Ethylene modulates wheat response to phosphate deficiency.

Ethylene involves in the response to P deficiency in some model plants, but its relevance to wheat remains limited. Following our recent study demonstrating the role of differentially expressed genes (DEGs) encoding ethylene response factors (ERFs) in response to P starvation in wheat, this study aims to investigate the remodelling of ethylene pathway and the physiological roles of ethylene in wheat under P deficiency using transcriptome analysis and the addition of exogenous ethylene analogue ethephon or ethylene inhibitors. ERFs with at least a two-fold change upon P deficiency were biasedly enriched on chromosome 4 B.

Reducing PHYTOENE SYNTHASE activity fine-tunes the abundance of a cis-carotene-derived signal that regulates the PIF3/HY5 module and plastid biogenesis.

PHYTOENE SYNTHASE (PSY) is a rate-limiting enzyme catalysing the first committed step of carotenoid biosynthesis, and changes in PSY gene expression and/or protein activity alter carotenoid composition and plastid differentiation in plants. Four genetic variants of PSY (psy-4, psy-90, psy-130, and psy-145) were identified using a forward genetics approach that rescued leaf virescence phenotypes and plastid abnormalities displayed by the Arabidopsis CAROTENOID ISOMERASE (CRTISO) mutant ccr2 (carotenoid and chloroplast regulation 2) when grown under a shorter photoperiod. The four non-lethal mutations affected alternative splicing, enzyme-substrate interactions, and PSY:ORANGE multi-enzyme complex binding, constituting the dynamic post-transcriptional fine-tuning of PSY levels and activity without changing localization to the stroma and protothylakoid membranes.

Dynamics of mRNA fate during light stress and recovery: from transcription to stability and translation.

Transcript stability is an important determinant of its abundance and, consequently, translational output. Transcript destabilisation can be rapid and is well suited for modulating the cellular response. However, it is unclear the extent to which RNA stability is altered under changing environmental conditions in plants.

Deregulation of ζ-carotene desaturase in Arabidopsis and tomato exposes a unique carotenoid-derived redundant regulation of floral meristem identity and function.

A level of redundancy and interplay among the transcriptional regulators of floral development safeguards a plant's reproductive success and ensures crop production. In the present study, an additional layer of complexity in the regulation of floral meristem (FM) identity and flower development is elucidated linking carotenoid biosynthesis and metabolism to the regulation of determinate flowering. The accumulation and subsequent cleavage of a diverse array of ζ-carotenes in the chloroplast biogenesis 5 (clb5) mutant of Arabidopsis results in the reprogramming of meristematic gene regulatory networks establishing FM identity mirroring that of the FM identity master regulator, APETALA1 (AP1).

Potential abiotic stress targets for modern genetic manipulation.

Research into crop yield and resilience has underpinned global food security, evident in yields tripling in the past 5 decades. The challenges that global agriculture now faces are not just to feed 10+ billion people within a generation, but to do so under a harsher, more variable, and less predictable climate, and in many cases with less water, more expensive inputs, and declining soil quality. The challenges of climate change are not simply to breed for a "hotter drier climate," but to enable resilience to floods and droughts and frosts and heat waves, possibly even within a single growing season.

Enhancing crop yields through improvements in the efficiency of photosynthesis and respiration.

The rate with which crop yields per hectare increase each year is plateauing at the same time that human population growth and other factors increase food demand. Increasing yield potential ( ) of crops is vital to address these challenges. In this review, we explore a component of that has yet to be optimised - that being improvements in the efficiency with which light energy is converted into biomass ( ) via modifications to CO fixed per unit quantum of light (α), efficiency of respiratory ATP production ( ) and efficiency of ATP use ( ).

Detection and analysis of novel and known plant volatile apocarotenoids.

As the climate becomes increasingly unpredictable due to global warming, plants will encounter a greater challenge to adapt to their hostile environment (e.g., drought, heat, pollution).

Enzymes degraded under high light maintain proteostasis by transcriptional regulation in .

Photoinhibitory high light stress in Arabidopsis leads to increases in markers of protein degradation and transcriptional up-regulation of proteases and proteolytic machinery, but proteostasis is largely maintained. We find significant increases in the in vivo degradation rate for specific molecular chaperones, nitrate reductase, glyceraldehyde-3 phosphate dehydrogenase, and phosphoglycerate kinase and other plastid, mitochondrial, peroxisomal, and cytosolic enzymes involved in redox shuttles. Coupled analysis of protein degradation rates, mRNA levels, and protein abundance reveal that 57% of the nuclear-encoded enzymes with higher degradation rates also had high light–induced transcriptional responses to maintain proteostasis.

Elucidating the role of SWEET13 in phloem loading of the C grass Setaria viridis.

Photosynthetic efficiency and sink demand are tightly correlated with rates of phloem loading, where maintaining low cytosolic sugar concentrations is paramount to prevent the downregulation of photosynthesis. Sugars Will Eventually be Exported Transporters (SWEETs) are thought to have a pivotal role in the apoplastic phloem loading of C grasses. SWEETs have not been well studied in C species, and their investigation is complicated by photosynthesis taking place across two cell types and, therefore, photoassimilate export can occur from either one.

Autophagy mutants show delayed chloroplast development during de-etiolation in carbon limiting conditions.

Autophagy is a conserved catabolic process that plays an essential role under nutrient starvation conditions and influences different developmental processes. We observed that seedlings of autophagy mutants (atg2, atg5, atg7, and atg9) germinated in the dark showed delayed chloroplast development following illumination. The delayed chloroplast development was characterized by a decrease in photosynthetic and chlorophyll biosynthetic proteins, lower chlorophyll content, reduced chloroplast size, and increased levels of proteins involved in lipid biosynthesis.

Addressing Research Bottlenecks to Crop Productivity.

Asymmetry of investment in crop research leads to knowledge gaps and lost opportunities to accelerate genetic gain through identifying new sources and combinations of traits and alleles. On the basis of consultation with scientists from most major seed companies, we identified several research areas with three common features: (i) relatively underrepresented in the literature; (ii) high probability of boosting productivity in a wide range of crops and environments; and (iii) could be researched in 'precompetitive' space, leveraging previous knowledge, and thereby improving models that guide crop breeding and management decisions. Areas identified included research into hormones, recombination, respiration, roots, and source-sink, which, along with new opportunities in phenomics, genomics, and bioinformatics, make it more feasible to explore crop genetic resources and improve breeding strategies.

Deconvoluting apocarotenoid-mediated retrograde signaling networks regulating plastid translation and leaf development.

Signals originating within plastids modulate organelle differentiation by transcriptionally regulating nuclear-encoded genes. These retrograde signals are also integral regulators of plant development, including leaf morphology. The clb5 mutant displays severe leaf morphology defects due to Apocarotenoid Signal 1 (ACS1) accumulation in the developmentally arrested plastid.

Probing functional and optical cross-sections of PSII in leaves during state transitions using fast repetition rate light induced fluorescence transients.

Plants adjust the relative sizes of PSII and PSI antennae in response to the spectral composition of weak light favouring either photosystem by processes known as state transitions (ST), attributed to a discrete antenna migration involving phosphorylation of light-harvesting chlorophyll-protein complexes in PSII. Here for the first time we monitored the extent and dynamics of ST in leaves from estimates of optical absorption cross-section (relative PSII antenna size; aPSII). These estimates were obtained from in situ measurements of functional absorption cross-section (σPSII) and maximum photochemical efficiency of PSII (φPSII); i.

A -carotene derived apocarotenoid regulates etioplast and chloroplast development.

Carotenoids are a core plastid component and yet their regulatory function during plastid biogenesis remains enigmatic. A unique carotenoid biosynthesis mutant, (), that has no prolamellar body (PLB) and normal PROTOCHLOROPHYLLIDE OXIDOREDUCTASE (POR) levels, was used to demonstrate a regulatory function for carotenoids and their derivatives under varied dark-light regimes. A forward genetics approach revealed how an epistatic interaction between a mutant () and blocked the biosynthesis of specific -carotenes and restored PLB formation in etioplasts.

Prospects for Carotenoid Biofortification Targeting Retention and Catabolism.

Due to the ongoing prevalence of vitamin A deficiency (VAD) in developing countries there has been a large effort towards increasing the carotenoid content of staple foods via biofortification. Common strategies used for carotenoid biofortification include altering flux through the biosynthesis pathway to direct synthesis to a specific product, generally β-carotene, or via increasing the expression of genes early in the carotenoid biosynthesis pathway. Recently, carotenoid biofortification strategies are turning towards increasing the retention of carotenoids in plant tissues either via altering sequestration within the cell or via downregulating enzymes known to cause degradation of carotenoids.

Molecular and physiological responses during thermal acclimation of leaf photosynthesis and respiration in rice.

To further our understanding of how sustained changes in temperature affect the carbon economy of rice (Oryza sativa), hydroponically grown plants of the IR64 cultivar were developed at 30°C/25°C (day/night) before being shifted to 25/20°C or 40/35°C. Leaf messenger RNA and protein abundance, sugar and starch concentrations, and gas-exchange and elongation rates were measured on preexisting leaves (PE) already developed at 30/25°C or leaves newly developed (ND) subsequent to temperature transfer. Following a shift in growth temperature, there was a transient adjustment in metabolic gene transcript abundance of PE leaves before homoeostasis was reached within 24 hr, aligning with R (leaf dark respiratory CO release) and A (net CO assimilation) changes.

A GDSL Esterase/Lipase Catalyzes the Esterification of Lutein in Bread Wheat.

Xanthophylls are a class of carotenoids that are important micronutrients for humans. They are often found esterified with fatty acids in fruits, vegetables, and certain grains, including bread wheat (). Esterification promotes the sequestration and accumulation of carotenoids, thereby enhancing stability, particularly in tissues such as in harvested wheat grain.

Excess Light Priming in Genotypes with Altered DNA Methylomes.

Plants must continuously react to the ever-fluctuating nature of their environment. Repeated exposure to stressful conditions can lead to priming, whereby prior encounters heighten a plant's ability to respond to future events. A clear example of priming is provided by the model plant (Arabidopsis), in which photosynthetic and photoprotective responses are enhanced following recurring light stress.

Wheat drought tolerance in the field is predicted by amino acid responses to glasshouse-imposed drought.

Water limits crop productivity, so selecting for a minimal yield gap in drier environments is critical to mitigate against climate change and land-use pressure. We investigated the responses of relative water content (RWC), stomatal conductance, chlorophyll content, and metabolites in flag leaves of commercial wheat (Triticum aestivum L.) cultivars to three drought treatments in the glasshouse and in field environments.

Volatile apocarotenoid discovery and quantification in Arabidopsis thaliana: optimized sensitive analysis via HS-SPME-GC/MS.

Introduction: In the field of carotenoid metabolism researchers' focus has been directed recently toward the discovery and quantification of carotenoid cleavage products (i.e. apocarotenoids, excluding the well-studied carotenoid-derived hormones abscisic acid and strigolactones), due to their emerging roles as putative signaling molecules.

Predicting dark respiration rates of wheat leaves from hyperspectral reflectance.

Greater availability of leaf dark respiration (R ) data could facilitate breeding efforts to raise crop yield and improve global carbon cycle modelling. However, the availability of R data is limited because it is cumbersome, time consuming, or destructive to measure. We report a non-destructive and high-throughput method of estimating R from leaf hyperspectral reflectance data that was derived from leaf R measured by a destructive high-throughput oxygen consumption technique.

Evolution of chloroplast retrograde signaling facilitates green plant adaptation to land.

Chloroplast retrograde signaling networks are vital for chloroplast biogenesis, operation, and signaling, including excess light and drought stress signaling. To date, retrograde signaling has been considered in the context of land plant adaptation, but not regarding the origin and evolution of signaling cascades linking chloroplast function to stomatal regulation. We show that key elements of the chloroplast retrograde signaling process, the nucleotide phosphatase (SAL1) and 3'-phosphoadenosine-5'-phosphate (PAP) metabolism, evolved in streptophyte algae-the algal ancestors of land plants.

A comparison of the EU regulatory approach to directed mutagenesis with that of other jurisdictions, consequences for international trade and potential steps forward.

A special regulatory regime applies to products of recombinant nucleic acid modifications. A ruling from the European Court of Justice has interpreted this regulatory regime in a way that it also applies to emerging mutagenesis techniques. Elsewhere regulatory progress is also ongoing.