As a complex wall system in flowering plants, the pollen outer wall mainly contains aliphatic sporopollenin; however, the mechanism for synthesizing these lipidic precursors during pollen development remains less well understood. Here, we report on the function of the rice tapetum-expressing TDR (Tapetum Degeneration Retardation) gene in aliphatic metabolism and its regulatory role during rice pollen development. The observations of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analyses suggested that pollen wall formation was significantly altered in the tdr mutant. The contents of aliphatic compositions of anther were greatly changed in the tdr mutant revealed by GC-MS (gas chromatography-mass spectrometry) testing, particularly less accumulated in fatty acids, primary alcohols, alkanes and alkenes, and an abnormal increase in secondary alcohols with carbon lengths from C29 to C35 in tdr. Microarray data revealed that a group of genes putatively involved in lipid transport and metabolism were significantly altered in the tdr mutant, indicating the critical role of TDR in the formation of the pollen wall. Also, a wide range of genes (236 in total-154 up-regulated and 82 down-regulated) exhibited statistically significant expressional differences between wild-type and tdr. In addition to its function in promoting tapetum PCD, TDR possibly plays crucial regulatory roles in several basic biological processes during rice pollen development.

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Context Urban greenspace provides myriad ecosystem services. To fully understand the ecological services provided by urban greenspace, it is crucial to first accurately quantify the composition and configuration, and change of urban greenspace. Objectives (1) Quantify the dynamics of greenspace in highly urbanized areas. (2) Compare and evaluate the efficacy of medium and high resolution image data on quantifying urban greenspace dynamics. Methods Using two very well-developed urban districts of Beijing, we compare and contrast the changes in urban greenspace from 2005 to 2009 based on two different datasets, the most commonly used Landsat TM data with 30 m resolution, and 2.5 m high spatial resolution imagery.Results We found urban greenspace in the two welldeveloped urban districts of Beijing to be very dynamic, in contrast to findings from previous research that greenspace in inner cities tends to remain largely unchanged. Such dynamics, however, could only be revealed by high spatial resolution imagery because medium resolution data, such as TM data greatly underestimated the percent cover of greenspace. The underestimate neglects smaller elements of greenspace as well as changes in configuration of larger patches, limiting the ability of TM data to detect such changes. Conclusions Our results underscore the importance and necessity of using high spatial resolution data to adequately quantify the distribution of urban greenspace and its change. Results from this study have important implications for urban greenspace management and planning. In addition, the dynamics revealed support emerging conceptions of urban areas as hierarchical patch mosaics.

As the largest pool of terrestrial organic carbon (C), global soils (0-2 m) store more C (∼2,300 Pg) than is found in living plants and the atmosphere combined (Jackson et al., 2017). The controls of soil organic C (SOC) distribution are critical for our understanding of the biosphere, given the importance of SOC for ecosystem processes and its impact on global climate. It has long been known that both climatic and geochemical factors impact the spatial distribution of SOC in mineral soils. However, there is ongoing controversy over their relative importance across broad ecosystem gradients (Rasmussen et al., 2018). For example, climate was found to have a minor or negligible relationship with SOC after accounting for geochemical variation among soils (Doetterl et al., 2015; Fang et al., 2019), strongly challenging established theory that postulated a dominant role for climate over broad spatial scales (Jobbágy & Jackson, 2000; Wynn et al., 2006). Here, we sought to shed light on the discrepancies among these previous studies by evaluating the relative importance of climate, geochemistry, and their interactions for predicting SOC concentrations in mineral soil depth profiles across North America. Soil geochemical composition is a key abiotic control of SOC storage (Lützow et al., 2006) that derives from interactions between parent material and other soil-forming factors, especially climate (Slessarev et al., 2016). Weathering is most intense in humid and warm climates and poorly crystalline (short-rangeordered, SRO) Fe and Al phases and organo-metal complexes may be more persistent under humid and cool conditions (Rasmussen et al., 2007). Reactive minerals and monomeric metals are thought to protect a significant fraction of global SOC stocks from decomposition (Kleber et al., 2015; Kögel-Knabner et al., 2008). SRO Al and Fe minerals have high surface area and reactivity and can effectively adsorb soil organic matter onto their surfaces (Torn et al., 1997). Monomeric Al and Fe species, including their hydroxylated forms, also protect SOC through coprecipitation (Heckman et al., 2013; Wagai & Mayer, 2007). In the circum-neutral and alkaline soils that tend to occur in drier climates, cation bridging (e.g., Ca 2+) between negatively

Aims/hypothesisMost genetic variants identified for type 2 diabetes have been discovered in European populations. We performed genome-wide association studies (GWAS) in a Chinese population with the aim of identifying novel variants for type 2 diabetes in Asians.MethodsWe performed a meta-analysis of three GWAS comprising 684 patients with type 2 diabetes and 955 controls of Southern Han Chinese descent. We followed up the top signals in two independent Southern Han Chinese cohorts (totalling 10,383 cases and 6,974 controls), and performed in silico replication in multiple populations.ResultsWe identified CDKN2A/B and four novel type 2 diabetes association signals with p < 1 × 10−5 from the meta-analysis. Thirteen variants within these four loci were followed up in two independent Chinese cohorts, and rs10229583 at 7q32 was found to be associated with type 2 diabetes in a combined analysis of 11,067 cases and 7,929 controls (pmeta = 2.6 × 10−8; OR [95% CI] 1.18 [1.11, 1.25]). In silico replication revealed consistent associations across multiethnic groups, including five East Asian populations (pmeta = 2.3 × 10−10) and a population of European descent (p = 8.6 × 10−3). The rs10229583 risk variant was associated with elevated fasting plasma glucose, impaired beta cell function in controls, and an earlier age at diagnosis for the cases. The novel variant lies within an islet-selective cluster of open regulatory elements. There was significant heterogeneity of effect between Han Chinese and individuals of European descent, Malaysians and Indians.Conclusions/interpretationOur study identifies rs10229583 near PAX4 as a novel locus for type 2 diabetes in Chinese and other populations and provides new insights into the pathogenesis of type 2 diabetes.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-013-2874-4) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

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Urban megaregions have emerged as a new urbanized form. However, previous studies mostly focused on urban expansion at the city scale, particularly for large cities. Understanding urban expansion at the regional scale including cities having different sizes is important for extending current knowledge of urban growth and its environmental and ecological impacts. Here, we addressed two questions: (1) How do the extent, rate, and morphological model of urban expansion vary at both the regional and city scales? (2) How do factors, such as city size and expansion rate, influence urban expansion models? We focused on the three largest urban megaregions in China, Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD) and Pearl River Delta (PRD). We quantified and compared the spatiotemporal pattern of urban expansion during 2000-2010 at both the regional and city scales based on remote sensing data. We used correlation analysis and linear regressions to address our research questions. We found that (1) the three urban megaregions experienced rapid and massive urban growth, but the spatiotemporal pattern varied greatly. Urban expansion was dominated by edge-expansion in the BTH, edge-expansion and infilling in the YRD, and infilling in the PRD. Cities in the same megaregion tended to have similar expansion morphology; (2) geographical location influenced the model of urban expansion the most, followed by city size and by its expansion rate. Small-sized cities were more likely to develop in a leapfrogging model, while cities with relatively rapid expansion tended to grow in an edge-expansion model.