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Maintaining or even increasing crop yields while reducing nitrous oxide (N2O) emissions is necessary to reconcile food security and climate change, while the metric of yield‐scaled N2O emission (i.e., N2O emissions per unit of crop yield) is at present poorly understood. Here we conducted a global meta‐analysis with more than 6000 observations to explore the variation patterns and controlling factors of yield‐scaled N2O emissions for maize, wheat and rice and associated potential mitigation options. Our results showed that the average yield‐scaled N2O emissions across all available data followed the order wheat (322 g N Mg−1, with the 95% confidence interval [CI]: 301–346) > maize (211 g N Mg−1, CI: 198–225) > rice (153 g N Mg−1, CI: 144–163). Yield‐scaled N2O emissions for individual crops were generally higher in tropical or subtropical zones than in temperate zones, and also showed a trend towards lower intensities from low to high latitudes. This global variation was better explained by climatic and edaphic factors than by N fertilizer management, while their combined effect predicted more than 70% of the variance. Furthermore, our analysis showed a significant decrease in yield‐scaled N2O emissions with increasing N use efficiency or in N2O emissions for production systems with cereal yields >10 Mg ha−1 (maize), 6.6 Mg ha−1 (wheat) or 6.8 Mg ha−1 (rice), respectively. This highlights that N use efficiency indicators can be used as valuable proxies for reconciling trade‐offs between crop production and N2O mitigation. For all three major staple crops, reducing N fertilization by up to 30%, optimizing the timing and placement of fertilizer application or using enhanced‐efficiency N fertilizers significantly reduced yield‐scaled N2O emissions at similar or even higher cereal yields. Our data‐driven assessment provides some key guidance for developing effective and targeted mitigation and adaptation strategies for the sustainable intensification of cereal production. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of chloro-aluminum phthalocyanine (ClAlPc) molecules on insulating hexagonal boron nitride (h-BN) monolayers (MLs) grown on Pt(111) surfaces are studied via scanning tunneling microscopy and spectroscopy (STM/STS) along with low energy electron diffraction in ultra-high vacuum conditions. As a reference, the structural properties of the h-BN/Pt(111) surface are studied, where various moiré patterns associated to different orientations of the h-BN lattice with respect to the Pt(111) surface below are characterized, for the first time, at the atomic scale. Room temperature deposition of ClAlPc molecules on h-BN/Pt(111) gives rise to the formation of mainly bilayer molecular structures, where the ClAlPc molecules adopt an alternating Cl-up and Cl-down stacking configuration. Upon annealing, bilayer molecular structures become islands comprising only a single layer of molecules adsorbed in a Cl-up configuration. In the ML regime, the possible influence of the moiré pattern superstructure and the h-BN lattice on the molecular ordering is also studied. Finally, the electronic properties of ClAlPc on h-BN/Pt(111) are investigated through high-resolution STM imaging of the frontier molecular orbitals and differential conductance plots. The results point toward a weak molecule-substrate interaction. [ABSTRACT FROM AUTHOR]

TleD is a SAM (S-adenosyl-L-methionine)-dependent methyltransferase and acts as one of the key enzymes in the teleocidin B biosynthesis pathway. Besides methyl transferring, TleD also rearranges the geranyl and indole moieties of the precursor to form a six-membered ring. Moreover, it does not show homologies with any known terpenoid cyclases. In order to elucidate how such a remarkable reaction could be achieved, we determined the complex crystal structures of TleD and the cofactor analogue S-adenosyl-L-homocysteine with or without the substrate teleocidin A1. A domain-swapped pattern via an additional N-terminal α-helix is observed in TleD hexamers. Structural comparison and alignment shows that this additional N-terminal α-helix is the common feature of SAM methyltransferase-like cyclases TleD and SpnF. The residue Tyr21 anchors the additional N-terminal α-helix to a 'core SAM-MT fold' and is a key residue for catalytic activity. Molecular dynamics simulation results suggest that the dihedral angle C23-C24-C25-C26 of teleocidin A1 is preferred to 60-90± in the TleD and substrate complex structure, which tend to adopt a Re-face stereocenter at C25 position after reaction and is according to in vitro enzyme reaction experiments. Our results also demonstrate that methyl transfer can be a new chemical strategy for carbocation formation in the terpene cyclization, which is the key initial step. [ABSTRACT FROM AUTHOR]