Imaging systemic calcium response and its molecular dissection using virus-induced gene silencing.

Many biotic and abiotic stimuli arrive locally on the plant. For example, attack by an insect or invasion by a fungal pathogen generally starts with a single leaf. However, the responses that are then elicited are often systemic, triggering effects throughout the entire plant body.

Investigating Plasmodesmata Function in Arabidopsis Thaliana Using a Low-Pressure Bombardment System and GFP Movement Assay.

Plasmodesmata are nanopores in the plant cell wall that allow direct cell-to-cell communication. They are key for plant growth, development, and defense. However, studying these pores is challenging due to their small size, with diameters of 30-50 nm and lengths that match cell wall thickness.

Chloroplast-to-nucleus retrograde signalling controls intercellular trafficking via plasmodesmata formation.

The signalling pathways that regulate intercellular trafficking via plasmodesmata (PD) remain largely unknown. Analyses of mutants with defects in intercellular trafficking led to the hypothesis that chloroplasts are important for controlling PD, probably by retrograde signalling to the nucleus to regulate expression of genes that influence PD formation and function, an idea encapsulated in the organelle-nucleus-PD signalling (ONPS) hypothesis. ONPS is supported by findings that point to chloroplast redox state as also modulating PD.

Chloroplasts as mediators of plant biotic interactions over short and long distances.

In nature, plants interact with numerous other organisms. Some interactions benefit both the plant and the other organism(s), while others lead to disease or even death of the plant hosts. The traditional focus of research into plant biotic interactions has been on the negative effects on plants and the strategies plants use to mitigate or prevent these.

The essential chloroplast ribosomal protein uL15c interacts with the chloroplast RNA helicase ISE2 and affects intercellular trafficking through plasmodesmata.

Chloroplasts retain part of their ancestral genomes and the machinery for expression of those genomes. The nucleus-encoded chloroplast RNA helicase INCREASED SIZE EXCLUSION LIMIT2 (ISE2) is required for chloroplast ribosomal RNA processing and chloro-ribosome assembly. To further elucidate ISE2's role in chloroplast translation, two independent approaches were used to identify its potential protein partners.

RNA on the move: The plasmodesmata perspective.

It is now widely accepted that plant RNAs can have effects at sites far away from their sites of synthesis. Cellular mRNA transcripts, endogenous small RNAs and defense-related small RNAs all move from cell to cell via plasmodesmata (PD), and may even move long distances in the phloem. Despite their small size, PD have complicated substructures, and the area of the pore available for RNA trafficking can be remarkably small.

Ethylene Receptors Signal via a Noncanonical Pathway to Regulate Abscisic Acid Responses.

Ethylene is a gaseous plant hormone perceived by a family of receptors in Arabidopsis () including ETHYLENE RESPONSE1 (ETR1) and ETR2. Previously we showed that - loss-of-function plants germinate better and - loss-of-function plants germinate worse than wild-type under NaCl stress and in response to abscisic acid (ABA). In this study, we expanded these results by showing that ETR1 and ETR2 have contrasting roles in the control of germination under a variety of inhibitory conditions for seed germination such as treatment with KCl, CuSO, ZnSO, and ethanol.

The chloroplast RNA helicase ISE2 is required for multiple chloroplast RNA processing steps in Arabidopsis thaliana.

INCREASED SIZE EXCLUSION LIMIT2 (ISE2) is a chloroplast-localized RNA helicase that is indispensable for proper plant development. Chloroplasts in leaves with reduced ISE2 expression have previously been shown to exhibit reduced thylakoid contents and increased stromal volume, indicative of defective development. It has recently been reported that ISE2 is required for the splicing of group II introns from chloroplast transcripts.