Screening for Solute Transporters in Plant Photosynthetic Membranes

As compared to chloroplast envelope transporters, the field of thylakoid transporters is largely unexplored. There is evidence for several transport activities in the plant thylakoid membrane, but only a copper P-type ATPase and an ATP/ADP carrier have been so far identified at the gene level in Arabidopsis thaliana. Using in silico analyses, we have predicted the existence of approximately 15 thylakoid transporters, including phosphate transporters and cation channels. For experimental validation, we have used peptide- specific antibodies and functional analyses in heterologous system. These novel data are highly relevant to understand the transport network of the thylakoid membrane and it…

Plant Pigments: Properties, Analysis, Degradation

Publisher Summary This chapter discusses the molecular structures, the general physicochemical properties of plant pigments, and the mechanisms involved in pigment degradation. The invasive and noninvasive methods used for pigment analysis, including the mechanisms involved in pigment degradation, are reviewed. The chapter presents different analytical methods that can be used to identify pigments. All the methods are invasive techniques that are time consuming and often expensive. To reduce sampling and analytical costs, and to speed up the analyses, noninvasive analytical procedures have been developed with the aim to characterize the pigment content of samples, and in the case of food pr…

Cellular and subcellular studies of the arbuscular mycorrhizal symbiosis in M. truncatula: a proteomic survey

TIP family aquaporins play role in chloroplast osmoregulation and photosynthesis

SUMMARYPhotosynthetic oxygen evolution by photosystem II requires water supply into the chloroplast to reach the thylakoid lumen. A rapid water flow is also required into the chloroplast for optimal oxygen evolution and to overcome osmotic stress. The mechanisms governing water transport in chloroplasts are largely unexplored. Previous proteomics indicated the presence of three aquaporins from the tonoplast intrinsic protein (TIP) family, TIP1;1, TIP1;2 and TIP2;1, in chloroplast membranes of Arabidopsis thaliana. Here we revisited their location and studied their role in chloroplasts. Localization experiments indicated that TIP2;1 resides in the thylakoid, whereas TIP1;2 is present in both…

Protochlorophyllide reduction - what is new in 2005?

Because the transformation of protochlorophyllide (Pchlide) to chlorophyllide (Chlide) is an irradiation-dependent process, it is at the heart of the photosynthetic membrane biogenesis, turnover, and adaptation to changes of the environment. I review here the new data published during the year 2004 on Pchlide reduction to Chlide.

Calcium signatures and signaling in cytosol and organelles of tobacco cells induced by plant defense elicitors

Calcium signatures induced by two elicitors of plant defense reactions, namely cryptogein and oligogalacturonides, were monitored at the subcellular level, using apoaequorin-transformed Nicotiana tabacum var Xanthi cells, in which the apoaequorin calcium sensor was targeted either to cytosol, mitochondria or chloroplasts. Our study showed that both elicitors induced specific Ca2+ signatures in each compartment, with the most striking difference relying on duration. Common properties also emerged from the analysis of Ca2+ signatures: both elicitors induced a biphasic cytosolic [Ca2+] elevation together with a single mitochondrial [Ca2+] elevation concomitant with the first cytosolic [Ca2+] p…

Could subcellular proteomics of root plastids teach us more about mycorrhizal symbiosis?

International audience; The arbuscular mycorrhizal (AM) symbiosis is a mutualistic association between soil-borne fungi and the roots of most plant species. Involving the bilateral exchange of nutrients, the symbiosis is connected to drastic changes in plant cell organelle morphology and physiology. Root plastids, in particular, are forming extensive, network-like structures covering the main symbiotic interface, i.e., intracellular, highly branched haustorium-like fungal structures called arbuscules. These plastid networks are highly dynamic and are formed and degraded concomitantly with the formation and degradation of arbuscules. By producing basic metabolic building blocks like fatty ac…

Biologie cellulaire et Physiologie végétale – Phytochrome et Floraison

Food colour additives of natural origin

Abstract Colour is an often overlooked sensory character that certainly influences flavour perception. Pigments colouring food are generally unstable and are modified during processing. To maintain or restore product colour uniformity, colouring agents, considered worldwide as food additives, are intentionally added to food products. The natural food additives market has been growing extensively since the last century due to the potential hazards of artificial food additives and the potential benefits of biologically active compounds. In this chapter, a fairly compressed overview of the most important colours of natural origin as well as information about less common or/and promising colour…

Subcellular proteomics sheds light on root plastid involvement in Medicago truncatula arbuscular mycorrhizal symbiosis

La tolérance au cadmium conférée par la symbiose endomycorhizienne s’accompagne de remaniements protéiques dans les organes aériens

Mycorrhization-induced changes in the root plastid proteome of Medicago truncatula

Arbuscular mycorhizal proteomes: what news at the nearby and distant horizon?

International audience; Proteomics has soon emerged as a powerful tool to point out protein modifications in roots interacting with arbuscular mycorrhiza (AM) fungi. Depending on the developmental mycorrhizal stage and on the available amount of mycorrhizal material, untargeted and/or sub-cellular proteomic approaches were applied to reveal and identify proteins whose accumulation was modified during the AM colonisation of Medicago truncatula roots. For the early stage of symbiosis, the protein patterns obtained from noninoculated roots and roots synchronized for appressorium formation in wild-type (Jemalong J5), penetration-defective (TRV25, dmi3) and autoregulation-defective (TR122, sunn)…

Mycorhizes et jardins verticaux : des potentiels à développer

National audience; Au vu des services écologiques qu'ils peuvent approter, les jardins verticaux sont amenés à se développer. Il en va de même pour les mycorhizes, dont les bénéfices peuvent d'ailleurs profiter à ces nouvelles conceptions végétales.