Biogenesis of protein bodies during vicilin accumulation in Medicago truncatula immature seeds

BACKGROUND: Grain legumes play a worldwide role as a source of plant proteins for feed and food. In the model legume Medicago truncatula, the organisation of protein storage vacuoles (PSV) in maturing seeds remains unknown. FINDINGS: The sub-cellular events accompanying the accumulation of vicilin (globulin7S) were analysed during seed mid-maturation. Immuno-detection of vicilin in light microscopy, allowed a semi-quantitative assessment of the protein body complement. The identified populations of vicilin-containing protein bodies are distinguished by their number and size which allowed to propose a model of their biogenesis. Two distributions were detected, enabling a separation of their processing at early and mid maturation stages. The largest protein bodies, at 16 and 20 days after pollination (DAP), were formed by the fusion of small bodies. They have probably attained their final size and correspond to mature vicilin aggregations. Electron microscopic observations revealed the association of the dense protein bodies with rough endoplasmic reticulum. The presence of a ribosome layer surrounding protein bodies, would support an endoplasmic reticulum–vacuole trafficking pathway. CONCLUSIONS: The stastistic analysis may be useful for screening mutations of candidate genes governing protein content. The definitive evidence for an ER-storage vacuole pathway corresponds to a challenge, for the storage of post-translationally unstable proteins. It was proposed for the accumulation of one class of storage protein, the vicilins. This alternative pathway is a matter of controversy in dicotyledonous seeds

The role of the pod in seed development: strategies for manipulating yield

Pods play a key role in encapsulating the developing seeds and protecting them from pests and pathogens. In addition to this protective function, it has been shown that the photosynthetically active pod wall contributes assimilates and nutrients to fuel seed growth. Recent work has revealed that signals originating from the pod may also act to coordinate grain filling and regulate the reallocation of reserves from damaged seeds to those that have retained viability. In this review we consider the evidence that pods can regulate seed growth and maturation, particularly in members of the Brassicaceae family, and explore how the timing and duration of pod development might be manipulated to enhance either the quantity of crop yield or its nutritional properties

Architecture fonctionnelle du noyau : Une alternative pour l’étude de l’endoréplication dans la graine

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Architecture fonctionnelle du noyau : Une alternative pour l’étude de l’endoréplication dans la graine

National audienc

Assessing chromosome modifications in GM plants

International audienc

Genomic in situ hybridization (GISH) discriminates between the A and the B genomes in diploid and tetraploid <i>Setaria</i> species

Genomic in situ hybridization (GISH) was used to investigate genomic relationships between different Setaria species of the foxtail millet gene pool (S. italica) and one interspecific F1 hybrid. The GISH patterns obtained on the two diploid species S. viridis (genome A) and S. adhaerans (genome B), and on their F1 hybrid showed clear differentiation between these two genomes except at the nucleolar organizing regions. Similar GISH patterns allowed differentiation of S. italica from S. adhaerans. However, GISH patterns did not distinguish between the genomes of S. italica and its putative wild ancestor S. viridis. GISH was also applied to polyploid Setaria species and enabled confirmation of the assumed allotetraploid nature of S. faberii and demonstration that both S. verticillata and S. verticillata var. ambigua were also allotetraploids. All these tetraploid species contained two sets of 18 chromosomes each, one from genome A and the other from genome B. Only one polyploid species, S. pumila, was shown to bear an unknown genomic composition that is not closely related either to genome A or to genome B.Key words: Setaria, genomic in situ hybridization, genome analysis. </jats:p

Phylogenetic and genomic relationships in Setaria italica and its close relatives based on the molecular diversity and chromosomal organization of 5S and 18S-5,8S-25S rDNA genes

International audienc

Distribution and chromosomal organization of 18S-5.8S-25S and 5S rDNA in Petunia species

We have analyzed the interspecific variation of the 5S rDNA spacer by the polymerase chain reaction in seven Petunia species. The species studied could be separated into two groups with regard to the size of the amplified 5S rDNA variants: one group, with a 460-bp repeat unit, including P linearis (2n = 18) and P integrifolia (2n = 14) and the second group, with a 350-bp repeat unit, including all the other wild species (2n = 14) studied and the P hybrida lines. The amplified fragments have been cloned, and used in FISH experiments to determine the number and the location of the 5S rDNA units. The chromosomal organization of the 5S rDNA enabled us to distinguish a group of coloured flowered species with one locus adjacent to the major 18S-5.8S-25S rDNA locus on chromosome II, and a group of white flowered species with an additional locus in the centromeric region of a metacentric chromosome (IV/VII). FISH analysis also revealed four hybridization sites of 18S-5.8S-25S rDNA in the majority of the Petunia species studied. Only P linearis and P parviflora (2n = 18) showed two hybridization sites. The four sites of 18S-5.85-25S rDNA are transcriptionally active as shown by their expression pattern in interphase nuclei. Our FISH results combined with PCR amplification and RFLP studies of the rDNA clusters give a new insight into the phylogenetic relationships between wild species and the P hybrida lines.Distribution et organisation chromosomique des gènes ribosomiques 18S-5.8S-25S et 5S chez Petunia. Nous avons analysé la variation interspécifique de l'espaceur 5S ADNr par la tehnique d'amplification génique (PCR) dans sept espèces de Petunia. Les espèce étudiées peuvent être séparées en deux groupes suivant la taille des variants 5S ADNr amplifiés : un groupe avec une unité de répétition de 460 pb comprenant P linearis (2 n = 18) et P integrifolia (2 n = 14), et un deuxième groupe avec une unité de répétition de 350 pb comprenant toutes les autres espèces sauvages (2 n = 14) étudiées et les lignées de P hybrida. Les fragments amplifiés ont été clonés et ont servi de sondes pour l'hybridation in situ fluorescente afin de déterminer le nombre et la localisation des unités 5S. L'organisation chromosomique du 5S ADNr nous a permis de distinguer un groupe d'espèces à fleurs colorées avec un locus adjacent au locus majeur 18S-5.8S-25S ADNr du chromosome II et un groupe d'espèces à fleurs blanches avec un locus supplémentaire situé dans la région centromérique d'un chromosome métacentrique (IV/VII). L'hybridation in situ fluorescente a également révélé quatre sites d'hybridation pour le 18S-5.8S-25S ADNr dans la majorité des espèces de Petunia étudiées. Seuls P linearis et P parviflora (2 n = 18) ont montré deux sites d'hybridation. L'observation des pattern d'expression dans les noyaux interphasiques nous a permis de montrer que les quatre sites d'ADNr18S-5.8S-25S sont en activité de transcription. Les résultats obtenus en hybridation in situ fluorescente ainsi que les amplifications par PCR et les études RFLP des ADNr nous ont conduits à une nouvelle approche des relations phylogéniques entre les espèces sauvages et les lignées de P hybrida

Distribution and chromosomal organization of 18S-5.8S-25S and 5S rDNA in Petunia species

International audienc