Heritage genetics for adaptation to marginal soils in barley.

Future crops need to be sustainable in the face of climate change. Modern barley varieties have been bred for high productivity and quality; however, they have suffered considerable genetic erosion, losing crucial genetic diversity. This renders modern cultivars vulnerable to climate change and stressful environments.

Gene Replacement in Arabidopsis Reveals Manganese Transport as an Ancient Feature of Human, Plant and Cyanobacterial UPF0016 Proteins.

The protein family 0016 (UPF0016) is conserved through evolution, and the few members characterized share a function in Mn transport. So far, little is known about the history of these proteins in Eukaryotes. In five such proteins, comprising four different subcellular localizations including chloroplasts, have been described, whereas non-photosynthetic Eukaryotes have only one.

Chloroplast Transition Metal Regulation for Efficient Photosynthesis.

Plants require sunlight, water, CO, and essential nutrients to drive photosynthesis and fulfill their life cycle. The photosynthetic apparatus resides in chloroplasts and fundamentally relies on transition metals as catalysts and cofactors. Accordingly, chloroplasts are particularly rich in iron (Fe), manganese (Mn), and copper (Cu).

The Biochemical Properties of Manganese in Plants.

Manganese (Mn) is an essential micronutrient with many functional roles in plant metabolism. Manganese acts as an activator and co-factor of hundreds of metalloenzymes in plants. Because of its ability to readily change oxidation state in biological systems, Mn plays and important role in a broad range of enzyme-catalyzed reactions, including redox reactions, phosphorylation, decarboxylation, and hydrolysis.

Ancient barley landraces adapted to marginal soils demonstrate exceptional tolerance to manganese limitation.

Background And Aims: Micronutrient deficiency in cereals is a problem of global significance, severely reducing grain yield and quality in marginal soils. Ancient landraces represent, through hundreds of years of local adaptation to adverse soil conditions, a unique reservoir of genes and unexplored traits for enhancing yield and abiotic stress tolerance. Here we explored and compared the genetic variation in a population of Northern European barley landraces and modern elite varieties, and their tolerance to manganese (Mn) limitation.

Analysis of Metals in Whole Cells, Thylakoids and Photosynthetic Protein Complexes in sp. PCC6803.

Metals are essential in many biological processes, including oxygenic photosynthesis. Here we described a method to measure the metal pool in whole cells and thylakoids, including the bioactive pool in intact photosynthetic protein complexes in the model oxygenic cyanobacterium PCC6803. In the first part of the protocol, whole cells and thylakoid membranes are carefully prepared, in which the total metal concentrations are measured by inductively coupled plasma triple-quadrupole mass spectrometry (ICP-QQQ-MS).

The Plastid Envelope CHLOROPLAST MANGANESE TRANSPORTER1 Is Essential for Manganese Homeostasis in Arabidopsis.

The transition metal manganese (Mn) is indispensable for photoautotrophic growth since photosystem II (PSII) employs an inorganic MnCaO cluster for water splitting. Here, we show that the Arabidopsis membrane protein CHLOROPLAST MANGANESE TRANSPORTER1 (CMT1) is involved in chloroplast Mn homeostasis. CMT1 is the closest homolog of the previously characterized thylakoid Mn transporter PHOTOSYNTHESIS-AFFECTED MUTANT71 (PAM71).

The Impacts of Phosphorus Deficiency on the Photosynthetic Electron Transport Chain.

Phosphorus (P) is an essential macronutrient, and P deficiency limits plant productivity. Recent work showed that P deficiency affects electron transport to photosystem I (PSI), but the underlying mechanisms are unknown. Here, we present a comprehensive biological model describing how P deficiency disrupts the photosynthetic machinery and the electron transport chain through a series of sequential events in barley ().

The transporter SynPAM71 is located in the plasma membrane and thylakoids, and mediates manganese tolerance in Synechocystis PCC6803.

Manganese (Mn) is an essential constituent of photosystem II (PSII) and therefore indispensable for oxygenic photosynthesis. Very little is known about how Mn is transported, delivered and retained in photosynthetic cells. Recently, the thylakoid-localized transporter PAM71 has been linked to chloroplast Mn homeostasis in Arabidopsis thaliana.

Photosystem II Functionality in Barley Responds Dynamically to Changes in Leaf Manganese Status.

A catalytic manganese (Mn) cluster is required for the oxidation of water in the oxygen-evolving complex (OEC) of photosystem II (PSII) in plants. Despite this essential role of Mn in generating the electrons driving photosynthesis, limited information is available on how Mn deficiency affects PSII functionality. We have here used parameters derived from measurements of fluorescence induction kinetics (OJIP transients), non-photochemical quenching (NPQ) and PSII subunit composition to investigate how latent Mn deficiency changes the photochemistry in two barley genotypes differing in Mn efficiency.

Manganese Deficiency in Plants: The Impact on Photosystem II.

Manganese (Mn) is an essential plant micronutrient with an indispensable function as a catalyst in the oxygen-evolving complex (OEC) of photosystem II (PSII). Even so, Mn deficiency frequently occurs without visual leaf symptoms, thereby masking the distribution and dimension of the problem restricting crop productivity in many places of the world. Hence, timely alleviation of latent Mn deficiency is a challenge in promoting plant growth and quality.

The Evolutionarily Conserved Protein PHOTOSYNTHESIS AFFECTED MUTANT71 Is Required for Efficient Manganese Uptake at the Thylakoid Membrane in Arabidopsis.

In plants, algae, and cyanobacteria, photosystem II (PSII) catalyzes the light-driven oxidation of water. The oxygen-evolving complex of PSII is a Mn4CaO5 cluster embedded in a well-defined protein environment in the thylakoid membrane. However, transport of manganese and calcium into the thylakoid lumen remains poorly understood.

Sensitive Detection of Phosphorus Deficiency in Plants Using Chlorophyll a Fluorescence.

Phosphorus (P) is a finite natural resource and an essential plant macronutrient with major impact on crop productivity and global food security. Here, we demonstrate that time-resolved chlorophyll a fluorescence is a unique tool to monitor bioactive P in plants and can be used to detect latent P deficiency. When plants suffer from P deficiency, the shape of the time-dependent fluorescence transients is altered distinctively, as the so-called I step gradually straightens and eventually disappears.

Metal Binding in Photosystem II Super- and Subcomplexes from Barley Thylakoids.

Metals exert important functions in the chloroplast of plants, where they act as cofactors and catalysts in the photosynthetic electron transport chain. In particular, manganese (Mn) has a key function because of its indispensable role in the water-splitting reaction of photosystem II (PSII). More and better knowledge is required on how the various complexes of PSII are affected in response to, for example, nutritional disorders and other environmental stress conditions.

Manganese deficiency leads to genotype-specific changes in fluorescence induction kinetics and state transitions.

Barley (Hordeum vulgare) genotypes display a marked difference in their ability to tolerate growth at low manganese (Mn) concentrations, a phenomenon designated as differential Mn efficiency. Induction of Mn deficiency in two genotypes differing in Mn efficiency led to a decline in the quantum yield efficiency for both, although faster in the Mn-inefficient genotype. Leaf tissue and thylakoid Mn concentrations were reduced under Mn deficiency, but no difference between genotypes was observed and no visual Mn deficiency symptoms were developed.

Latent manganese deficiency increases transpiration in barley (Hordeum vulgare).

To investigate if latent manganese (Mn) deficiency leads to increased transpiration, barley plants were grown for 10 weeks in hydroponics with daily additions of Mn in the low nM range. The Mn-starved plants did not exhibit visual leaf symptoms of Mn deficiency, but Chl a fluorescence measurements revealed that the quantum yield efficiency of PSII (F(v)/F(m)) was reduced from 0.83 in Mn-sufficient control plants to below 0.