed the composition of actin isoforms in the culture and isolated four spruce actin genes. Analysis of their expression during embryo maturation revealed that one actin isoform was expressed constitutively in both cell types, whereas three actin isoforms were expressed predominantly in suspensor cells and their expression declined during the maturation. The expression decline was greatly enhanced by Lat B treatment. Sequence analysis revealed amino-acid substitutions in the Lat B-binding site in one of the suspensor-specific actin isoforms, which may result in a different binding affinity for Lat B.


CONCLUSIONS
We show that manipulating actin in specific cell types in somatic embryos using Lat B treatment accelerated and even synchronized the development of somatic embryos and may be of practical use in biotechnology.
Schwarzerová
Katerina
K
Charles University in Prague, Faculty of Science, Department of Plant Physiology, Vinicná 5, CZ 12844 Prague 2, Czech Republic.
Vondráková
Zuzana
Z
Fischer
Lukás
L
Boríková
Petra
P
Bellinvia
Erica
E
Eliásová
Katerina
K
Havelková
Lenka
L
Fiserová
Jindriska
J
Vágner
Martin
M
Opatrný
Zdenek
Z
D000199:Actins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019943:Amino Acid Substitution; D001665:Binding Sites; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D010802:Phylogeny; D028222:Picea / Q000196:embryology / Q000254:growth & development*; D020033:Protein Isoforms / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics; D016415:Sequence Alignment; D053778:Thiazolidines / Q000494:pharmacology; D046509:Tissue Culture Techniques
D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D020033:Protein Isoforms; D018749:RNA, Plant; D053778:Thiazolidines; C037068:latrunculin B