Simon R Law

The Commonwealth Scientific and Industrial Research Organisation | CSIRO · Agriculture and Food

Germination represents a rapid transition from dormancy to a high level of metabolic activity. In-depth transcriptomic profiling at 10 time points in Arabidopsis (Arabidopsis thaliana), including fresh seed, ripened seed, during stratification, germination, and postgermination per se, revealed specific temporal expression patterns that to our knowl...

Mitochondria play a crucial role in germination and early seedling growth in Arabidopsis (Arabidopsis thaliana). Morphological observations of mitochondria revealed that mitochondrial numbers, typical size, and oval morphology were evident after 12 h of imbibition in continuous light (following 48 h of stratification). The transition from a dormant...

In plants, an individually darkened leaf (IDL) initiates senescence much more rapidly than a leaf from a whole darkened plant (DP). Combining transcriptomic and metabolomic approaches in Arabidopsis thaliana, we present an overview of the metabolic strategies that are employed in response to different darkening treatments. Under DP conditions, the...

Carbon storage and cycling in boreal forests-the largest terrestrial carbon store-is moderated by complex interactions between trees and soil microorganisms. However, existing methods limit our ability to predict how changes in environmental conditions will alter these associations and the essential ecosystem services they provide. To address this,...

Leaf senescence can be induced by stress or aging, sometimes in a synergistic manner. It is generally acknowledged that the ability to withstand senescence-inducing conditions can provide plants with stress resilience. Although the signaling and transcriptional networks responsible for a delayed senescence phenotype, often referred to as a function...

At first glance, the term Urban Forest may appear a contradiction. However, the purposeful incorporation and management of public green areas into urban spaces has been practiced for over 300 years, as cities transformed from compact medieval fortifications into sprawling municipalities driven by the shifting paradigms of the Age of Enlightenment a...

Those who live in glass houses should not throw stones. This well‐worn proverb tells of the peril of casting criticism from a position of vulnerability.However, there are a number of examples in the natural world where the incorporation of glass (silica or silicon dioxide to be more precise) into the structural make‐up of an organism can greatly in...

Iron (Fe) is an essential element for the development and physiology of plants owing to its presence in numerous proteins involved in central biological processes. Here, we established an exhaustive, manually curated inventory of genes encoding Fe-containing proteins in Arabidopsis thaliana, and summarised their subcellular localisation, spatiotemp...

It is difficult to separate the capacity for memory from the act of thinking. Indeed, memories are held as so fundamental an act of cognition that the concept of an organism without a brain (let alone a nervous system) storing and acting upon memories is profoundly outlandish. Despite this, research emerging from the field of plant science is conti...

The emergence of yellow and red hued foliage in plants, which we commonly associate with vegetal decline or a fore-shadowing of winter, signals the progression of a process know n as leaf senescence. It is characterised by a series of carefully orchestrated degradation events, which liberate nutrients from senescing tissues and redistribute them to...

Gene co-expression networks (GCNs) can be prepared using a variety of mathematical approaches based on data sampled across diverse developmental processes, tissue types, pathologies, mutant backgrounds, and stress conditions. These networks are used to identify genes with similar expression dynamics but are prone to introducing false-positive and f...

Efforts to decipher the processes underpinning biological systems now have a plethora of approaches from which to choose. Transcriptomics and proteomics provide a global snapshot of the abundance of gene products in a sample, from which researchers can learn a great deal about the inner machinations of a cell. However, when attempting to piece toge...

Putrescine is a member of a group of aliphatic compounds, known as polyamines, which are derived from the breakdown of amino acids in living (and dead) cells. Along with the grimly named cadaverine, putrescine was discovered in 1885 by the German physician Ludwig Brieger, who identified these polyamines as the primary constituent of the foul odours...

Drought is an increasingly common climatic event that can devastate ecosystems, as well as surrounding agricultural and forestry industries. Few places face this challenge more than Australia, where millennia of droughts linked to geography and climatic drivers, such as El Niño, have shaped the flora and fauna into forms predicated on resilience an...

Gene Co-expression Networks (GCNs) are obtained by a variety of mathematical of models commonly derived on data sampled from diverse developmental processes, tissue types, pathologies, mutant backgrounds, and stress conditions. These networks aim to identify genes with similar expression dynamics, but are prone to introduce false-positive and -nega...

Beneath the gardens, farmlands and forest floors that surround us, a hidden world blooms in careful cooperation and intense competition. The mutualistic symbiosis of the thread-like hyphae of fungi and plant roots (collectively termed mycorrhizae from the Greek m ´ yk ¯ es-meaning 'fungus', and rhiza-for 'root') is present in the vast majority of p...

Glutathione transferases (GSTs) belong to a ubiquitous multigenic family of enzymes involved in diverse biological processes including xenobiotic detoxification and secondary metabolism. A canonical GST is formed by two domains, the N-terminal one adopting a thioredoxin (TRX) fold and the C-terminal one an all-helical structure. The most recent gen...

It is difficult to overstate the role of wood in the story of humanity. In times that predate recorded history it provided shelter from the elements, light and warmth when burned, and a supple material with which early humans could craft their first tools. Today, it is still one of our chief building materials and an emerging industry is extending...

Soils represent the largest and most stable carbon pools on Earth, exceeding even the carbon aggregate found in the atmosphere and global phytomass. However, our understanding of how CO₂ travels from the soil to the atmosphere, and the role of plants in this journey, is not fully understood. An article in this issue of Physiologia Plantarum (Shimon...

I made the illustration for this Spotlight article published by Physiologia Plantarum, written by Simon Law.

Barley (Hordeum vulgare), a vital crop to the food and beverage industry, is highly vulnerable to unstable conditions on the climatic horizon. An article in this special issue of Physiologia Plantarum by Mahalingam and Bregitzer (2019) describes the impact that individual and combined stresses linked to climate change could have on the agronomic so...

I contributed with the illustrations for this Spotlight article published by Physiologia Plantarum and written by Simon R. Law

In plant cells, mitochondria are major providers of energy and building blocks for growth and development as well as abiotic and biotic stress responses. They are encircled by two lipid membranes containing proteins that control mitochondrial function through the import of macromolecules and metabolites. Characterization of a novel beta-barrel prot...

Previous studies have identified a range of transcription factors that modulate retrograde regulation of mitochondrial and chloroplast functions in Arabidopsis thaliana. However, the relative importance of these regulators and whether they act downstream of separate or overlapping signalling cascades is still unclear. Here we demonstrate that multi...

At12Cys-1 (At5g64400) and At12Cys-2 (At5g09570) are two closely related isogenes that encode small, twin cysteine proteins, typically located in mitochondria. At12Cys-2 transcript is induced in a variety of mutants that encode mitochondrial proteins, but an increase in At12Cys protein is only detected in mutants with reduced complex I abundance. In...

Mitochondria have emerged as an important organelle for sensing and coping with stress, in addition to being the sites of important metabolic pathways. Here, responses to moderate light and drought stress were examined in different Arabidopsis thaliana mutant plants lacking a functional alternative oxidase (aox1a), those with reduced cytochrome ele...

In Arabidopsis thaliana, small gene families encode multiple isoforms for many of the components of the mitochondrial protein import apparatus. There are three isoforms of the translocase of the inner membrane 17 (Tim17). Transcriptome analysis indicates that AtTim17-1 is only detectable in dry seed. In this study, two independent T-DNA insertional...

One of the most stress-responsive genes encoding a mitochondrial protein in Arabidopsis (At3g50930) has been annotated as AtBCS1 (cytochrome bc1 synthase 1), but was previously functionally uncharacterised. Here, we show that the protein encoded by At3g50930 is present as a homo-multimeric protein complex on the outer mitochondrial membrane and lac...

The perception and integration of stress stimuli with that of mitochondrion function are important during periods of perturbed cellular homeostasis. In a continuous effort to delineate these mitochondrial/stress interacting networks, forward genetic screens, utilizing the mitochondrial stress response marker, AOX1a (Alternative oxidase1a), provide...

Mitochondria occupy a central role in the eukaryotic cell. In addition to being major sources of cellular energy, mitochondria are also involved in a diverse range of functions including signalling, the synthesis of many essential organic compounds and a role in programmed cell death. The active proliferation and differentiation of mitochondria is...

Mitochondrial biogenesis and function in plants requires the expression of over one thousand nuclear genes encoding mitochondrial proteins (NGEMPs). The expression of these genes is regulated by tissue-specific, developmental, internal and external stimuli that result in a dynamic organelle involved in both metabolic and a variety of signalling pro...

Plants require daily coordinated regulation of energy metabolism for optimal growth and survival and therefore need to integrate cellular responses with both mitochondrial and plastid retrograde signaling. Using a forward genetic screen to characterize regulators of alternative oxidase1a (rao) mutants, we identified RAO2/Arabidopsis NAC domain-cont...

Upon disturbance of their function by stress, mitochondria can signal to the nucleus to steer the expression of responsive genes. This mitochondria-to-nucleus communication is often referred to as mitochondrial retrograde regulation (MRR). Although reactive oxygen species and calcium are likely candidate signaling molecules for MRR, the protein sig...

Background / Purpose: A number of proteins have been found to be located in more than one organelle, termed “dual targeting”. We aimed to gain further insight into when the dual targeting of proteins originated, and whether it is conserved. Main conclusion: Dual targeting arose earlier in plant evolution and is well conserved. Loss and gain of...

Type II NAD(PH) dehydrogenases are located on the inner mitochondrial membrane of plants, fungi, protists and some primitive animals. However, recent observations have been made which identify several Arabidopsis type II dehydrogenases as dual targeted proteins. Targeting either mitochondria and peroxisomes or mitochondria and chloroplasts. Members...

The expression of a variety of nuclear genes encoding mitochondrial proteins is known to adapt to changes in environmental conditions and retrograde signalling. The presence of putative WRKY transcription factor binding sites (W-boxes) in the promoters of many of these genes prompted a screen of 72 annotated WRKY factors in the Arabidopsis thaliana...

The dual targeting ability of a variety of proteins from Physcomitrella patens, Oryza sativa and Arabidopsis thaliana were tested to determine when dual targeting arose and to what extent it is conserved in land plants. Overall the targeting ability of over 80 different proteins from rice and Physcomitrella representing 42 dual-targeted proteins in...

Plants must deal effectively with unfavorable growth conditions that necessitate a coordinated response to integrate cellular signals with mitochondrial retrograde signals. A genetic screen was carried out to identify regulators of alternative oxidase (rao mutants), using AOX1a expression as a model system to study retrograde signaling in plants. T...

The Arabidopsis thaliana genome contains two genes with homology to the mitochondrial protein LETM1 (leucine zipper-EF-hand-containing transmembrane protein). Inactivation of both genes, Atletm1 and Atletm2, together is lethal. Plants that are hemizygous for AtLETM2 and homozygous for Atletm1 (letm1(−/−) LETM2(+/−)) displayed a mild retarded growth...

To date, Arabidopsis purple acid phosphatase 2 (AtPAP2) is the only known plant protein that is dual-targeted to chloroplasts and mitochondria by a C-terminal targeting signal. Using in vitro organelle import and green fluorescence protein (GFP) localization assays, we showed that AtPAP2 is located on, but not imported across the outer membrane (OM...

To date, Arabidopsis purple acid phosphatase 2 (AtPAP2) is the only known plant protein that is dual-targeted to chloroplasts and mitochondria by a C-terminal targeting signal. Using in vitro organelle import and green fluorescence protein (GFP) localization assays, we showed that AtPAP2 is located on, but not imported across the outer membrane (OM...