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Bread wheat expanded its habitat from a core area of the Fertile Crescent to global environments within ~10,000 years. The genetic mechanisms of this remarkable evolutionary success are not well understood. By whole-genome sequencing of populations from 25 subspecies within the genera Triticum and Aegilops, we identified composite introgression from wild populations contributing to a substantial portion (4-32%) of the bread wheat genome, which increased the genetic diversity of bread wheat and allowed its divergent adaptation. Meanwhile, convergent adaptation to human selection showed 2- to 16-fold enrichment relative to random expectation-a certain set of genes were repeatedly selected in Triticum species despite their drastic differences in ploidy levels and growing zones, indicating the important role of evolutionary constraints in shaping the adaptive landscape of bread wheat. These results showed the genetic necessities of wheat as a global crop and provided new perspectives on transferring adaptive success across species for crop improvement.

Reticulate evolution through the interchanging of genetic components across organisms can impact significantly on the fitness and adaptation of species. Bread wheat (Triticum aestivum subsp. aestivum) is one of the most important crops in the world. Allopolyploid speciation, frequent hybridization, extensive introgression, and occasional horizontal gene transfer (HGT) have been shaping a typical paradigm of reticulate evolution in bread wheat and its wild relatives, which is likely to have a substantial influence on phenotypic traits and environmental adaptability of bread wheat. In this review, we outlined the evolutionary history of bread wheat and its wild relatives with a highlight on the interspecific hybridization events, demonstrating the reticulate relationship between species/subspecies in the genera Triticum and Aegilops. Furthermore, we discussed the genetic mechanisms and evolutionary significance underlying the introgression of bread wheat and its wild relatives. An in-depth understanding of the evolutionary process of Triticum species should be beneficial to future genetic study and breeding of bread wheat.

Bread wheat expanded its habitats from a small core area of the Fertile Crescent to global environments within ∼10,000 years. Genetic mechanisms of this remarkable evolutionary success are not well understood. By whole-genome sequencing of populations from 25 subspecies within generaTriticumandAegilops, we identified composite introgression from these wild populations contributing 13%∼36% of the bread wheat genome, which tremendously increased the genetic diversity of bread wheat and allowed its divergent adaptation. Meanwhile, convergent adaption to human selection showed 2- to 16-fold enrichment relative to random expectation inTriticumspecies despite their drastic differences in ploidy levels and growing zones, indicating the vital importance of adaptive constraints in the success of bread wheat. These results showed the genetic necessities of wheat as a global crop and provided new perspectives on leveraging adaptation success across species for crop improvement.

Urban air pollution generated from straw open burning after the harvest seasons in China has been one of the significant problems interfering with the city's proper functioning. This paper applied contingent valuation in a face to face survey to assess the individual willingness of urban residents in Henan, China to pay for corn straw burning ban to policy makers. Such assessments are important for policy makers to determine the investment and policy instruments for regulating environmental impacts of straw open burning. To investigate the determinants of the stated willingness to pay (WtP) a sample of 1890 urban residents in Henan, China was selected. The study used Tobit model. About 62% of respondents stated that they were willing to pay. The expected WtP was about 76.72 Chinese Yuan (RMB) per person per year for the total respondents and 142.70 RMB per person per year for observations with positive WtP bids. Aggregate value was between 3.41 and 3.90 billion RMB indicating that corn straw burning ban is of considerable economic value to Henan. Results from the study show that the experience of environmental protection, expenditure on protecting health from air pollution, influence of straw burning on respondent's health, life, work, household income, education, job place, and family size were significant variables explaining WtP. The results of the study will be useful for policy makers when making up their mind how much funds should be invested and what kinds of policy instruments could be suitable for banning straw burning. (C) 2018 Published by Elsevier Ltd.

This study investigated smallholder farmers' adoption preferences for cropping patterns of cover crops, duration of adoption, and supplementing technical support to reduce agrochemicals regarding sustainable farm management (SFM). A discrete choice experiment was conducted in the Hexi Corridor (D1) and the west Loess Plateau (D2) in northwest China. The results show that farmers in D1 preferred intercropping and rotating cover crops to the current single cropping system, while farmers in D2 prioritized intercropping over rotation and least preferred planting cover crops in marginal land in the double-cropping system. Farmers in both sites preferred 1 or 3 years of adoption over 5 years. Additionally, farmers in D2 preferred technical assistance to reduce the high proportion of agrochemicals. The results indicate that younger farmers with higher annual household incomes were most likely to opt out in D1. In D2, more agricultural labor inputs and raising livestock had positive effects on the adoption of the package. Moreover, farmers who cultivated cash crops were more reluctant to move away from the current cropping system. This study highlights the uses of cover crop intercropping and rotation combining with technical assistance in different agriculturally intensive cropping systems that may be useful in guiding site-specific policy.

The size of the top three leaves of rice plants is strongly associated with yield; thus, it is important to consider quantitative traits representing leaf size (e.g., length and width) when breeding novel rice varieties. It is challenging to measure such traits on a large scale in the field, and little is known about the genetic factors that determine the size of the top three leaves. In the present study, a population of recombinant inbred lines (RILs) and reciprocal single chromosomal segment substitution lines (SSSLs) derived from the progeny of a japonica Asominori × indica IR24 cross were grown under four diverse environmental conditions. Six morphological traits associated with leaf size were measured, namely length and flag leaf, length and flag, second and third leaves. In the RIL population, 49 QTLs were identified that clustered in 30 genomic region. Twenty-three of these QTLs were confirmed in the SSSL population. A comparison with previously reported genes/QTLs revealed eight novel genomic regions that contained uncharacterized ORFs associated with leaf size. The QTLs identified in this study can be used for marker-assisted breeding and for fine mapping of novel genetic elements controlling leaf size in rice.

The influence of cropping systems on nutrition and food safety is controversial. This study aimed to evaluate the effects of an organic cropping system (OCS) on wheat nutrition and food safety at the molecular level by using a comprehensive research method. Nutrient deviation in samples from an OCS and a conventional cropping system (CCS) were detected, and 58 biomarkers were selected through multivariate statistical analysis and were further qualitatively and quantitatively analyzed. The health risk of heavy metal(loid)s (HMs) for different populations was assessed based on the estimated average daily dose and recommended ingestion reference dose, which indicated that populations ingesting grains from OCSs had higher non-carcinogenic and carcinogenic risks. Additionally, HMs posed greater non-carcinogenic risks to children under five years old and greater carcinogenic risks to adults.This study highlights the need to consider the potential risk from HMs and nutritive ingredient differences in organic food.

Objectives: Intracranial atherosclerotic stenosis (ICAS) is one of the most common causes of stroke worldwide and, in particular, has been implicated as a leading cause of recurrent ischemic stroke. We adapted a rat model of atherosclerosis to study brain intracranial atherosclerosis, and further investigated the effect of omega-3 fatty acids (O3FA) in attenuating development of ICAS. Materials and methods: Adult male Sprague–Dawley rats were divided into control normal-cholesterol or high-cholesterol diet groups with or without O3FA for up to 6 weeks. During the first 2 weeks, NG-nitro- l -arginine methyl ester ( l -NAME, 3 mg/mL) was added to the drinking water of the high-cholesterol groups. The rats received supplementation with O3FA (5 mg/kg/day) by gavages. Blood lipids including low density lipoprotein (LDL), cholesterol (CHO), triglycerides (TG) and high density lipoprotein (HDL) were measured at 3 and 6 weeks. The lumen of middle cerebral artery (MCA) and the thickness of the vessel wall were assessed. Inflammatory molecular markers were assessed by Western blot. Results: A high-cholesterol diet exhibited a significant increase in the classic blood markers (LDL, CHO, and TG) for atherosclerosis, as well as a decrease in HDL. These markers were found to be progressively more severe with time. Lumen stenosis and intimal thickening were increased in MCA. O3FA showed attenuation of blood lipids with an absence of morphological changes. O3FA significantly reduced the inflammatory marker CD68 in MCA and prevented monocyte chemotactic protein (MCP-1) and interferon-γ (IFN-γ) expression in the brain. O3FA similarly decreased inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), and interleukin 6 (IL-6), markers affiliated with monocyte activity in atherosclerosis. Furthermore, O3FA significantly inhibited the expression of vascular cell adhesion molecule-1 (VCAM-1), a marker for endothelial activation. Lastly, O3FA increased ATP-binding cassette transporter A1 (ABCA1) protein expression via silent information regulator 1 (SIRT1) activation, thus increasing cholesterol efflux from macrophages to HDL. Conclusions: Long-term O3FA dietary supplementation prevents the development of intracranial atherosclerosis. This O3FA effect appears to be mediated by its prevention of macrophage infiltration into the vessel wall, therefore reducing inflammation and intimal thickening. While similar effects in humans need to be determined, O3FA dietary supplement shows promising results in the prevention of ICAS.

Exploitation of heterosis has brought significant advance in plant breeding and agricultural production, although its genetic basis is still poorly understood. In this study, a total of 66 chromosome segment substitution (CSS) lines, derived from a cross between japonica rice inbred line Asominori (as the recurrent parent) and indica rice inbred line IR24 (as the donor parent), were used to investigate the genetic basis of heterosis in indica × japonica inter-subspecific rice hybrids. Each CSS line was crossed with the background parent Asominori, and the heterosis of F(1) hybrids was estimated by comparing the F(1) performance with its two parental lines. Field experiments were carried out across six different environments to evaluate yield and yield-related traits in the 66 CSS lines and their 66 corresponding F(1) hybrids. Quantitative trait loci (QTL) analyses were conducted using a likelihood ratio test based on the stepwise regression. Thirty-six QTL were identified with significant effects in CSSL, 21 with significant effects in hybrids and 13 with significant effects in both. On the basis of average dominance degree, of all the 70 QTL affecting yield-related agronomic traits, 28.6% (20) showed an overdominance, 35.7% (25) a partial dominance and 30% (21) an additive effect, indicating that all effects contribute to trait variation in japonica-indica rice hybrids. Effects of these QTL were examined to identify Indica rice chromosome segments of interest for the improvement of japonica inbred lines and hybrids.

Key message This article used seven characters from the 2D image analysis to dissect the genetic architecture underlying rice grain shape in onejaponica × indicapopulation consisting of 215 recombinant inbred lines. Abstract Two-dimensional (2D) digital image analysis is efficient for investigating the rice grain shape characters in large genetic and breeding populations. In this study, we used 2D image analysis to investigate seven characters, i.e., grain length (GL), grain width (GW), length-to-width ratio (LW), grain area (GA), grain circumference (GC), grain diameter (GD), and grain roundness (GR), in one japonica × indica genetic population consisting of 215 recombinant inbred lines. GL and GW can be recorded manually as well, and have been extensively used together with LW (i.e., GL/GW) in genetic studies on grain shape. GC and GA can be hardly measured manually, and have not been used together with GD and GR. Results indicated that the seven characters could be precisely measured by 2D image analysis, genotype by environment interaction was low, and heritability was high. Each character was controlled by a few major stable genes and multiple minor additive genes. A total of 51 QTL were detected for the seven characters across four diverse environments, 22 from GL, GW, and LW, the three traditional characters, and 29 from the other four characters. The 51 QTL were clustered in eighteen marker intervals. Comparing with previous studies and analyzing the stability of identified QTL, we found six non-reported marker intervals, one each on chromosomes 2 and 3, and two each on chromosomes 6 and 8. The newly identified loci and the large-scale phenotyping system would greatly improve our knowledge about the genetic architecture and the future rice breeding on grain shape. Electronic supplementary material The online version of this article (doi:10.1007/s00122-015-2560-7) contains supplementary material, which is available to authorized users.