Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis

Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis–Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity

Middle Bronze Age Settlement in Czeladź Wielka – The Next Step Toward Determining the Habitation Model, Chronology, and Pottery of the Silesian-Greater Poland Tumulus Culture

The article presents the results of research on the habitation model, chronology, and pottery production of the Silesian-Greater Poland Tumulus Culture at Czeladz Wielka settlement (Góra county). The site of the Czeladz Wielka is the first published settlement of the Tumulus culture from the area, providing the first evidence for developing a model of habitation change between the Early and Late Bronze Age. The typochronological analyses allowed positioning the finds in the Middle Bronze Age, while radiocarbon dating placed the site between the late sixteenth and fifteenth century BC. Quantification of technological traits were used to define the general characteristics of Tumulus culture pottery in the region showing the preference for coarse, undecorated, or textile-impressed ceramics. Spatial analyses indicate the presence of a clustered settlement pattern characterized by discard of ceramic material in cultural layer. The findings suggest continuity of certain cultural traits from the preceding Únětice and the influence of contemporary Trzciniec cultural circle

Surveying Rubisco diversity and temperature response to improve crop photosynthetic efficiency.

The threat to global food security of stagnating yields and population growth makes increasing crop productivity a critical goal over the coming decades. One key target for improving crop productivity and yields is increasing the efficiency of photosynthesis. Central to photosynthesis is ribulose-1,5-bisphosphate carboxylase/oxygenase, Rubisco, which is a critical but often rate-limiting component. Here we present full Rubisco catalytic properties measured at three temperatures for 75 plants species representing both crops and undomesticated plants from diverse climates. Some newly characterised Rubiscos were naturally 'better' compared to crop enzymes and have the potential to improve crop photosynthetic efficiency. The temperature response of the various catalytic parameters was largely consistent across the diverse range of species, though absolute values showed significant variation in Rubisco catalysis, even between closely related species. An analysis of residue differences amongst the species characterised identified a number of candidate amino acid substitutions that will aid in advancing engineering of improved Rubisco in crop systems. This study provides new insights on the range of Rubisco catalysis and temperature response present in nature, and provides new information to include in models from leaf to canopy and ecosystem scale

Electron Transfer by Excited Benzoquinone Anions: Slow Rates for Two-Electron Transitions

Electron transfer (ET) rate constants from the lowest excited state of the radical anion of benzoquinone, BQ−•*, were measured in THF solution. Rate constants for bimolecular electron transfer reactions typically reach the diffusion-controlled limit when the free-energy change, ΔG°, reaches −0.3 eV. The rate constants for ET from BQ−•* are one-to-two decades smaller at this energy and do not reach the diffusion-controlled limit until −ΔG° is 1.5−2.0 eV. The rates are so slow probably because a second electron must also undergo a transition to make use of the energy of the excited state. Similarly, ET, from solvated electrons to neutral BQ to form the lowest excited state, is slow, while fast ET is observed at a higher excited state, which can be populated in a transition involving only one electron. A simple picture based on perturbation theory can roughly account for the control of electron transfer by the need for transition of a second electron. The picture also explains how extra driving force (−ΔG°) can restore fast rates of electron transfer

Biochemical characterization of predicted Precambrian RuBisCO

The antiquity and global abundance of the enzyme, RuBisCO, attests to the crucial and longstanding role it has played in the biogeochemical cycles of Earth over billions of years. The counterproductive oxygenase activity of RuBisCO has persisted over billions of years of evolution, despite its competition with the carboxylase activity necessary for carbon fixation, yet hypotheses regarding the selective pressures governing RuBisCO evolution have been limited to speculation. Here we report the resurrection and biochemical characterization of ancestral RuBisCOs, dating back to over one billion years ago (Gyr ago). Our findings provide an ancient point of reference revealing divergent evolutionary paths taken by eukaryotic homologues towards improved specificity for CO2, versus the evolutionary emphasis on increased rates of carboxylation observed in bacterial homologues. Consistent with these distinctions, in vivo analysis reveals the propensity of ancestral RuBisCO to be encapsulated into modern-day carboxysomes, bacterial organelles central to the cyanobacterial CO2 concentrating mechanism

Stability of wheat grain yields over three field seasons in the UK

Ensuring food security in a changing climate is a major contemporary challenge and requires development of climate resilient crops that perform well under variable environments. The hypothesis that yield stability in sub-optimal conditions is linked to yield penalties in optimal conditions was investigated in field-grown wheat in the UK. The phenotypic responses, rate of wheat crop development and final grain yield, to varying sowing date, rainfall, air temperature and radiation patterns were studied for a panel of 61 elite commercial wheat cultivars grown in the UK in 2012, 2013 and 2014. Contrasting climatic patterns, particularly rainfall accumulation and distribution over the season, influenced the relative performance of the cultivars affecting the duration of grain development stage and impacting on productivity. Indices for crop productivity, yield stability and performance under sub-optimal conditions revealed four cultivars with a combination of stable and high relative grain yields over the three seasons: Gladiator, Humber, Mercato and Zebedee. Genetic similarity between cultivars partially explained yield performance in the contrasting seasons. The year of release of the cultivars correlated with grain yield but not with yield stability, supporting the contention that breeding for yield potential does not select for climate resilience and yield stability of crops. Further analysis of the outstanding cultivars may unravel target traits for breeding efforts aimed at increasing wheat yield potential and stability in the changing climate. This article is protected by copyright. All rights reserved

Characterization of chilling-shock responses in four genotypes of Miscanthus reveals the superior tolerance of M. × giganteus compared with M. sinensis and M. sacchariflorus

Abstract Background and Aims The bioenergy grass Miscanthus is native to eastern Asia. As Miscanthus uses C4 photosynthesis, the cooler temperatures experienced in much of northern Europe are expected to limit productivity. Identification of genetic diversity in chilling tolerance will enable breeders to generate more productive varieties for these cooler regions. Characterizing the temporal relationships between photosynthesis, carbohydrate and molecular expression of relevant genes is key to understanding genotypic differences in tolerance or sensitivity. Methods To characterize chilling responses in four Miscanthus genotypes, plants were exposed to a sudden reduction in temperature. The genotypes studied comprised of two M. sinensis, one M. sacchariflorus and one inter-species hybrid, M. × giganteus. Changes in photosynthesis (Asat), carbohydrate composition and the expression of target transcripts were observed following chilling-shock. After 4 d the decline in leaf elongation rate (LER) in the different genotypes was measured. Results Following chilling-shock the greatest decline in Asat was observed in M. sacchariflorus and one M. sinensis genotype. Carbohydrate concentrations increased in all genotypes following chilling but to a lesser extent in M. sacchariflorus. Two stress inducible genes were most highly expressed in the genotypes that experienced the greatest declines in Asat and LER. Miscanthus × giganteus retained the highest Asat and was unique in exhibiting no decline in LER following transfer to 12 °C. Conclusions Miscanthus × giganteus exhibits a superior tolerance to chilling shock than other genotypes of Miscanthus. The absence of sucrose accumulation in M. sacchariflorus during chilling-shock suggests an impairment in enzyme function. A candidate transcription factor, MsCBF3, is most highly expressed in the most sensitive genotypes and may be a suitable molecular marker for predicting chilling sensitivity

Targeted RNA next generation sequencing analysis of cervical smears can predict the presence of hrHPV-induced cervical lesions

Contains fulltext : 251134.pdf (Publisher’s version ) (Open Access

Optimizing the bioenergy water footprint by selecting SRC willow canopy phenotypes: regional scenario simulations

© The Author(s) 2019. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.Background and Aims: Bioenergy is central for the future energy mix to mitigate climate change impacts; however, its intricate link with the water cycle calls for an evaluation of the carbon–water nexus in biomass production. The great challenge is to optimize trade-offs between carbon harvest and water use by choosing cultivars that combine low water use with high productivity. Methods: Regional scenarios were simulated over a range of willow genotype × environment interactions for the major UK soil × climate variations with the process-based model LUCASS. Soil available water capacity (SAWC) ranged from 51 to 251 mm and weather represented the north-west (wet, cool), north-east (dry, cool), south-west (wet, warm) and south-east (dry, warm) of the UK. Scenario simulations were evaluated for small/open narrow-leaf (NL) versus large/closed broad-leaf (BL) willow canopy phenotypes using baseline (1965–89) and warmer recent (1990–2014) weather data. Key Results: The low productivity under baseline climate in the north could be compensated by choosing BL cultivars (e.g. ‘Endurance’). Recent warmer climate increased average productivity by 0.5–2.5 t ha−1, especially in the north. The modern NL cultivar ‘Resolution’ had the smallest and most efficient water use. On marginal soils (SAWC <100 mm), yields remained below an economic threshold of 9 t ha−1 more frequently under baseline than recent climate. In the drought-prone south-east, ‘Endurance’ yielded less than ‘Resolution’, which consumed on average 17 mm year−1 less water. Assuming a planting area of 10 000 ha, in droughty years between 1.3 and 4.5 × 106 m3 of water could be saved, with a small yield penalty, for ‘Resolution’. Conclusions: With an increase in air temperature and occasional water scarcities expected with climate change, high-yielding NL cultivars should be the preferred choice for sustainable use of marginal lands and reduced competition with agricultural food crops.Peer reviewedFinal Published versio