Organogenic nodule development in hop (Humulus lupulus L.): transcript and metabolic responses.
BACKGROUND
Hop (Humulus lupulus L.) is an economically important plant forming organogenic nodules which can be used for genetic transformation and micropropagation. We are interested in the mechanisms underlying reprogramming of cells through stress and hormone treatments.


RESULTS
An integrated molecular and metabolomic approach was used to investigate global gene expression and metabolic responses during development of hop's organogenic nodules. Transcript profiling using a 3,324-cDNA clone array revealed differential regulation of 133 unigenes, classified into 11 functional categories. Several pathways seem to be determinant in organogenic nodule formation, namely defense and stress response, sugar and lipid metabolism, synthesis of secondary metabolites and hormone signaling. Metabolic profiling using 1H NMR spectroscopy associated to two-dimensional techniques showed the importance of metabolites related to oxidative stress response, lipid and sugar metabolism and secondary metabolism in organogenic nodule formation.


CONCLUSIONS
The expression profile of genes pivotal for energy metabolism, together with metabolites profile, suggested that these morphogenic structures gain energy through a heterotrophic, transport-dependent and sugar-degrading anaerobic metabolism. Polyamines and auxins are likely to be involved in the regulation of expression of many genes related to organogenic nodule formation. These results represent substantial progress toward a better understanding of this complex developmental program and reveal novel information regarding morphogenesis in plants.
Fortes
Ana M
AM
ICAT, FCUL, University of Lisbon, Campo Grande, 1749-016 Lisbon, Portugal. margafortes@yahoo.com
Santos
Filipa
F
Choi
Young H
YH
Silva
Marta S
MS
Figueiredo
Andreia
A
Sousa
Lisete
L
Pessoa
Fernando
F
Santos
Bartolomeu A
BA
Sebastiana
Mónica
M
Palme
Klaus
K
Malhó
Rui
R
Verpoorte
Rob
R
Pais
Maria S
MS
D020869:Gene Expression Profiling; D017343:Genes, Plant; D027582:Humulus / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic
D010940:Plant Proteins