Large impact of the apoplast on somatic embryogenesis in Cyclamen persicum offers possibilities for improved developmental control in vitro.
BACKGROUND
Clonal propagation is highly desired especially for valuable horticultural crops. The method with the potentially highest multiplication rate is regeneration via somatic embryogenesis. However, this mode of propagation is often hampered by the occurrence of developmental aberrations and non-embryogenic callus. Therefore, the developmental process of somatic embryogenesis was analysed in the ornamental crop Cyclamen persicum by expression profiling, comparing different developmental stages of embryogenic cell cultures, zygotic vs. somatic embryos and embryogenic vs. non-embryogenic cell cultures.


RESULTS
The analysis was based on a cDNA microarray representing 1,216 transcripts and was exemplarily validated by realtime PCR. For this purpose relative transcript abundances of homologues of a putative receptor kinase, two different glutathione S-transferases (GST), a xyloglucan endotransglycosylase (XET) and a peroxidase (POX) were quantitatively measured by realtime PCR for three different comparisons. In total, 417 genes were found to be differentially expressed. Gene Ontology annotation revealed that transcripts coding for enzymes that are active in the extracellular compartment (apoplast) were significantly overrepresented in several comparisons. The expression profiling results are underpinned by thorough histological analyses of somatic and zygotic embryos.


CONCLUSIONS
The putative underlying physiological processes are discussed and hypotheses on improvement of the protocol for in vitro somatic embryogenesis in Cyclamen persicum are deduced. A set of physiological markers is proposed for efficient molecular control of the process of somatic embryogenesis in C. persicum. The general suitability of expression profiling for the development and improvement of micropropagation methods is discussed.
Hoenemann
Claudia
C
Leibniz-Institute of Vegetable and Ornamental Crops (IGZ), Department Plant Propagation, Kuehnhaeuser Strasse 101, 99189 Erfurt, Germany. Hohe@erfurt.igzev.de
Richardt
Sandra
S
Krüger
Katja
K
Zimmer
Andreas D
AD
Hohe
Annette
A
Rensing
Stefan A
SA
D002460:Cell Line; D003470:Culture Media / Q000494:pharmacology; D031824:Cyclamen / Q000187:drug effects / Q000196:embryology* / Q000235:genetics*; D047108:Embryonic Development / Q000187:drug effects / Q000235:genetics*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D020411:Oligonucleotide Array Sequence Analysis; D025341:Principal Component Analysis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000166:cytology / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D013194:Staining and Labeling; D013997:Time Factors; D046509:Tissue Culture Techniques; D015053:Zygote / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D003470:Culture Media; D012333:RNA, Messenger