- G. Engler (1)
- S.P.C. Groot (2)
- H.W.M. Hilhorst (1)
- D. Inze (1)
- S.E. Knopp (1)
- D. Kramer (1)
- K. Poucke van (1)
- D. Selmar (1)
- L. Veylder de (1)
Transient Occurrence of Seed Germination Processes during Coffee Post-harvest Treatment
Bytof, G. ; Knopp, S.E. ; Kramer, D. ; Breitenstein, B. ; Bergervoet, J.H.W. ; Groot, S.P.C. ; Selmar, D. - \ 2007
Annals of Botany 100 (2007)1. - ISSN 0305-7364 - p. 61 - 66.
beta-tubulin accumulation - tomato seeds - gene - expression - cucumber - quality - beans
Background and Aims: The chemical composition of green coffee and thus the final coffee quality are specifically determined by the mode of post-harvest treatment, i.e. the wet and dry processing. Recently, it was shown that metabolic processes, i.e. germination and, a slightly delayed stress-related metabolism are executed during the course of processing. The specific ambient conditions of either post-harvest treatment may influence differentially the extent and time course of these metabolic reactions; therefore, the incidence and intensity of germination processes in coffee seeds were analysed during processing. Methods: Expression of the germination-specific isocitrate lyase was monitored using competitive RT-PCRs analyses. Resumption of cell cycle activity and cell division were determined by flow cytometry, as well as by the abundance of ß-tubulin quantified by Western blot analyses. Key Results: The extent and the time courses of germination processes in coffee seeds differed significantly between wet and dry processed beans. The highest germination activity occurred 2 d after the onset of wet processing, whereas the corresponding maximum in the course of dry processing appeared about 1 week after the start of post harvest treatment. Conclusions: As recently shown, there are specific differences in the chemical composition of differentially processed coffee beans. It is concluded that these substantial differences are the consequence of the differential expression of germination processes, i.e. they are the result of differences in the corresponding metabolic activities. The coherence of germination-related metabolism and of expression-specific coffee qualities establishes the basis for a novel approach in coffee research. Key words: Coffea arabica, coffee processing
Hormonal control of seed development in gibberellin- and ABA-deficient tomato (Lycopersicon esculentum Mill. cv. Moneymaker) mutants
Castro, R.D. de; Hilhorst, H.W.M. - \ 2006
Plant Science 170 (2006)3. - ISSN 0168-9452 - p. 462 - 470.
beta-tubulin accumulation - abscisic-acid - gibberellin-deficient - arabidopsis-thaliana - plant embryogenesis - fruit-development - primary dormancy - sitiens mutant - germination - maize
Developing seeds of tomato gibberellin (GA)-deficient gib1 and abscisic acid (ABA)-deficient sitw mutants enabled us to analyze the role of GA in the regulation of embryo histo-differentiation, and the role of ABA in the regulation of maturation and quiescence. Our data show that DNA synthesis and mitotic microtubule arrays are markers for cell division activity and histo-differentiation during early embryogenesis. Cortical microtubular cytoskeleton alone is a marker for expansion growth during maturation, as seed and embryo gain dry weight and attain their final size. During this phase germinability, desiccation tolerance and dormancy are acquired, and a transient increase in ABA occurs, preceding the achievement of physiological maturity and subsequent quiescence. In the gib1 mutant embryo development was retarded in all parameters studied, except for a transient rise in ABA content. In the sitw mutant embryonic DNA synthesis activity was resumed upon completion of histo-differentiation, the microtubular cytoskeleton network was re-established during maturation and followed by viviparous germination. This suggests that ABA controls the suppression of these events during maturation and quiescence. Induction of full seed germinability, desiccation tolerance and dormancy was related to the completion of embryo histo-differentiation but was independent of the state of the microtubular cytoskeleton during maturation.
The role of the cell cycle machinery in resumption of postembryonic development
Barroco, R.M. ; Poucke, K. van; Bergervoet, J.H.W. ; Veylder, L. de; Groot, S.P.C. ; Inze, D. ; Engler, G. - \ 2005
Plant Physiology 137 (2005)1. - ISSN 0032-0889 - p. 127 - 140.
beta-tubulin accumulation - in-situ hybridization - arabidopsis-thaliana - tomato seeds - maize germination - dependent kinases - dna-replication - expression - division - plants
Cell cycle activity is required for plant growth and development, but its involvement in the early events that initiate seedling development remains to be clarified. We performed experiments aimed at understanding when cell cycle progression is activated during seed germination, and what its contribution is for proper seedling establishment. To this end, the spatial and temporal expression profiles of a large set of cell cycle control genes in germinating seeds of Arabidopsis (Arabidopsis thaliana) and white cabbage (Brassica oleracea) were analyzed. The in vivo behavior of the microtubular cytoskeleton was monitored during Arabidopsis seed germination. Flow cytometry of Arabidopsis germinating seeds indicated that DNA replication was mainly initiated at the onset of root protrusion, when germination reached its end. Expression analysis of cell cycle genes with mRNA in situ localization, -glucuronidase assays, and semiquantitative reverse transcription-polymerase chain reaction showed that transcription of most cell cycle genes was detected only after completion of germination. In vivo green fluorescent protein analysis of the microtubule cytoskeleton demonstrated that mitosis-specific microtubule arrays occurred only when the radicle had started to protrude, although the assembly of the microtubular cytoskeleton was promptly activated once germination was initiated. Thus, seed germination involves the synthesis and/or activation of a reduced number of core cell cycle proteins, which only trigger DNA replication, but is not sufficient to drive cells into mitosis. Mitotic divisions are observed only after the radicle has protruded and presumably rely on the de novo production of other cell cycle regulators