Barley Grain Development during Drought Stress: Current Status and Perspectives

Barley (Hordeum vulgare L.) belongs to small grain cereals that cover more than 78% of the daily calorie consumption of humans. With a prediction of 9.7 billion humans in 2050 (FAO stats) and climatic changes, the question of increasing small grain cereal’s production has become an agricultural challenge. Drought exerts a strong environmental pressure, causing large yield losses worldwide. Therefore, understanding the mechanisms responsible for grain development from the fertilization to the mature dry grain is essential to understand how drought can affect this developmental program. In this book chapter, we present the physiological, molecular and hormonal regulation of barley grain development. In a second part, we describe the consequences of drought at different stage of barley development, with a special focus on the reproductive phase. Finally, in the last part, we present the different methods used to decipher new genetic information related to drought-tolerance. All this knowledge contributes to understanding the tolerance mechanisms of barley and to developing breeding strategies aiming to bring about new varieties with sustained yield in harsh conditions

Secretion mechanisms of volatile organic compounds in specialized cells of aromatic plants

The present review focuses on cells secreting volatile odorant compounds. This cell type is found in a wide variety of plants, grouped under the term aromatic plants. Such secreting cells are very diverse in morphology, from highly specialized trichomes to nonspecialized cells, including the secretory epidermal cells of petals and osmophores. In these various types of cell, the biosynthetic pathways of three main groups of volatile organic compounds are recognized: isoprenoids, fatty acid derivatives and aromatic compounds. The precise cellular localization of these pathways has not yet been elucidated in all cases, though many of the enzymes involved have already been cloned. These have been found to be frequently located in plastids but also in endoplasmic reticulum or even cytosol. Two alternative mechanisms of secretion termed granulocrine and eccrine have been postulated to exist. Recent studies support the fact that both mechanisms could exist for different compounds and different plants. This review will discuss also the route by which secreted molecules make their way through the cell wall and cuticle

Modification of Barley Plant Productivity Through Regulation of Cytokinin Content by Reverse-Genetics Approaches

Barley is one of the most important cereals, which is used for breweries, animal and human feeds. Genetic manipulation of plant hormone cytokinins may influence several physiological processes, besides others stress tolerance, root formation and crop yield. In planta, endogenous cytokinin status is finely regulated by the enzyme cytokinin dehydrogenase (EC 1.5.99.12; CKX), that irreversible degrades the side chain of adenine-derived isoprenoid cytokinins. Increasing grain yield by mean of manipulation of endogenous cytokinin content was assayed by the silencing of the HvCKX1 gene. Moreover, to elucidate the putative role of HvCKX1 gene on grain production, knocked-out Hvckx1 mutant plants were generated using the RNA-guided Cas9 system. Homozygote transgenic plants with silenced HvCKX1 gene and azygous knock-out Hvckx1 mutants have been selected and analyzed. Both reduced expression of HvCKX1 gene and CKX activity were measured in different stages of barley grain development. Phenotyping of the transgenic lines revealed reduced root growth, however, plants produced more tillers and grains than azygous wild-type controls and the total yield was increased up to 15 per cent. Although plant productivity was increased, total grain biomass was decreased to 80% of WT grains. RNA-seq analysis of knock-down transgenic lines revealed that several important macronutrient transporters were downregulated in the stage of massive starch accumulation. It suggests that local accumulation of cytokinins negatively affected nutrients flow resulting in reduced grain biomass. Obtained results confirmed the key role of HvCKX1 for regulation of cytokinin content in barley

Tinkering with the C-Function: A Molecular Frame for the Selection of Double Flowers in Cultivated Roses

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Etude de la morphogénèse et de la multiplication de deux hybrides de Protea eximia, "Cardinal" et "Sylvia", en fonction de la période de l'année considérée

* INRA URIH Route des Colles Sophia Antipolis 06410 BIOT Diffusion du document : INRA URIH Route des Colles Sophia Antipolis 06410 BIO

Biosynthèse et sécrétion du parfum chez Rosa x hybrida L.

Roses are the most economically important horticultural species because of their use in fragrance industry and in horticulture. Modern roses are the results of a long selection process lying on the vase life, the pest and disease resistance, the shape and the colour of the flower. Fragrance of roses for the cut flower market was not selected during this process. But nowdays, fragrance is of great interest for the breeders. Perfume of roses is a complex mixture of volatile compounds, mainly monoterpenes. The aim of my work was to characterize the petal of roses as a secretory organ and to isolate and characterize two genes involved in the biosynthetic pathway of monoterpenes. For this purpose, we studied the petal at the ultrastructural level. Both epidermis of the petal are able to synthezize and emit volatile compounds. We identified some structural features putatively involved in the biosynthesis of monoterpenes. A comparative study was made between scented and non-scented varieties but no major differences were observed. Two enzymes involved in the biosynthetic pathway of monoterpenes were studied : RhDXR, involved in IPP biosynthesis and the homodimeric form of RhGPPS, involved in the production of GPP, precursor of monoterpenes. In an in vitro assay, no enzymatic activity was detected for the recombiant RhGPPS. Expression of the corresponding gene was studied by RT-PCR. Its expression is constitutive and not related to biosynthesis of monoterpenes in different rose varieties. RhDXR was characterized as a functional enzyme. The expression of RhDXR was studied by semi-quantitative RT-PCR. By fusions with GFP, we showed that the protein is targeted to the plastids of rose petals. The effect of the overexpression of this gene in transgenic tobaccos is currently under study, with the aim to evaluate the ability of plants to produce more volatiles compounds.La rose présente un intérêt économique très important tant pour son utilisation pour la parfumerie et les cosmétiques que pour son utilisation en horticulture. La rose moderne résulte d'un long processus de sélection au cours duquel les variétés cultivées pour la fleur coupée, notamment, ont perdu leur parfum. Le parfum des roses est un mélange complexe de composés volatils, parmi lesquels les monoterpènes représentent une proportion importante. Aujourd'hui, le parfum est devenu un caractère de choix pour les créateurs de nouvelles variétés. Dans un premier temps, nous nous sommes attaché à caractériser le pétale de rose en tant qu'organe producteur et sécréteur de composés volatils. Nous avons pu montrer que les deux épidermes du pétale produisent et émettent des composés et renferment une enzyme responsable de leur synthèse. Des structures caractéristiques de la synthèse des monoterpènes ont été mises en évidence. Une étude comparative des pétales de roses parfumées et inodores a été réalisée parallèlement. Dans un deuxième temps, deux gènes impliqués dans la biosynthèse des monoterpènes ont été isolés : RhDXR et RhGPPS. L'activité enzymatique de la protéine RhGPPS n'a pas pu être mise en évidence in vitro. L'expression de ce gène est constitutive et non spécifique des roses produisant des monoterpènes. Le gène RhDXR code pour une protéine fonctionnelle. Son expression a été étudiée par RT-PCR semi-quantitative et sa localisation subcellulaire a été précisée par des fusions avec la GFP. Des tabacs transgéniques surexprimant RhDXR sont en cours d'analyse, dans le but d'évaluer la capacité des plantes à augmenter leur production en composés volatils

Biosynthèse et sécrétion du parfum chez Rosa x hybrida L.

La rose présente un intérêt économique très important tant pour son utilisation pour la parfumerie et les cosmétiques que pour son utilisation en horticulture. La rose moderne résulte d'un long processus de sélection au cours duquel les variétés cultivées pour la fleur coupée, notamment, ont perdu leur parfum. Le parfum des roses est un mélange complexe de composés volatils, parmi lesquels les monoterpènes représentent une proportion importante. Aujourd'hui, le parfum est devenu un caractère de choix pour les créateurs de nouvelles variétés. Dans un premier temps, nous nous sommes attaché à caractériser le pétale de rose en tant qu'organe producteur et sécréteur de composés volatils. Nous avons pu montrer que les deux épidermes du pétale produisent et émettent des composés et renferment une enzyme responsable de leur synthèse. Des structures caractéristiques de la synthèse des monoterpènes ont été mises en évidence. Une étude comparative des pétales de roses parfumées et inodores a été réalisée parallèlement. Dans un deuxième temps, deux gènes impliqués dans la biosynthèse des monoterpènes ont été isolés : RhDXR et RhGPPS. L'activité enzymatique de la protéine RhGPPS n'a pas pu être mise en évidence in vitro. L'expression de ce gène est constitutive et non spécifique des roses produisant des monoterpènes. Le gène RhDXR code pour une protéine fonctionnelle. Son expression a été étudiée par RT-PCR semi-quantitative et sa localisation subcellulaire a été précisée par des fusions avec la GFP. Des tabacs transgéniques surexprimant RhDXR sont en cours d'analyse, dans le but d'évaluer la capacité des plantes à augmenter leur production en composés volatilsRoses are the most economically important horticultural species because of their use in fragrance industry and in horticulture. Modern roses are the results of a long selection process lying on the vase life, the pest and disease resistance, the shape and the colour of the flower. Fragrance of roses for the cut flower market was not selected during this process. But nowdays, fragrance is of great interest for the breeders. Perfume of roses is a complex mixture of volatile compounds, mainly monoterpenes. The aim of my work was to characterize the petal of roses as a secretory organ and to isolate and characterize two genes involved in the biosynthetic pathway of monoterpenes. For this purpose, we studied the petal at the ultrastructural level. Both epidermis of the petal are able to synthezize and emit volatile compounds. We identified some structural features putatively involved in the biosynthesis of monoterpenes. A comparative study was made between scented and non-scented varieties but no major differences were observed. Two enzymes involved in the biosynthetic pathway of monoterpenes were studied : RhDXR, involved in IPP biosynthesis and the homodimeric form of RhGPPS, involved in the production of GPP, precursor of monoterpenes. In an in vitro assay, no enzymatic activity was detected for the recombiant RhGPPS. Expression of the corresponding gene was studied by RT-PCR. Its expression is constitutive and not related to biosynthesis of monoterpenes in different rose varieties. RhDXR was characterized as a functional enzyme. The expression of RhDXR was studied by semi-quantitative RT-PCR. By fusions with GFP, we showed that the protein is targeted to the plastids of rose petals. The effect of the overexpression of this gene in transgenic tobaccos is currently under study, with the aim to evaluate the ability of plants to produce more volatiles compounds.ST ETIENNE-BU Sciences (422182103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Additional file 2: of A subtracted cDNA library identifies genes up-regulated during PHOT1-mediated early step of de-etiolation in tomato (Solanum lycopersicum L.)

Nucleic acid sequences of the 168 ESTs found to be putatively up-regulated 30 min after exposure to BL. (DOCX 45 kb

Chemical and Histochemical Analysis of ‘Quatre Saisons Blanc Mousseux’, a Moss Rose of the Rosa × damascena Group

• Background and Aims Moss roses are old garden roses covered with a mossy growth on flower pedicel and calyx. This moss releases a pine-scented oleoresin that is very sticky and odoriferous. Rosa × centifolia ‘muscosa’ was the first moss rose to be obtained by bud-mutation but, interestingly, R. × damascena ‘Quatre Saisons Blanc Mousseux’ was the first repeat-blooming cultivar, thus interesting breeders. In the present study, the anatomy of these sports (i.e. bud-mutations) is characterized and the volatile organic compounds (VOCs) produced by the moss versus the petals are identified. They are compared between the two lines and their respective parents