https://www.cell.com/trends/plant-science/pdf/S1360-1385(02)02251-3.pdf

GATEWAY vectors for Agrobacterium-mediated plant transformation.

Background
Most genes in Arabidopsis thaliana are members of gene families. How do the members of gene families arise, and how are gene family copy numbers maintained? Some gene families may evolve primarily through tandem duplication and high rates of birth and death in clusters, and others through infrequent polyploidy or large-scale segmental duplications and subsequent losses.

/pdf/the-roles-of-segmental-and-tandem-gene-duplication-in-the-n2p5phw7kl.pdf

The roles of segmental and tandem gene duplication in the evolution of large gene families in Arabidopsis thaliana

1. Introductory remarks 2. Convolvulacaea 2. Scrophulariaceae, Gesneriaceae, Labiatae, etc. 4. Cruciferae, Papaveraceae, Resedaceae, etc. 5. Geraniaceae, Leguminosae, Onagraceae, etc. 6. Solanaceae, Primulaceae, Polygoneae, etc. 7. Summary of the heights and weights of the crossed and self-fertilised plants 8. Difference between crossed and self-fertilised plants in constitutional vigour and in other respects 9. The effects of cross-fertilisation and self-fertilisation on the production of seeds 10. Means of fertilisation 11. The habits of insects in relation to the fertilisation of flowers 12. General results Index.

The Effects of Cross and Self Fertilisation in the Vegetable Kingdom: CONVOLVULACEÆ

Lipid droplets are storage organelles at the centre of lipid and energy homeostasis. They have a unique architecture consisting of a hydrophobic core of neutral lipids, which is enclosed by a phospholipid monolayer that is decorated by a specific set of proteins. Originating from the endoplasmic reticulum, lipid droplets can associate with most other cellular organelles through membrane contact sites. It is becoming apparent that these contacts between lipid droplets and other organelles are highly dynamic and coupled to the cycles of lipid droplet expansion and shrinkage. Importantly, lipid droplet biogenesis and degradation, as well as their interactions with other organelles, are tightly coupled to cellular metabolism and are critical to buffer the levels of toxic lipid species. Thus, lipid droplets facilitate the coordination and communication between different organelles and act as vital hubs of cellular metabolism.

Dynamics and functions of lipid droplets

BRI1/BAK1, a Receptor Kinase Pair Mediating Brassinosteroid Signaling

Growth and development of plants are dependent on the levels and distribution of the phytohormone auxin. Auxin trafficking in plant cells is highly regulated by a variety of plasma membrane auxin carriers. Jaillais et al. now report the discovery of a new intracellular compartment, the SNX1 endosomal compartment, which is involved in the trafficking of one of these auxin carriers. Trafficking of the phytohormone auxin throughout plant cells is highly regulated by a variety of plasma membrane auxin carriers. This study reports the discovery of a new intracellular compartment, the SNX1 endosomal compartment, which is involved in the trafficking of one of these auxin carriers. Polarized cellular distribution of the phytohormone auxin and its carriers is essential for normal plant growth and development. Polar auxin transport 1,2 is maintained by a network of auxin influx (AUX)3 and efflux (PIN)1,2,4,5,6 carriers. Both auxin transport and PIN protein cycling between the plasma membrane and endosomes require the activity of the endosomal GNOM1,2,7,8; however, intracellular routes taken by these carriers remain largely unknown. Here we show that Arabidopsis thaliana SORTING NEXIN 1 (AtSNX1) is involved in the auxin pathway and that PIN2, but not PIN1 or AUX1, is transported through AtSNX1-containing endosomes. We demonstrate that the snx1-null mutant exhibits multiple auxin-related defects and that loss of function of AtSNX1 severely enhances the phenotype of a weak gnom mutant. In root cells, we further show that AtSNX1 localizes to an endosomal compartment distinct from GNOM-containing endosomes, and that PIN2 accumulates in this compartment after treatment with the phosphatidylinositol-3-OH kinase inhibitor wortmannin or after a gravity stimulus. Our data reveal the existence of a novel endosomal compartment involved in PIN2 endocytic sorting and plant development.

AtSNX1 defines an endosome for auxin-carrier trafficking in Arabidopsis

The self-incompatibility response in Brassica allows recognition and rejection of self-pollen by the stigmatic papillae. The transmembrane S-locus receptor kinase (SRK), a member of the receptor-like kinase superfamily in plants, mediates recognition of self-pollen on the female side1, whereas the S-locus cysteine-rich protein (SCR) is the male component of the self-incompatibility response2. SCR is presumably located in the pollen coat, and is thought to be the SRK ligand2,3. Although many receptor-like kinases have been isolated in plants, the mechanisms of signal transduction mediated by these molecules remain largely unknown. Here we show that SRK is phosphorylated in vivo within one hour of self-pollination. We also show that, in vitro, autophosphorylation of SRK is prevented by the stigma thioredoxin THL1 in the absence of a ligand. This inhibition is released in a haplotype-specific manner by the addition of pollen coat proteins. Our data indicate that SRK is inhibited by thioredoxins and activated by pollen coat proteins.

/pdf/the-s-locus-receptor-kinase-is-inhibited-by-thioredoxins-and-13wt0hhvzj.pdf

The S-locus receptor kinase is inhibited by thioredoxins and activated by pollen coat proteins

The Retromer Protein VPS29 Links Cell Polarity and Organ Initiation in Plants

In eukaryotic cells, the endocytic and secretory pathways are key players in several physiological processes These pathways are largely inter-connected in animal and yeast cells through organelles named sorting endosomes Sorting endosomes are multi-vesicular compartments that redirect proteins towards various destinations, such as the lysosomes or vacuoles for degradation, the trans-Golgi network for retrograde transport and the plasma membrane for recycling In contrast, cross-talk between the endocytic and secretory pathways has not been clearly established in plants, especially in terms of cargo protein trafficking Here we show by co-localization analyses that endosomes labelled with the AtSORTING NEXIN1 (AtSNX1) protein overlap with the pre-vacuolar compartment in Arabidopsis root cells In addition, alteration of the routing functions of AtSNX1 endosomes by drug treatments leads to mis-routing of endocytic and secretory cargo proteins Based on these results, we propose that the AtSNX1 endosomal compartment represents a sorting endosome in root cells, and that this specialized organelle is conserved throughout eukaryotes

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2007.03338.x

Evidence for a sorting endosome in Arabidopsis root cells.

Lipid droplets/oil bodies (OBs) are lipid-storage organelles that play a crucial role as an energy resource in a variety of eukaryotic cells. Lipid stores are mobilized in the case of food deprivation or high energy demands--for example, during certain developmental processes in animals and plants. OB degradation is achieved by lipases that hydrolyze triacylglycerols (TAGs) into free fatty acids and glycerol. In the model plant Arabidopsis thaliana, Sugar-Dependent 1 (SDP1) was identified as the major TAG lipase involved in lipid reserve mobilization during seedling establishment. Although the enzymatic activity of SDP1 is associated with the membrane of OBs, its targeting to the OB surface remains uncharacterized. Here we demonstrate that the core retromer, a complex involved in protein trafficking, participates in OB biogenesis, lipid store degradation, and SDP1 localization to OBs. We also report an as-yet-undescribed mechanism for lipase transport in eukaryotic cells, with SDP1 being first localized to the peroxisome membrane at early stages of seedling growth and then possibly moving to the OB surface through peroxisome tubulations. Finally, we show that the timely transfer of SDP1 to the OB membrane requires a functional core retromer. In addition to revealing previously unidentified functions of the retromer complex in plant cells, our work provides unanticipated evidence for the role of peroxisome dynamics in interorganelle communication and protein transport.

https://www.pnas.org/content/pnas/112/13/4158.full.pdf

Thierry Gaude

Papers

AtSNX1 defines an endosome for auxin-carrier trafficking in Arabidopsis

The S-locus receptor kinase is inhibited by thioredoxins and activated by pollen coat proteins

The Retromer Protein VPS29 Links Cell Polarity and Organ Initiation in Plants

Evidence for a sorting endosome in Arabidopsis root cells.

Peroxisome extensions deliver the Arabidopsis SDP1 lipase to oil bodies