Three-dimensional reconstruction of anomalous chloroplasts in transgenic ipt tobacco

Synková, Helena; Schnablová, Renáta; Polanská, Lenka; Hušák, M.; Siffel, P.; Vácha, František; Malbeck, Jiří; Macháčková, Ivana; Nebesářová, Jana

doi:10.1007/s00425-005-0119-6

Cited by 16 publications

(14 citation statements)

References 43 publications

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“…Previous studies have also observed changes to chloroplast structure following exposure to elevated cytokinins. For example, the formation of crystalloids or an ‘amoeboid-like’ morphology is characteristic of plastids in the leaves of stable transgenic tobacco overexpressing cytokinin synthesis genes [34,40]. Although we never observed crystalloids, the description of the ‘amoeboid-like’ plastid structure is reminiscent of our observations of multiple stromules emanating from a single plastid body.…”

Section: Discussionmentioning

confidence: 65%

Agrobacterium-derived cytokinin influences plastid morphology and starch accumulation in Nicotiana benthamiana during transient assays

et al. 2014

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BackgroundAgrobacterium tumefaciens-based transient assays have become a common tool for answering questions related to protein localization and gene expression in a cellular context. The use of these assays assumes that the transiently transformed cells are observed under relatively authentic physiological conditions and maintain ‘normal’ sub-cellular behaviour. Although this premise is widely accepted, the question of whether cellular organization and organelle morphology is altered in Agrobacterium-infiltrated cells has not been examined in detail. The first indications of an altered sub-cellular environment came from our observation that a common laboratory strain, GV3101(pMP90), caused a drastic increase in stromule frequency. Stromules, or ‘stroma-filled-tubules’ emanate from the surface of plastids and are sensitive to a variety of biotic and abiotic stresses. Starting from this observation, the goal of our experiments was to further characterize the changes to the cell resulting from short-term bacterial infestation, and to identify the factor responsible for eliciting these changes.ResultsUsing a protocol typical of transient assays we evaluated the impact of GV3101(pMP90) infiltration on chloroplast behaviour and morphology in Nicotiana benthamiana. Our experiments confirmed that GV3101(pMP90) consistently induces stromules and alters plastid position relative to the nucleus. These effects were found to be the result of strain-dependant secretion of cytokinin and its accumulation in the plant tissue. Bacterial production of the hormone was found to be dependant on the presence of a trans-zeatin synthase gene (tzs) located on the Ti plasmid of GV3101(pMP90). Bacteria-derived cytokinins were also correlated with changes to both soluble sugar level and starch accumulation.ConclusionAlthough we have chosen to focus on how transient Agrobacterium infestation alters plastid based parameters, these changes to the morphology and position of a single organelle, combined with the measured increases in sugar and starch content, suggest global changes to cell physiology. This indicates that cells visualized during transient assays may not be as ‘normal’ as was previously assumed. Our results suggest that the impact of the bacteria can be minimized by choosing Agrobacterium strains devoid of the tzs gene, but that the alterations to sub-cellular organization and cell carbohydrate status cannot be completely avoided using this strategy.

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Section: Discussionmentioning

confidence: 65%

Agrobacterium-derived cytokinin influences plastid morphology and starch accumulation in Nicotiana benthamiana during transient assays

et al. 2014

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“…On the contrary these plant hormones positively correlated with AR regeneration/final production effectiveness. Similarly, the presence of various anomalies in the ultrastructure of chloroplasts, from transgenic tobacco was the result of overproduction of endogenous CKs (Synkova et al 2006). Surprisingly, after LT the same type of CKs positively correlated with GR regeneration/final production, whereas trans isomers of Z and ZR seems to have positive effect on AR regeneration/final production effectiveness.…”

Section: Discussionmentioning

confidence: 95%

Identification of QTLs associated with albino plant formation and some new facts concerning green versus albino ratio determinants in triticale (×Triticosecale Wittm.) anther culture

et al. 2015

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High frequency of albino haploids/doubled haploids (DHs), regenerated in androgenic cultures is one of the major obstacles that limit incorporation of DHs technology into cereal breeding programs. Therefore, quantitative trait loci (QTL) associated with albino plant production in triticale anther cultures were analyzed using the population of 90 DH lines derived from F1 cross 'Saka 3006' 9 'Modus'. Composite interval mapping (CIM) and single marker analysis (SMA) in Windows QTL Cartographer ver 2.5 were used to localize the major QTLs. CIM method revealed seven QTLs with LOD scores between 2.9 and 5.6 on five chromosomes from B to R subgenomes (3B, 4B, 4R, 5R and 7R). Effects of all QTLs explained 8.3-17.6 % of the phenotypic variation and were confirmed by SMA analysis. Additionally SMA revealed another seven markers on chromosomes: 2AL.2BL, 3B, 2BS.6AL, 2RS.3R and 4R associated with QTL for albino plant regeneration (p \ 0.01). The additional experiment with ten DH lines varied significantly in their androgenic responsiveness was conducted to analyze the changes in the level of oxidative stress, antioxidative system activity and endogenous hormonal balance associated with androgenesis-inducing low temperature stress treatment (3 weeks at 4°C). The correlation analysis between albino/green plant regeneration ability and analyzed traits were performed by using Spearman Rank test (p B 0.05). Revealed associations may suggest that some level of oxidative stress is necessary for transition from a non-photosynthetic proplastids to the functional chloroplasts. On the other hand, the efficient antioxidative enzyme system and endogenous hormonal balance are also very important. Key message Fourteen chromosome regions were indicated to control albino plant formation during triticale anther culture. Additionally, reactive oxygen species (ROS) generation, antioxidative system activity and hormonal balance were discussed as determinants in androgenesis.

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“…Chl levels were also decreased in the shoot of the B-type arr1 arr10 arr12 triple mutant, affected in the majority of cytokininactivated responses during vegetative plant development (Argyros et al, 2008;Ishida et al, 2008). In addition, ectopic expression of the bacterial cytokinin biosynthetic ISOPENTENYLTRANSFERASE (ipt) gene increased Chl levels, enhanced photosynthetic activity, affected the ultrastructure of chloroplasts, and delayed leaf senescence (Synková et al, 2006;Procházková et al, 2008;Cortleven and Valcke, 2012).…”

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confidence: 99%

GROWTH REGULATING FACTOR5 Stimulates Arabidopsis Chloroplast Division, Photosynthesis, and Leaf Longevity

et al. 2015

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Arabidopsis (Arabidopsis thaliana) leaf development relies on subsequent phases of cell proliferation and cell expansion. During the proliferation phase, chloroplasts need to divide extensively, and during the transition from cell proliferation to expansion, they differentiate into photosynthetically active chloroplasts, providing the plant with energy. The transcription factor GROWTH REGULATING FACTOR5 (GRF5) promotes the duration of the cell proliferation period during leaf development. Here, it is shown that GRF5 also stimulates chloroplast division, resulting in a higher chloroplast number per cell with a concomitant increase in chlorophyll levels in 35S:GRF5 leaves, which can sustain higher rates of photosynthesis. Moreover, 35S:GRF5 plants show delayed leaf senescence and are more tolerant for growth on nitrogen-depleted medium. Cytokinins also stimulate leaf growth in part by extending the cell proliferation phase, simultaneously delaying the onset of the cell expansion phase. In addition, cytokinins are known to be involved in chloroplast development, nitrogen signaling, and senescence. Evidence is provided that GRF5 and cytokinins synergistically enhance cell division and chlorophyll retention after darkinduced senescence, which suggests that they also cooperate to stimulate chloroplast division and nitrogen assimilation. Taken together with the increased leaf size, ectopic expression of GRF5 has great potential to improve plant productivity.

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Three-dimensional reconstruction of anomalous chloroplasts in transgenic ipt tobacco

Cited by 16 publications

References 43 publications

Agrobacterium-derived cytokinin influences plastid morphology and starch accumulation in Nicotiana benthamiana during transient assays

Agrobacterium-derived cytokinin influences plastid morphology and starch accumulation in Nicotiana benthamiana during transient assays

Identification of QTLs associated with albino plant formation and some new facts concerning green versus albino ratio determinants in triticale (×Triticosecale Wittm.) anther culture

GROWTH REGULATING FACTOR5 Stimulates Arabidopsis Chloroplast Division, Photosynthesis, and Leaf Longevity

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