Protoplast: A Valuable Toolbox to Investigate Plant Stress Perception and Response

Plants are constantly facing abiotic and biotic stresses. To continue to thrive in their environment, they have developed many sophisticated mechanisms to perceive these stresses and provide an appropriate response. There are many ways to study these stress signals in plant, and among them, protoplasts appear to provide a unique experimental system. As plant cells devoid of cell wall, protoplasts allow observations at the individual cell level. They also offer a prime access to the plasma membrane and an original view on the inside of the cell. In this regard, protoplasts are particularly useful to address essential biological questions regarding stress response, such as protein signaling, ion fluxes, ROS production, and plasma membrane dynamics. Here, the tools associated with protoplasts to comprehend plant stress signaling are overviewed and their potential to decipher plant defense mechanisms is discussed

Metabolic Engineering of Yeast and Plants for the Production of the Biologically Active Hydroxystilbene, Resveratrol

Resveratrol, a stilbenic compound deriving from the phenyalanine/polymalonate route, being stilbene synthase the last and key enzyme of this pathway, recently has become the focus of a number of studies in medicine and plant physiology. Increased demand for this molecule for nutraceutical, cosmetic and possibly pharmaceutic uses, makes its production a necessity. In this context, the use of biotechnology through recombinant microorganisms and plants is particularly promising. Interesting results can indeed arise from the potential of genetically modified microorganisms as an alternative mechanism for producing resveratrol. Strategies used to tailoring yeast as they do not possess the genes that encode for the resveratrol pathway, will be described. On the other hand, most interest has centered in recent years, on STS gene transfer experiments from various origins to the genome of numerous plants. This work also presents a comprehensive review on plant molecular engineering with the STS gene, resulting in disease resistance against microorganisms and the enhancement of the antioxidant activities of several fruits in transgenic lines

MECANISMES DE DEFENSE DES PLANTES CONTRE LES AGENTS PATHOGENES (ETUDE DU PHENOMENE DE RESISTANCE LOCALE ACQUISE CHEZ LE TABAC)

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Modulation of Phytoalexin Biosynthesis in Engineered Plants for Disease Resistance

Phytoalexins are antimicrobial substances of low molecular weight produced by plants in response to infection or stress, which form part of their active defense mechanisms. Starting in the 1950’s, research on phytoalexins has begun with biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity as well as mechanisms of their synthesis and their catabolism by microorganisms. Elucidation of the biosynthesis of numerous phytoalexins has permitted the use of molecular biology tools for the exploration of the genes encoding enzymes of their synthesis pathways and their regulators. Genetic manipulation of phytoalexins has been investigated to increase the disease resistance of plants. The first example of a disease resistance resulting from foreign phytoalexin expression in a novel plant has concerned a phytoalexin from grapevine which was transferred to tobacco. Transformations were then operated to investigate the potential of other phytoalexin biosynthetic genes to confer resistance to pathogens. Unexpectedly, engineering phytoalexins for disease resistance in plants seem to have been limited to exploiting only a few phytoalexin biosynthetic genes, especially those encoding stilbenes and some isoflavonoids. Research has rather focused on indirect approaches which allow modulation of the accumulation of phytoalexin employing transcriptional regulators or components of upstream regulatory pathways. Genetic approaches using gain- or less-of functions in phytoalexin engineering together with modulation of phytoalexin accumulation through molecular engineering of plant hormones and defense-related marker and elicitor genes have been reviewed

Deciphering the Role of Phytoalexins in Plant-Microorganism Interactions and Human Health

Phytoalexins are low molecular weight antimicrobial compounds that are produced by plants as a response to biotic and abiotic stresses. As such they take part in an intricate defense system which enables plants to control invading microorganisms. In this review we present the key features of this diverse group of molecules, namely their chemical structures, biosynthesis, regulatory mechanisms, biological activities, metabolism and molecular engineering

Rhamnolipids From Pseudomonas aeruginosa Are Elicitors Triggering Brassica napus Protection Against Botrytis cinerea Without Physiological Disorders

International audienc

Morphogenesis of Maize Embryos Requires ZmPRPL35-1 Encoding a Plastid Ribosomal Protein

In emb (embryo specific) mutants of maize (Zea mays), the two fertilization products have opposite fates: Although the endosperm develops normally, the embryo shows more or less severe aberrations in its development, resulting in nonviable seed. We show here that in mutant emb8516, the development of mutant embryos deviates as soon as the transition stage from that of wild-type siblings. The basic events of pattern formation take place because mutant embryos display an apical-basal polarity and differentiate a protoderm. However, morphogenesis is strongly aberrant. Young mutant embryos are characterized by protuberances at their suspensor-like extremity, leading eventually to structures of irregular shape and variable size. The lack of a scutellum or coleoptile attest to the virtual absence of morphogenesis at the embryo proper-like extremity. Molecular cloning of the mutation was achieved based on cosegregation between the mutant phenotype and the insertion of a MuDR element. The Mu insertion is located in gene ZmPRPL35-1, likely coding for protein L35 of the large subunit of plastid ribosomes. The isolation of a second allele g2422 and the complementation of mutant emb8516 with a genomic clone of ZmPRPL35-1 confirm that a lesion in ZmPRPL35-1 causes the emb phenotype. ZmPRPL35-1 is a low-copy gene present at two loci on chromosome arms 6L and 9L. The gene is constitutively expressed in all major tissues of wild-type maize plants. Lack of expression in emb/emb endosperm shows that endosperm development does not require a functional copy of ZmPRPL35-1 and suggests a link between plastids and embryo-specific signaling events