A mobile ELF4 delivers circadian temperature information from shoots to roots

Extended Data and Source Data can be found at https://doi.org/10.1038/s41477-020-0634-2Ajuts: the Mas laboratory is funded by the FEDER/Spanish Ministry of Economy and Competitiveness, the Ramon Areces Foundation and the Generalitat de Catalunya (AGAUR). The P.M. laboratory also acknowledges financial support from the CERCA Program, Generalitat de Catalunya and by the Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Program for Centers of Excellence in R&D 2016-2019 (SEV-2015-0533).The circadian clock is synchronized by environmental cues, mostly by light and temperature. Explaining how the plant circadian clock responds to temperature oscillations is crucial to understanding plant responsiveness to the environment. Here, we found a prevalent temperature-dependent function of the Arabidopsis clock component EARLY FLOWERING 4 (ELF4) in the root clock. Although the clocks in roots are able to run in the absence of shoots, micrografting assays and mathematical analyses show that ELF4 moves from shoots to regulate rhythms in roots. ELF4 movement does not convey photoperiodic information, but trafficking is essential for controlling the period of the root clock in a temperature-dependent manner. Low temperatures favour ELF4 mobility, resulting in a slow-paced root clock, whereas high temperatures decrease movement, leading to a faster clock. Hence, the mobile ELF4 delivers temperature information and establishes a shoot-to-root dialogue that sets the pace of the clock in root

Arabidopsis thaliana contains two phosphoenolpyruvate carboxylase kinase genes with different expression patterns

We have already reported the cloning of one phosphoenolpyruvate carboxylase kinase gene from Arabidopsis thaliana (Hartwell et al. 1999, Plant Journal 20, 333–342), hereafter termed PPCK1. A second putative phosphoenolpyruvate carboxylase kinase gene (PPCK2) was identified in the Arabidopsis genome. The corresponding cDNA was amplified from flower tissue by reverse transcriptase (RT)‐polymerase chain reaction (PCR). This cDNA was transcribed and translated in vitro. The translation products possessed high phosphoenolpyruvate carboxylase kinase activity, confirming the identity of the PPCK2 gene. The expression of both phosphoenolpyruvate carboxylase kinase genes was examined by RT‐PCR. PPCK1 is mainly expressed in rosette leaves whereas PPCK2 is expressed in flowers and, at a lower level, in roots and cauline leaves. Light increased the expression of PPCK1 in rosette leaves and that of PPCK2 in flowers. The expression of both genes in an Arabidopsis cell culture was increased by treatment with cycloheximide. The data suggest that the two genes may have different roles in tissue‐specific regulation of phosphoenolpyruvate carboxylase

The International Symposium on Plant Photobiology 2019: a bright and colourful experience

Light is a key resource for plants as it fuels photosynthesis. It also provides essential information about their habitat. Thus, light tracking is of great importance to plants throughout their life cycle. To gain information about their light environment, plants possess light receptors that cover the perception of the complete light spectrum, including light invisible to the human eye (far‐red and ultra‐violet light). The information sensed by these photoreceptors is utilized for optimal growth during day–night cycles and in sub‐optimal light conditions, such as shaded areas and high‐light sun flecks. Plant photobiology research focuses on the perception of light by plants, their developmental adaptations to a changing light environment and the mechanistic and genetic basis of these adaptations. The International Symposium on Plant Photobiology (ISPP) is a biannual meeting where the world's leaders, as well as upcoming talents in the field, gather to share their latest results and discuss future directions. The past edition was held between June 3 and 8 of 2019 in the beautiful PRBB research park building on the seafront of the city of Barcelona (Spain). The ISPP2019 was organized by a gender‐balanced committee formed by two junior (Lot Gommers and Jordi Moreno‐Romero) and two senior researchers (Jamie F. Martínez‐Garcia and Elena Monte).Peer reviewe