Elamir Wassim Chehab

• Ph.D
• Faculty Fellow at Rice University

Mammalian small extracellular vesicles (sEVs) can deliver diverse molecules to target cells. However, they are difficult to obtain in large quantities and can activate host immune responses. Plant-derived vesicles may help to overcome these challenges.We optimized isolation methods for two types of plant vesicles, nanovesicles from disrupted leaf a...

Main conclusion Unlike rosette leaves, the mature Arabidopsis rosette core can display full resistance to Botrytis cinerea revealing the importance for spatial and developmental aspects of plant fungal resistance. Abstract Arabidopsis thaliana is a model host to investigate plant defense against fungi. However, many of the reports investigating Ar...

Significance Plants respond to a delicate force signal, such as a light touch, similar to animal neural systems, as demonstrated by thigmotropism, thigmonastic movement, and thigmomorphogenesis. To understand the force-signaling networks, we applied stable isotope labeling in Arabidopsis (SILIA)-based quantitative posttranslational modification pro...

Plants can sense both intracellular and extracellular mechanical forces and can respond through morphological changes. The signaling components responsible for mechanotransduction of the touch response are largely unknown. Here, we performed a high-throughput SILIA (stable isotope labeling in Arabidopsis)-based quantitative phosphoproteomics analys...

Braam and Chehab introduce thigmomorphogenesis - the phenomenon of touch-induced changes in plant growth and development.

We explored the impact of quantum dot (QD) coat characteristics on NP stability, uptake and translocation in Arabidopsis thaliana, and subsequent transfer to primary consumers, Trichoplusia ni (T. ni). Arabidopsis was exposed to CdSe/CdZnS QDs with three different coatings: poly(acrylic acid-ethylene glycol) (PAA-EG), polyethylenimine (PEI) and pol...

Membranes are primary sites of perception of environmental stimuli. Polyunsaturated fatty acids (PUFAs) are major structural constituents of membranes that also function as modulators of a multitude of signal transduction pathways evoked by environmental stimuli. Different stresses induce production of a distinct blend of oxygenated PUFAs, "oxylipi...

The modular design of plants enables individual plant organs to manifest autonomous functions [1] and continue aspects of metabolism, such as respiration, even after separation from the parent plant [2]. Therefore, we hypothesized that harvested vegetables and fruits may retain capacity to perceive and respond to external stimuli. For example, the...

Plants have evolved robust mechanisms to perceive and respond to diverse environmental stimuli. The plant phytohormones jasmonates and salicylates play key roles in activating biotic stress response pathways. Recent findings demonstrate that basal levels of both jasmonates and salicylates in Arabidopsis are under the control of the circadian clock...

Plastid-derived signals are known to coordinate expression of nuclear genes encoding plastid-localized proteins in a process termed retrograde signaling. To date, the identity of retrograde-signaling molecules has remained elusive. Here, we show that methylerythritol cyclodiphosphate (MEcPP), a precursor of isoprenoids produced by the plastidial me...

Plants cannot change location to escape stressful environments. Therefore, plants evolved to respond and acclimate to diverse stimuli, including the seemingly innocuous touch stimulus [1-4]. Although some species, such as Venus flytrap, have fast touch responses, most plants display more gradual touch-induced morphological alterations, called thigm...

Diverse life forms have evolved internal clocks enabling them to monitor time and thereby anticipate the daily environmental changes caused by Earth's rotation. The plant circadian clock regulates expression of about one-third of the Arabidopsis genome, yet the physiological relevance of this regulation is not fully understood. Here we show that th...

Plants constantly interact with a wide range of life-threatening organisms including herbivorous arthropods and pathogenic microbes. The plant fatty acid–derived jasmonates produced in response to biotic stresses are essential to survival. These oxylipins constitute part of the plant’s sophisticated strategy to defend itself. Upon biotic attack, th...

Mechanostimuli can influence plant root system architecture by causing alterations in the root tip growth direction and triggering lateral root initiation. However, how a plant root senses and translates mechanostimulation into appropriate growth and/or developmental responses remains largely unclear. The fast expression induction and transcript tu...

Although plants lack animal-like sensory organs, they still perceive and react to stresses imposed on them by their surrounding environments. Of the various stimuli encountered, mechanical stresses, such as wind, can be detrimental if plants had not evolved mechano-stimulus-induced responses to acclimate to such stimuli. Many of these reactions hav...

Nitric oxide signals diverse responses in animals and plants. Whereas nitric oxide synthesis mechanisms in animals are well understood, how nitric oxide is synthesized and regulated in plants remains controversial. NOA1 is a circularly permuted GTPase that is important for chloroplast function and is implicated in nitric oxide synthesis. However, t...

Jasmonic acid and its derived metabolites (JAs) orchestrate plant defense against insects and fungi. 12-Oxo-phytodienoic acid (OPDA), a JA precursor, has also been implicated in plant defense. We sought to define JAs and OPDA functions through comparative defense susceptibility characteristics of three Arabidopsis (Arabidopsis thaliana) genotypes:...

Fatty acid structure affects cellular activities through changes in membrane lipid composition and the generation of a diversity of bioactive derivatives. Eicosapolyenoic acids are released into plants upon infection by oomycete pathogens, suggesting they may elicit plant defenses. We exploited transgenic Arabidopsis thaliana plants (designated EP)...

Oxylipins, lipid-derived signaling molecules have important functions in plant development, reproduc-tion and responses to external stimuli. Jasmonates (JAs), C 6 -aldehydes, and their corresponding deriv-atives, produced by the two main competing branches of the oxylipin pathway, the allene oxide syn-thase (AOS) and hydroperoxide lyase (HPL) branc...

Organisms are continuously exposed to a myriad of environmental stresses. Central to an organism's survival is the ability to mount a robust transcriptional response to the imposed stress. An emerging mechanism of transcriptional control involves dynamic changes in chromatin structure. Alterations in chromatin structure are brought about by a numbe...

In nature, plants are challenged with hurricane winds, monsoon rains, and herbivory attacks, in addition to many other harsh mechanical perturbations that can threaten plant survival. As a result, over many years of evolution, plants have developed very sensitive mechanisms through which they can perceive and respond to even subtle stimuli, like to...

Background levels of SYD ChIP-qPCR signal in syd-2 plants. ChIP-qPCR analysis of SYD recruitment to the promoters of PDF1.2a (−323 to −151), ERF1 (−1035 to −942), MYC2 (−320 to −222), and VSP2 (−226 to −147). Data are expressed as fold enrichment of SYD relative to IgG. ChIP-qPCR was performed on 12 h wounded Ler and syd-2 plants. Data are means of...

Background: Many inducible plant-defense responses are activated by jasmonates (JAs), C(6)-aldehydes, and their corresponding derivatives, produced by the two main competing branches of the oxylipin pathway, the allene oxide synthase (AOS) and hydroperoxide lyase (HPL) branches, respectively. In addition to competition for substrates, these branch...

Background: Many inducible plant-defense responses are activated by jasmonates (JAs), C6-aldehydes, and their corresponding derivatives, produced by the two main competing branches of the oxylipin pathway, the allene oxide synthase (AOS) and hydroperoxide lyase (HPL) branches, respectively. In addition to competition for substrates, these branch-pa...

McCPK1 (Mesembryanthemum crystallinum calcium-dependent protein kinase 1) mRNA expression is transiently salinity- and dehydrationstress responsive. The enzyme also undergoes dynamic subcellular localization changes in response to these same stresses. Using the yeast-two hybrid system, we have isolated and characterized a M. crystallinum CPK1 Adapt...

Plants have evolved complex signaling pathways to coordinate responses to developmental and environmental information. The oxylipin pathway is one pivotal lipid-based signaling network, composed of several competing branch pathways, that determines the plant's ability to adapt to various stimuli. Activation of the oxylipin pathway induces the de no...

HYDROPEROXIDE LYASE (HPL) genes encode enzymes that catalyze the cleavage of fatty acid hydroperoxides into aldehydes and oxoacids. There are three HPLs in rice (Oryza sativa), designated OsHPL1 through OsHPL3. To explore the possibility of differential functional activities among these genes, we have examined their expression patterns and biochemi...

A salinity and dehydration stress-responsive calcium-dependent protein kinase (CDPK) was isolated from the common ice plant (Mesembryanthemum crystallinum; McCPK1). McCPK1 undergoes myristoylation, but not palmitoylation in vitro. Removal of the N-terminal myristate acceptor site partially reduced McCPK1 plasma membrane (PM) localization as determi...

Calcium-dependent protein kinases (CPK) play important roes as sensor effector molecules in propagating calcium-based signalling pathways . A salinity and drought-stress responsive CPK (CPK1) was isolated from M. crystallinum that exhibits a transiently up regulated expression pattern following drought or salt stress suggesting it links stress-indu...