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Background: In rice, the cortex and outer tissues play a key role in submergence tolerance. The cortex differentiates into aerenchyma, which are air-containing cavities that allow the flow of oxygen from shoots to roots, whereas exodermis suberification and sclerenchyma lignification limit oxygen loss from the mature parts of roots by forming a barrier to root oxygen loss (ROL). The genes and their networks involved in the cellular identity and differentiation of these tissues remain poorly understood. Identification and characterization of key regulators of aerenchyma and ROL barrier formation require determination of the specific expression profiles of these tissues. Results: We optimized an approach combining laser microdissection (LM) and droplet digital RT-PCR (ddRT-PCR) for high-throughput identification of tissue-specific expression profiles. The developed protocol enables rapid (within 3 days) extraction of high-quality RNA from root tissues with a low contamination rate. We also demonstrated the possibility of extracting RNAs from paraffin blocks stored at 4 °C without any loss of quality. We included a detailed troubleshooting guide that should allow future users to adapt the proposed protocol to other tissues and/or species. We demonstrated that our protocol, which combines LM with ddRT-PCR, can be used as a complementary tool to in situ hybridization for tissue-specific characterization of gene expression even with a low RNA concentration input. We illustrated the efficiency of the proposed approach by validating three of four potential tissue-specific candidate genes detailed in the RiceXpro database. Conclusion: The detailed protocol and the critical steps required to optimize its use for other species will democratize tissue-specific transcriptome approaches combining LM with ddRT-PCR for analyses of plants.

Background: In rice, the cortex and outer tissues play a key role in submergence tolerance. The cortex differentiates into aerenchyma, which are air-containing cavities that allow the flow of oxygen from shoots to roots, whereas exodermis suberification and sclerenchyma lignification limit oxygen loss from the mature parts of roots by forming a barrier to root oxygen loss (ROL). The genes and their networks involved in the cellular identity and differentiation of these tissues remain poorly understood. Identification and characterization of key regulators of aerenchyma and ROL barrier formation require determination of the specific expression profiles of these tissues. Results: We optimized an approach combining laser microdissection (LM) and droplet digital RT-PCR (ddRT-PCR) for high-throughput identification of tissue-specific expression profiles. The developed protocol enables rapid (within 3 days) extraction of high-quality RNA from root tissues with a low contamination rate. We also demonstrated the possibility of extracting RNAs from paraffin blocks stored at 4 °C without any loss of quality. We included a detailed troubleshooting guide that should allow future users to adapt the proposed protocol to other tissues and/or species. We demonstrated that our protocol, which combines LM with ddRT-PCR, can be used as a complementary tool to in situ hybridization for tissue-specific characterization of gene expression even with a low RNA concentration input. We illustrated the efficiency of the proposed approach by validating three of four potential tissue-specific candidate genes detailed in the RiceXpro database. Conclusion: The detailed protocol and the critical steps required to optimize its use for other species will democratize tissue-specific transcriptome approaches combining LM with ddRT-PCR for analyses of plants.

Plant root development is highly responsive both to changes in nitrate availability and beneficial microorganisms in the rhizosphere. We previously showed that Phyllobacterium brassicacearum STM196, a plant growth-promoting rhizobacteria strain isolated from rapeseed roots, alleviates the inhibition exerted by high nitrate supply on lateral root growth. Since soil-borne bacteria can produce IAA and since this plant hormone may be implicated in the high nitrate-dependent control of lateral root development, we investigated its role in the root development response of Arabidopsis thaliana to STM196. Inoculation with STM196 resulted in a 50% increase of lateral root growth in Arabidopsis wild-type seedlings. This effect was completely abolished in aux1 and axr1 mutants, altered in IAA transport and signaling, respectively, indicating that these pathways are required. The STM196 strain, however, appeared to be a very low IAA producer when compared with the high-IAA-producing Azospirillum brasilense sp245 strain and its low-IAA-producing ipdc mutant. Consistent with the hypothesis that STM196 does not release significant amounts of IAA to the host roots, inoculation with this strain failed to increase root IAA content. Inoculation with STM196 led to increased expression levels of several IAA biosynthesis genes in shoots, increased Trp concentration in shoots, and increased auxin-dependent GUS staining in the root apices of DR5::GUS transgenic plants. All together, our results suggest that STM196 inoculation triggers changes in IAA distribution and homeostasis independently from IAA release by the bacteria., Times Cited: 6 6

Cet ouvrage, clair et pédagogique, fait le point sur les méthodes utilisées en amélioration des plantes ces dernières années. Il rappelle tout d’abord les principes généraux et les méthodes de génétique et d’amélioration des plantes. Il propose ensuite cinquante fiches de présentation de plantes cultivées. Pour chaque plante présentée : une synthèse sur l’histoire de l’espèce et les innovations marquantes en matière de création variétale (principales étapes de l’amélioration génétique, perspectives à envisager, données sur l’inscription et la protection des variétés), des illustrations de la plante entière et des produits de la récolte.Cet ouvrage s'adresse aux enseignants, aux étudiants, aux professionnels des semences et à toute personne qui s'intéresse à l'amélioration des plantes.

Cet ouvrage, clair et pédagogique, fait le point sur les méthodes utilisées en amélioration des plantes ces dernières années. Il rappelle tout d’abord les principes généraux et les méthodes de génétique et d’amélioration des plantes. Il propose ensuite cinquante fiches de présentation de plantes cultivées. Pour chaque plante présentée : une synthèse sur l’histoire de l’espèce et les innovations marquantes en matière de création variétale (principales étapes de l’amélioration génétique, perspectives à envisager, données sur l’inscription et la protection des variétés), des illustrations de la plante entière et des produits de la récolte.Cet ouvrage s'adresse aux enseignants, aux étudiants, aux professionnels des semences et à toute personne qui s'intéresse à l'amélioration des plantes.

Cet ouvrage, clair et pédagogique, fait le point sur les méthodes utilisées en amélioration des plantes ces dernières années. Il rappelle tout d’abord les principes généraux et les méthodes de génétique et d’amélioration des plantes. Il propose ensuite cinquante fiches de présentation de plantes cultivées. Pour chaque plante présentée : une synthèse sur l’histoire de l’espèce et les innovations marquantes en matière de création variétale (principales étapes de l’amélioration génétique, perspectives à envisager, données sur l’inscription et la protection des variétés), des illustrations de la plante entière et des produits de la récolte.Cet ouvrage s'adresse aux enseignants, aux étudiants, aux professionnels des semences et à toute personne qui s'intéresse à l'amélioration des plantes.

The maize abscisic acid (ABA)-responsive gene rab28 has been shown to be ABA-inducible in embryos and vegetative tissues, expression being mostly restricted to vascular elements during late embryogenesis. In the course of an expressed sequence tags (ESTs) programme, we have isolated an Arabidopsis thaliana gene, Atrab28, encoding the orthologue of maize rab28. The Atrab28 cDNA is 1090 bp long, including a poly(A)+ stretch, and encodes a polypeptide of 262 amino acids. Atrab28 antibody against the recombinant protein recognizes a polipeptide of about 30 kDa and pI 6, in close agreement with the predicted molecular mass and pI. As for maize rab28, expression studies with Atrab28 revealed high specificity for embryo tissues, transcription being stimulated by the transcriptional activator abi3. In contrast, Atrab28 was not induced in vegetative tissues by ABA, osmotic stress or dehydration. The expression of Atrab28 mRNA and the accumulation of Atrab28 protein was largely restricted to provascular tissues of mature embryos and in the seed coat outer tegument and embryo and silique epidermis, as revealed by in situ hybridization and immunocytochemistry with anti-Atrab28 antibodies.