Enhanced reservoir evaporation has become an emerging concern regarding water loss, especially when compounded with the ever-increasing water demand. In this study, we evaluated the evaporation rates and losses for 678 major reservoirs (representing nearly 90% of total storage capacity) in the Contiguous United States over historical baseline (1980-2019), near-term (2020-2039), and mid-term (2040-2059) future periods. The evaporation rate was estimated using the Lake Evaporation Model (LEM), an advanced lake evaporation model that addresses both heat storage and fetch effects, driven by multi-ensemble downscaled Coupled Model Intercomparison Projects 6 (CMIP6) projections under the SSP585 emission scenario. The results project that the evaporation loss may increase by 2.5 x 10(7) m(3)/yr through the research period (1980-2059). Among all regions, the Rio Grande is projected to have the largest increasing rate in the near-term and mid-term future, with values of 7.11% of 10.25%, respectively. At the seasonal scale, the most significant increase in the evaporation rate is projected during the fall. The evaporation is projected to increase faster than the streamflow over many of the regions in the southwestern US during the summer/fall, suggesting that the shortage of water will be further exacerbated. The climate models contribute the most to the variance, as compared to the other components related to the projection of evaporation losses (e.g., hydrological model, downscaling method, and historical meteorological data set). These findings demonstrate the need to consider accelerated water loss through open water evaporation in long-term water resources planning across various spatiotemporal scales.

Surface water reservoirs are increasingly being relied upon to meet rising demands in the context of growing population and changing climate. However, the amount of water available in reservoirs (and the corresponding trends) have not been well quantified at the global scale. Here we use satellite observations to estimate the storage variations of 7245 global reservoirs from 1999 to 2018. Total global reservoir storage has increased at a rate of 27.82±0.08 km3/yr, which is mainly attributed to the construction of new dams. However, the normalized reservoir storage (NS)-the ratio of the actual storage to the storage capacity-has declined by 0.82±0.01%. The decline of NS values is especially pronounced in the global south, while the global north mainly exhibits an NS increase. With predicted decreasing runoff and increasing water demand, these observed diminishing storage returns of reservoir construction will likely persist into the future.

The water stress-associated hormone abscisic acid (ABA) acts through a well-defined signal transduction cascade to mediate downstream transcriptional events important for acclimation to stress. Although ABA signaling is known to function in specific tissues to regulate root growth, little is understood regarding the spatial pattern of ABA-mediated transcriptional regulation. Here, we describe the construction and evaluation of an ABSCISIC ACID RESPONSIVE ELEMENT (ABRE)-based synthetic promoter reporter that reveals the transcriptional response of tissues to different levels of exogenous ABA and stresses. Genome-scale yeast one-hybrid screens complemented these approaches and revealed how promoter sequence and architecture affect the recruitment of diverse transcription factors (TFs) to the ABRE. Our analysis also revealed ABA-independent activity of the ABRE-reporter under nonstress conditions, with expression being enriched at the quiescent center and stem cell niche. We show that the WUSCHEL RELATED HOMEOBOX5 and NAC DOMAIN PROTEIN13 TFs regulate QC/SCN expression of the ABRE reporter, which highlights the convergence of developmental and DNA-damage signaling pathways onto this cis-element in the absence of water stress. This work establishes a tool to study the spatial pattern of ABA-mediated transcriptional regulation and a repertoire of TF-ABRE interactions that contribute to the developmental and environmental control of gene expression in roots.

Photosynthesis in leaves generates fixed-carbon resources and essential metabolites that support sink tissues, such as roots. Two of these metabolites, sucrose and auxin, promote growth in root systems, but the explicit connection between photosynthetic activity and control of root architecture has not been explored. Through a mutant screen to identify pathways regulating root system architecture, we identified a mutation in the Arabidopsis thaliana CYCLOPHILIN 38 (CYP38) gene, which causes accumulation of pre-emergent stage lateral roots. CYP38 was previously reported to stabilize photosystem II (PSII) in chloroplasts. CYP38 expression is enriched in shoots, and grafting experiments show that the gene acts non-cell-autonomously to promote lateral root emergence. Growth of wild-type plants under low-light conditions phenocopies the cyp38 lateral root emergence defect, as does the inhibition of PSII-dependent electron transport or Nicotinamide adenine dinucleotide phosphate (NADPH) production. Importantly, these perturbations to photosynthetic activity rapidly suppress lateral root emergence, which is separate from their effects on shoot size. Supplementary exogenous sucrose largely rescued primary root (PR) growth in cyp38, but not lateral root growth. Auxin (indole-3-acetic acid (IAA)) biosynthesis from tryptophan is dependent on reductant generated during photosynthesis. Consistently, we found that wild-type seedlings grown under low light and cyp38 mutants have highly diminished levels of IAA in root tissues. IAA treatment rescued the cyp38 lateral root defect, revealing that photosynthesis promotes lateral root emergence partly through IAA biosynthesis. These data directly confirm the importance of CYP38-dependent photosynthetic activity in supporting root growth, and define the specific contributions of two metabolites in refining root architecture under light-limited conditions.

Stratospheric aerosol injection is one of the most widely studied solar radiation modification methods to reduce some effects of anthropogenic warming. We perform idealized simulations to analyze climate response to different latitudinal and altitudinal distributions of additional stratospheric sulphate aerosols. We analyze climate response to both large volcanic-size aerosols that are representative of sulphate aerosols which form when SO2 is injected into the stratosphere by major volcanic eruptions or by proposed stratospheric sulphate aerosol geoengineering option, and small background-size aerosols which are present in the stratosphere during quiescent periods with no major volcanic eruptions. Our simulations show that under the climate state with doubled atmospheric CO2, for the same total mass, independent of size-distributions, aerosols concentrated at higher latitudes produce less negative effective radiative forcing but larger surface cooling as a result of larger forcing efficacy. For the same latitudinal distribution, small background-size aerosols added at lower altitudes cause larger surface cooling as a result of hygroscopic growth that increases scattering of sunlight. In contrast, large volcanic-size aerosols added at lower altitudes cause smaller surface cooling than at higher altitudes as a result of enhanced stratospheric heating and associated water vapor feedback that enhance absorption of solar and terrestrial radiation. For both background-size and volcanic-size aerosols, asymmetric distributions about the equator induce substantial cross-equatorial energy transport, causing the Intertropical Convergence Zone to move to the warmer hemisphere with less aerosol loading. Our study helps to understand the climate consequences of different spatial patterns and size distributions of stratospheric aerosol perturbation.

In this commentary, we provide additional context for Ocko and Hamburg (2022) related to the climate consequences of replacing fossil fuels with clean hydrogen alternatives. We first provide a tutorial for the derivations of underlying differential equations that describe the radiative forcing of hydrogen emissions, which differ slightly from equations relied on by previous studies. Ocko and Hamburg (2022) defined a metric based on time-integrated radiative forcing from continuous emissions. To complement their analysis, we further present results for temperature and radiative forcing over the next centuries for unit pulse and continuous emissions scenarios. Our results are qualitatively consistent with previous studies, including Ocko and Hamburg (2022). Our results clearly show that for the same quantity of emissions, hydrogen shows a consistently smaller climate impact than methane. As with other short-lived species, the radiative forcing from a continuous emission of hydrogen is proportional to emission rates, whereas the radiative forcing from a continuous emission of carbon dioxide is closely related to cumulative emissions. After a cessation of hydrogen emissions, the Earth cools rapidly, whereas after a cessation of carbon dioxide emissions, the Earth continues to warm somewhat and remains warm for many centuries. Regardless, our results support the conclusion of Ocko and Hamburg (2022) that, if methane were a feedstock for hydrogen production, any possible near-term consequences will depend primarily on methane leakage and secondarily on hydrogen leakage.

Cobalamin (vitamin B12), is a cofactor for crucial metabolic reactions in multiple eukaryotic taxa, including major primary producers such as algae, and yet only prokaryotes can produce it. Many bacteria can colonise the algal phycosphere, forming stable communities that gain preferential access to exudates and in return provide compounds, such as B12. Extended coexistence can then drive gene loss, leading to greater algal-bacterial interdependence. In this study, we investigate how a recently evolved B12-dependent strain of Chlamydomonas reinhardtii, metE7, forms a mutualism with certain bacteria, including the rhizobium Mesorhizobium loti and even a strain of the gut bacterium E. coli engineered to produce cobalamin. Although metE7 was supported by B12 producers, its growth in co-culture was slower than the B12-independent wild-type, suggesting that high bacterial B12 provision may be necessary to favour B12 auxotrophs and their evolution. Moreover, we found that an E. coli strain that releases more B12 makes a better mutualistic partner, and although this trait may be more costly in isolation, greater B12 release provided an advantage in co-cultures. We hypothesise that, given the right conditions, bacteria that release more B12 may be selected for, particularly if they form close interactions with B12-dependent algae.

Genome assembly tools are used to reconstruct genomic sequences from raw sequencing data, which are then used for identifying the organisms present in a metagenomic sample. More recently, machine learning approaches have been applied to a variety of bioinformatics problems, and in this paper, we explore their use for organism identification. We start out by evaluating several commonly used metagenomic assembly tools, including PhyloFlash, MEGAHIT, MetaSPAdes, Kraken2, Mothur, UniCycler, and PathRacer, and compare them against state-of-the art deep learning-based machine learning classification approaches represented by DNABERT and DeLUCS, in the context of two synthetic mock community datasets. Our analysis focuses on determining whether ensembling metagenome assembly tools with machine learning tools has the potential to improve identification performance relative to using the tools individually. We find that this is indeed the case, and analyze the level of effectiveness of potential tool ensembling for organisms with different characteristics (based on factors such as repetitiveness, genome size, and GC content).

Vascular plants appeared similar to 410 million years ago, then diverged into several lineages of which only two survive: the euphyllophytes (ferns and seed plants) and the lycophytes. We report here the genome sequence of the lycophyte Selaginella moellendorffii (Selaginella), the first nonseed vascular plant genome reported. By comparing gene content in evolutionarily diverse taxa, we found that the transition from a gametophyte- to a sporophyte-dominated life cycle required far fewer new genes than the transition from a nonseed vascular to a flowering plant, whereas secondary metabolic genes expanded extensively and in parallel in the lycophyte and angiosperm lineages. Selaginella differs in posttranscriptional gene regulation, including small RNA regulation of repetitive elements, an absence of the trans-acting small interfering RNA pathway, and extensive RNA editing of organellar genes.