Sterol isomerase HYDRA1 interacts with RNA silencing suppressor P1b and restricts potyviral infection.

Plants use RNA silencing as a strong defensive barrier against virus challenges, and viruses counteract this defence by using RNA silencing suppressors (RSSs). With the objective of identifying host factors helping either the plant or the virus in this interaction, we have performed a yeast two-hybrid screen using P1b, the RSS protein of the ipomovirus Cucumber vein yellowing virus (CVYV, family Potyviridae), as a bait. The C-8 sterol isomerase HYDRA1 (HYD1), an enzyme involved in isoprenoid biosynthesis and cell membrane biology, and required for RNA silencing, was isolated in this screen.

A Mutation in the bHLH Domain of the SPCH Transcription Factor Uncovers a BR-Dependent Mechanism for Stomatal Development.

The asymmetric cell divisions necessary for stomatal lineage initiation and progression in Arabidopsis () require the function of the basic helix-loop-helix (bHLH) transcription factor (). Mutants lacking do not produce stomata or lineages. Here, we isolated a new allele carrying a point mutation in the bHLH domain that displayed normal growth, but had an extremely low number of sometimes clustered stomata in the leaves, whereas the hypocotyls did not have any stomata.

Timely expression of the Arabidopsis stoma-fate master regulator MUTE is required for specification of other epidermal cell types.

Epidermal differentiation in Arabidopsis thaliana aerial organs involves stomatal lineage development. Lineages derive from meristemoids, which arise from asymmetric divisions of protodermal cells. Each meristemoid divides repeatedly in an inward spiral before it transits to a guard mother cell (GMC) that produces the stoma, leaving a trail of surrounding stomatal lineage ground cells (SLGCs) that eventually differentiate into endoreplicated pavement cells.

Role of tomato BRANCHED1-like genes in the control of shoot branching.

In angiosperms, shoot branching greatly determines overall plant architecture and affects fundamental aspects of plant life. Branching patterns are determined by genetic pathways conserved widely across angiosperms. In Arabidopsis thaliana (Brassicaceae, Rosidae) BRANCHED1 (BRC1) plays a central role in this process, acting locally to arrest axillary bud growth.

TCP genes: a family snapshot ten years later.

TCP genes encode plant-specific transcription factors with a bHLH motif that allows DNA binding and protein-protein interactions. The TCP gene family has five members in the lycophytes and >20 members in the eudicots. Gene duplication and diversification has generated two clades (class I and II) with slightly different TCP domains.

EARLY IN SHORT DAYS 1 (ESD1) encodes ACTIN-RELATED PROTEIN 6 (AtARP6), a putative component of chromatin remodelling complexes that positively regulates FLC accumulation in Arabidopsis.

We have characterized Arabidopsis esd1 mutations, which cause early flowering independently of photoperiod, moderate increase of hypocotyl length, shortened inflorescence internodes, and altered leaf and flower development. Phenotypic analyses of double mutants with mutations at different loci of the flowering inductive pathways suggest that esd1 abolishes the FLC-mediated late flowering phenotype of plants carrying active alleles of FRI and of mutants of the autonomous pathway. We found that ESD1 is required for the expression of the FLC repressor to levels that inhibit flowering.

Growing up fast: manipulating the generation time of trees.

Domestication and genetic improvement of trees is far behind that of herbaceous plants owing to their long generation times, which result from the existence of a long juvenile phase of reproductive incompetence. During recent years, significant progress has been made towards understanding the molecular basis of flowering transition in model herbaceous species. Some of the genes identified have been shown to efficiently accelerate reproductive development when ectopically expressed in transgenic plants, including trees.