Flooding of the apoplast is a key factor in the development of hyperhydricity

The physiological disorder hyperhydricity occurs frequently in tissue culture and causes several morphological abnormalities such as thick, brittle, curled, and translucent leaves. It is well known that hyperhydric shoots are characterized by a high water content, but how this is related to the abnormalities is not clear. It was observed that water accumulated extensively in the apoplast of leaves of hyperhydric Arabidopsis seedlings and flooded apoplastic air spaces almost completely. In hyperhydric Arabidopsis seedlings, the volume of apoplastic air was reduced from 85% of the apoplast to only 15%. Similar results were obtained with hyperhydric shoots of statice. The elevated expression of hypoxia-responsive genes in hyperhydric seedlings showed that the water saturation of the apoplast decreased oxygen supply. This demonstrates a reduced gas exchange between the symplast and its surroundings, which will consequently lead to the accumulation of gases in the symplast, for example ethylene and methyl jasmonate. The impairment of gas exchange probably brings about the symptoms of hyperhydricity. Interestingly, stomatal aperture was reduced in hyperhydric plants, a previously reported response to injection of water into the apoplast. Closure of the stomata and the accumulation of water in the apoplast may be the reasons why seedlings with a low level of hyperhydricity showed improved acclimatization after planting into soil

Effect of changes in cell cycle gene expression on tomato fruit development

Contains fulltext : 94177.pdf (publisher's version ) (Open Access)Radboud Universiteit Nijmegen, 7 september 2012Promotores : Angenent, G.C., Mariani, C. Co-promotor : Maagd, R.A. de184 p

In vitro grown arabidopsis - salicylic acid

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Introducing Continuous Improvement in an R&D Facility : Action research in the pharmaceutical industry

Continuous Improvement processes are commonly used by many organizations facing competitive pressure. By implementing continuous incremental changes, it allows optimizing resources while maintaining flexibility. However, it requires significant resources and involvement from all levels of management, as well as field workers. Continuous Improvement is based on the study of processes and the identification of recurrent problems; therefore it is particularly adapted to manufacturing activities and other repetitive processes. R&D (Research and Development) activities are less repetitive and tend to be iterative, which make them more difficult to study. Yet these activities represent a strong competitive asset and an early mistake or misunderstanding might have a significant cost. The objective of this project was to study the deployment of Continuous Improvement for R&D processes through a literature review and a case study in the pharmaceutical industry. Action research has been the research method that has been employed; the particularity of this method is that the researcher participates actively to the studied change. It resulted in the identification of some characteristics that have to be taken into account in the deployment of improvement activities. First the culture is based on problem-solving, which increase the efficiency of data study and analytical method whilst formalization tools are less efficient, as well as performance indicators related to improvement activities. Besides, the need of customers (both internal and external) is difficult to define and is subject to evolution; this issue tends to be aggravated by a lack of communication. Moreover, development projects being unique and highly iterative, it is recommended to study processes at a more conceptual level, although no specific mapping tool seems particularly adapted. Finally, beside the study of general processes, the study of each individual project (project reviews) allows individual and collective learning. This project also propose a tool allowing the study of information flows between activities and teams in order to reduce mismatch between need and reality (and thus communication issues). This tool relies on the use of local SIPOC diagrams to represent activities and the mapping of flows between each of them

The cell size distribution of tomato fruit can be changed by overexpression of CDKA1

Tomato is one of the most cultivated vegetables in the world and an important ingredient of the human diet. Tomato breeders and growers face a continuous challenge of combining high quantity (production volume) with high quality (appearance, taste and perception for the consumers, processing quality for the processing industry). To improve the quality of tomato, it is important to understand the regulation of fruit development and of fruit cellular structure, which is in part determined by the sizes and numbers of cells within a tissue. The role of the cell cycle therein is poorly understood. Plant cyclin-dependent kinases (CDKs) are homologues of yeast cdc2, an important cell cycle regulator conserved throughout all eukaryotes. CDKA1 is constitutively expressed during the cell cycle and has dual functions in S- and M-phase progression. We have produced transgenic tomato plants with increased expression of CDKA1 under the control of the fruit-specific TPRP promoter, which despite a reduced number of seeds and diminished amount of jelly, developed fruits with weight and shape comparable to that of wild-type fruits. However, the phenotypic changes with regard to the pericarp thickness and placenta area were remarkable. Fruits of tomato plants with the highest expression of CDKA1 had larger septa and columella (placenta), compared with wild-type fruits. Our data demonstrate the possibility of manipulating the ratio between cell division and expansion by changing the expression of a key cell cycle regulator and probably its activity with substantial effects on structural traits of the harvested fruit

Flooding of the apoplast is a key factor in the development of hyperhydricity

The physiological disorder hyperhydricity occurs frequently in tissue culture and causes several morphological abnormalities such as thick, brittle, curled, and translucent leaves. It is well known that hyperhydric shoots are characterized by a high water content, but how this is related to the abnormalities is not clear. It was observed that water accumulated extensively in the apoplast of leaves of hyperhydric Arabidopsis seedlings and flooded apoplastic air spaces almost completely. In hyperhydric Arabidopsis seedlings, the volume of apoplastic air was reduced from 85% of the apoplast to only 15%. Similar results were obtained with hyperhydric shoots of statice. The elevated expression of hypoxia-responsive genes in hyperhydric seedlings showed that the water saturation of the apoplast decreased oxygen supply. This demonstrates a reduced gas exchange between the symplast and its surroundings, which will consequently lead to the accumulation of gases in the symplast, for example ethylene and methyl jasmonate. The impairment of gas exchange probably brings about the symptoms of hyperhydricity. Interestingly, stomatal aperture was reduced in hyperhydric plants, a previously reported response to injection of water into the apoplast. Closure of the stomata and the accumulation of water in the apoplast may be the reasons why seedlings with a low level of hyperhydricity showed improved acclimatization after planting into soil