Identification of genes related to germination in aged maize seed by screening natural variability

Ageing reduces vigour and viability in maize inbred lines due to non-heritable degenerative changes. Besides non-heritable genetic changes due to chromosome aberrations and damage in the DNA sequence, heritable changes during maize conservation have been reported. Genetic variability among aged seeds of inbred lines could be used for association studies with seed germination. The objective of this study was to identify genes related to germination in aged seeds. The sweet corn inbred line P39 and the field corn inbred line EP44 were used as plant material. Bulks of living and dead seeds after 20 and 22 years of storage were compared by using simple sequence repeats (SSRs) and, when the bulks differed for a marker, the individual grains were genotyped. Differences between dead and living seeds could be explained by residual variability, spontaneous mutation, or ageing. Variability was larger for chromosome 7 than for other chromosomes, and for distal than for proximal markers, suggesting some relationships between position in the genome and viability in aged seed. Polymorphic SSRs between living and dead seeds were found in six known genes, including pathogenesis-related protein 2, superoxide dismutase 4, catalase 3, opaque endosperm 2, and metallothionein1 that were related to germination, along with golden plant 2. In addition, five novel candidate genes have been identified; three of them could be involved in resistance to diseases, one in detoxification of electrophillic compounds, and another in transcription regulation. Therefore, genetic variability among aged seeds of inbreds was useful for preliminary association analysis to identify candidate genes

Accompagner la démarche de management stratégique de l’exploitation agricole

Développer la démarche de management stratégique dans les exploitations agricoles est une façon d’améliorer leurs performances dans le contexte actuel de l’agriculture. Les auteurs proposent un itinéraire méthodologique qui vise à accompagner les exploitants agricoles dans la construction de stratégies et dans leur traduction opérationnelle. Structuré en trois étapes, il aide à organiser la réflexion autour de la stratégie, puis à la formaliser, pour ensuite la piloter grâce à un tableau de bord stratégique. Le lien entre ces trois étapes est assuré par la construction d’une carte causale. Cet itinéraire a été construit dans le cadre du programme de recherche-action PerfEA avec des établissements publics locaux d’enseignement agricole. L’itinéraire s’adresse à tout type d’exploitation agricole et sa mise en œuvre nécessite la présence d’un conseiller.Strategic management is a relevant approach to support farmers in managing their farm and in coping with the current agricultural challenges. In this article we propose a methodological route which aims at enabling farmers to design their strategy and to implement them. The route is organized along three steps: it helps to organize the strategic thinking; to formalize the strategy by defining priorities and strategic lines; to draw up a strategic monitoring plan (the balanced scorecard). The link between the different steps is provided by the design of a causal mapping. This methodological route was built within an action research project entitled PerfEA (Global Performance for Farm) including farms belonging to public training schools. It suits all kind of farms and requires an agricultural adviser to accompany farmers in the design process of the strategy and its implementation

Tomato: a crop species amenable to improvement by cellular and molecular methods

Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures. In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.

Triticum durum metallothionein: isolation of the gene and structural characterization of the protein using solution scattering and molecular modeling

A novel gene sequence, with two exons and one intron, encoding a metallothionein (MT) has been identified in durum wheat Triticum durum cv. Balcali85 genomic DNA. Multiple alignment analyses on the cDNA and the translated protein sequences showed that T. durum MT (dMT) can be classified as a type 1 MT. dMT has three Cys-X-Cys motifs in each of the N- and C-terminal domains and a 42-residue-long hinge region devoid of cysteines. dMT was overexpressed in Escherichia coli as a fusion protein (GSTdMT), and bacteria expressing the fusion protein showed increased tolerance to cadmium in the growth medium compared with controls. Purified GSTdMT was characterized by SDS- and native-PAGE, size exclusion chromatography, and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. It was shown that the recombinant protein binds 4 ± 1 mol of cadmium/mol of protein and has a high tendency to form stable oligomeric structures. The structure of GSTdMT and dMT was investigated by synchrotron x-ray solution scattering and computational methods. X-ray scattering measurements indicated a strong tendency for GSTdMT to form dimers and trimers in solution and yielded structural models that were compatible with a stable dimeric form in which dMT had an extended conformation. Results of homology modeling and ab initio solution scattering approaches produced an elongated dMT structure with a long central hinge region. The predicted model and those obtained from x-ray scattering are in agreement and suggest that dMT may be involved in functions other than metal detoxification

Plant-inducible virulence promoter of the Agrobacterium tumefaciens Ti plasmid

Agrobacterium tumefaciens is the causative agent of crown gall, a plant tumour that can arise on most species of dicotyledonous plants. The tumour-inducing capacity of the bacterium requires the presence of a large plasmid, designated the Ti plasmid, which itself contains two regions essential for tumour formation-the T(umour)-region and the Vir(ulence)-region. The T-region is transferred to plant cells by an unknown mechanism, and becomes stably integrated into the plant genome. The Vir-region has been identified by transposon mutagenesis, but the DNA of this region has never been detected in tumour lines. However, trans-complementation of Vir mutants indicates that genes of the Vir-region are functional in the bacterium. Moreover, the Vir- and T-regions can be physically separated in A. tumefaciens without loss of tumour-inducing capacity. Seven loci, designated virA-F and virO, have been identified in the Vir-region of the octopine Ti plasmid, but their functions are unknown. As virC mutants in the octopine-type plasmid pTiB6 are invariably avirulent in tests on various plant species, this gene seems to be essential for virulence and we are studying it in detail. We report here that the promoter of virC shows no detectable activity in A. tumefaciens and Escherichia coli K-12 grown in standard medium, but that its activity is induced by a plant product.

Sceaux des archives communales d'Ussel. Catalogue rédigé par Jean-Loup le Maître (Ussel ; Musée du pays d'Ussel ; Paris : De Boccard, 1982, in-8°, 64 pages illustrées [Mémoires et documents sur le Bas-Limousin publiés par le musée du pays d'Ussel])

De Framond Martin. Sceaux des archives communales d'Ussel. Catalogue rédigé par Jean-Loup le Maître (Ussel ; Musée du pays d'Ussel ; Paris : De Boccard, 1982, in-8°, 64 pages illustrées [Mémoires et documents sur le Bas-Limousin publiés par le musée du pays d'Ussel]). In: Bibliothèque de l'école des chartes. 1983, tome 141, livraison 1. p. 178

Yves Soulingeas (1948-2004)

Framond Martin de. Yves Soulingeas (1948-2004). In: Bibliothèque de l'école des chartes. 2004, tome 162, livraison 2. pp. 664-667