Heat Stress-Dependent Association of Membrane Trafficking Proteins With mRNPs Is Selective.

The Arabidopsis AAA ATPase SKD1 is essential for ESCRT-dependent endosomal sorting by mediating the disassembly of the ESCRTIII complex in an ATP-dependent manner. In this study, we show that SKD1 localizes to messenger ribonucleoprotein complexes upon heat stress. Consistent with this, the interactome of SKD1 revealed differential interactions under normal and stress conditions and included membrane transport proteins as well as proteins associated with RNA metabolism. Localization studies with selected interactome proteins revealed that not only RNA associated proteins but also several ESCRTIII and membrane trafficking proteins were recruited to messenger ribonucleoprotein granules after heat stress.

Sub-epidermal Expression of ENHANCER OF TRIPTYCHON AND CAPRICE1 and Its Role in Root Hair Formation Upon Pi Starvation.

Root hair patterning is best studied in Arabidopsis thaliana. A pattern of root hair and non-root hair files is governed by a gene-regulatory network of activators and inhibitors. Under phosphate starvation conditions, extra root hairs are formed in non-root hair positions. This raises the question, whether and how this environmental stimulus is mediated by the known root hair gene network. In this study, we provide genetic and molecular data on the role of ETC1 in the phosphate starvation induced ectopic root hair formation. We show that the expression in the epidermis is irregular and reduced and that a new expression domain is induced in the sub-epidermis. By expressing ETC1 in the sub-epidermis, we show that this is sufficient to induce extra root hair formation in N-files. This suggests that the phosphate induced expressional switch from epidermal to epidermal plus sub-epidermal expression of ETC1 is one environmental input to the underlying patterning network.

Analysis of TTG1 function in Arabis alpina.

BACKGROUND: In Arabidopsis thaliana (A. thaliana) the WD40 protein TRANSPARENT TESTA GLABRA1 (TTG1) controls five traits relevant for the adaptation of plants to environmental changes including the production of proanthocyanidin, anthocyanidin, seed coat mucilage, trichomes and root hairs. The analysis of different Brassicaceae species suggests that the function of TTG1 is conserved within the family. RESULTS: In this work, we studied the function of TTG1 in Arabis alpina (A. alpina). A comparison of wild type and two Aattg1 alleles revealed that AaTTG1 is involved in the regulation of all five traits. A detailed analysis of the five traits showed striking phenotypic differences between A. alpina and A. thaliana such that trichome formation occurs also at later stages of leaf development and that root hairs form at non-root hair positions. CONCLUSIONS: The evolutionary conservation of the regulation of the five traits by TTG1 on the one hand and the striking phenotypic differences make A. alpina a very interesting genetic model system to study the evolution of TTG1-dependent gene regulatory networks at a functional level.