Increasing homogeneity in global food supplies and the implications for food security

The narrowing of diversity in crop species contributing to the world’s food supplies has been considered a potential threat to food security. However, changes in this diversity have not been quantified globally. We assess trends over the past 50 y in the richness, abundance, and composition of crop species in national food supplies worldwide. Over this period, national per capita food supplies expanded in total quantities of food calories, protein, fat, and weight, with increased proportions of those quantities sourcing from energy-dense foods. At the same time the number of measured crop commodities contributing to national food supplies increased, the relative contribution of these commodities within these supplies became more even, and the dominance of the most significant commodities decreased. As a consequence, national food supplies worldwide became more similar in composition, correlated particularly with an increased supply of a number of globally important cereal and oil crops, and a decline of other cereal, oil, and starchy root species. The increase in homogeneity worldwide portends the establishment of a global standard food supply, which is relatively species-rich in regard to measured crops at the national level, but species-poor globally. These changes in food supplies heighten interdependence among countries in regard to availability and access to these food sources and the genetic resources supporting their production, and give further urgency to nutrition development priorities aimed at bolstering food security.A shared axiom of ecology and nutrition is that, within certain ranges, diversity enhances the health and function of complex biological systems. Species diversity has been shown to stimulate productivity, stability, ecosystem services, and resilience in natural (1–5) and in agricultural ecosystems (6–13). Likewise, variation in food species contributing to diet has been associated with nutritional adequacy (14–17) and food security (18).The development of sedentary agricultural societies and further rise of modern agriculture is generally considered to have led to a decline in the total number of plant species upon which humans depend for food (19, 20), particularly the wild, semidomesticated, and cultivated vegetables and fruits, spices, and other food plants that supplemented staple crops with the provision of micronutrients and that bolstered food security historically during crop failures (21). Harlan (20) warned that

most of the food for mankind comes from a small number of crops and the total number is decreasing steadily. In the United States in the past 40 years, many vegetables and fruits have disappeared from the diet, and the trend is going on all over the world. More and more people will be fed by fewer and fewer crops.

More recent analyses of dietary transition in developing countries in association with globalization have noted increases in the diversity of plants contributing to diets locally, along with a Westernization transition in preference of energy-dense foods (i.e., animal products, plant oils, and sugars) over cereals, pulses, and vegetables, and of particular major crop plants within these food categories over traditional crops (22, 23). The impact of such changes on overall crop diversity worldwide has not been comprehensively documented, although recent changes in varietal and allelic level diversity of some crops have been investigated (24–26). Given the potential food security implications of narrowing of the diversity of crop species both in production systems and in food supplies, an assessment of the global state of crop plant species diversity is warranted.Here we examine changes in the diversity of the portfolio of crop species upon which humans primarily depend for food security in regard to calories, protein, fat, and food weight. Using national per capita food supply data published by the Food and Agriculture Organization (FAO) of the United Nations, we analyzed trends in the richness, abundance, and composition of measured crop commodities in the food supplies of 152 countries comprising 98% of the world’s population from 1961 to 2009.     

Spontaneous spatiotemporal waves of gene expression from biological clocks in the leaf

The circadian clocks that drive daily rhythms in animals are tightly coupled among the cells of some tissues. The coupling profoundly affects cellular rhythmicity and is central to contemporary understanding of circadian physiology and behavior. In contrast, studies of the clock in plant cells have largely ignored intercellular coupling, which is reported to be very weak or absent. We used luciferase reporter gene imaging to monitor circadian rhythms in leaves of Arabidopsis thaliana plants, achieving resolution close to the cellular level. Leaves grown without environmental cycles for up to 3 wk reproducibly showed spatiotemporal waves of gene expression consistent with intercellular coupling, using several reporter genes. Within individual leaves, different regions differed in phase by up to 17 h. A broad range of patterns was observed among leaves, rather than a common spatial distribution of circadian properties. Leaves exposed to light-dark cycles always had fully synchronized rhythms, which could desynchronize rapidly. After 4 d in constant light, some leaves were as desynchronized as leaves grown without any rhythmic input. Applying light-dark cycles to such a leaf resulted in full synchronization within 2-4 d. Thus, the rhythms of all cells were coupled to external light-dark cycles far more strongly than the cellular clocks were coupled to each other. Spontaneous desynchronization under constant conditions was limited, consistent with weak intercellular coupling among heterogeneous clocks. Both the weakness of coupling and the heterogeneity among cells are relevant to interpret molecular studies and to understand the physiological functions of the plant circadian clock.     

Community-wide convergent evolution in insect adaptation to toxic cardenolides by substitutions in the Na,K-ATPase

The extent of convergent molecular evolution is largely unknown, yet is critical to understanding the genetics of adaptation. Target site insensitivity to cardenolides is a prime candidate for studying molecular convergence because herbivores in six orders of insects have specialized on these plant poisons, which gain their toxicity by blocking an essential transmembrane carrier, the sodium pump (Na,K-ATPase). We investigated gene sequences of the Na,K-ATPase α-subunit in 18 insects feeding on cardenolide-containing plants (spanning 15 genera and four orders) to screen for amino acid substitutions that might lower sensitivity to cardenolides. The replacement N122H that was previously shown to confer resistance in the monarch butterfly (Danaus plexippus) and Chrysochus leaf beetles was found in four additional species, Oncopeltus fasciatus and Lygaeus kalmii (Heteroptera, Lygaeidae), Labidomera clivicollis (Coleoptera, Chrysomelidae), and Liriomyza asclepiadis (Diptera, Agromyzidae). Thus, across 300 Myr of insect divergence, specialization on cardenolide-containing plants resulted in molecular convergence for an adaptation likely involved in coevolution. Our screen revealed a number of other substitutions connected to cardenolide binding in mammals. We confirmed that some of the particular substitutions provide resistance to cardenolides by introducing five distinct constructs of the Drosophila melanogaster gene into susceptible eucaryotic cells under an ouabain selection regime. These functional assays demonstrate that combined substitutions of Q(111) and N(122) are synergistic, with greater than twofold higher resistance than either substitution alone and >12-fold resistance over the wild type. Thus, even across deep phylogenetic branches, evolutionary degrees of freedom seem to be limited by physiological constraints, such that the same molecular substitutions confer adaptation.     

Permian vegetational Pompeii from Inner Mongolia and its implications for landscape paleoecology and paleobiogeography of Cathaysia

Plant communities of the geologic past can be reconstructed with high fidelity only if they were preserved in place in an instant in time. Here we report such a flora from an early Permian (ca. 298 Ma) ash-fall tuff in Inner Mongolia, a time interval and area where such information is filling a large gap of knowledge. About 1,000 m(2) of forest growing on peat could be reconstructed based on the actual location of individual plants. Tree ferns formed a lower canopy and either Cordaites, a coniferophyte, or Sigillaria, a lycopsid, were present as taller trees. Noeggerathiales, an enigmatic and extinct spore-bearing plant group of small trees, is represented by three species that have been found as nearly complete specimens and are presented in reconstructions in their plant community. Landscape heterogenity is apparent, including one site where Noeggerathiales are dominant. This peat-forming flora is also taxonomically distinct from those growing on clastic soils in the same area and during the same time interval. This Permian flora demonstrates both similarities and differences to floras of the same age in Europe and North America and confirms the distinct character of the Cathaysian floral realm. Therefore, this flora will serve as a baseline for the study of other fossil floras in East Asia and the early Permian globally that will be needed for a better understanding of paleoclimate evolution through time.     

共生真菌对植物抗旱性的影响及机制研究进展

共生真菌分布广泛,与植物形成共生体。研究表明,某些共生真菌可以增强植物对生物胁迫和非生物胁迫,包括干旱、高温、矿物质失调和高盐的耐受性,从而使被内生真菌感染的植株比未感染植株对有限的资源更具竞争力而且生长得更好。植物共生真菌可以通过多样化途径来增强植物体的抗性机能,其提高抗旱性的机制主要表现在营养物质的吸收、植物的保护系统、激素调节、水解酶、水分代谢、相关基因表达、植物防御信号途径等方面。总结共生真菌提高植物耐旱性的机制研究进展,以使读者能全面、及时地了解这一领域的研究动态。     

基于污水流行病学的广州和珠海4种心血管药物消费量的估算研究

目的了解广州和珠海城市污水处理厂进水中的4种心血管药物浓度,并对其消费量进行估算。方法分别于2017年5月9至22日(春季)和9月27日至10月12日(秋季)采集广州1座污水厂进水水样,2017年1月23日至2月5日(冬季)采集珠海1座污水厂进水水样,采用固相萃取-液相色谱-串联质谱法检测美托洛尔(MET)、阿替洛尔(ATE)、吉非罗齐(GFB)、苯扎贝特(BZB)的浓度,应用污水流行病学方法估算4种心血管药物在广州和珠海的消费量。结果 4种心血管药物均有检出,浓度范围在未检出~889.73 ng/L之间,检出率在14.29%~100%之间。在4种心血管药物中,以MET和BZB浓度较高,其最高浓度分别达733.71和889.73 ng/L。与珠海市比较,广州市污水厂进水中MET、BZB、GFB的浓度较高,差异均有统计学意义(P<0.01);而ATE的浓度无明显差异。不论在广州市还是珠海市,MET的消费量均远高于BZB、GFB、ATE,4种药物在两城市的消费模式均为MET>BZB>GFB>ATE。与珠海市比较,广州市MET、BZB、GFB消费量较高,差异均有统计学意义(P<0.01);而ATE的消费量无明显差异。不论是春季还是秋季,MET均为消费量最高的药物,ATE均为消费量最低的药物。与春季比较,秋季ATE的消费量较低,差异有统计学意义(P<0.01);而MET、BZB、GFB无明显改变。结论不同地区的心血管药物消费存在较大差异,广州市的MET、BZB、GFB、ATE消费量高于珠海。     

An in vitro study of the effect of some dietary components on calculus formation: regulation of calcium phosphate precipitation

OBJECTIVE: We studied the effects of food components on the in vitro formation of calcium phosphate precipitates. MATERIALS AND METHODS: The effects of food components, such as starch, soybean flour, fish meal, rapeseed oil, and coconut oil, on calcium phosphate precipitation were studied using a pH drop method. RESULTS: Although the addition of starch had no effect on the rate of precipitation of amorphous calcium phosphate (ACP), it increased both the rate of transformation of ACP to hydroxyapatite (HAP) and the induction time (i.e. time for the initiation of transformation of ACP to HAP to occur); this was irrespective of the heat treatment of the starch. Amylopectin (insoluble constituent of starch) was effective in increasing the rate of HAP transformation, but amylose (soluble constituent of starch) was not. Oil specimen obtained from rapeseed (400 microl ml(-1)) increased the entire reaction of calcium phosphate precipitation, but that from coconut did not. Protein food, such as soybean flour and fish meal, decreased the rate of transformation of ACP to HAP and increased the induction time, while they had no effect on the rate of ACP precipitation. CONCLUSION: These results suggest that carbohydrate and oil (both are staple diets for the humans) enhance oral calcification (dental calculus formation or re-mineralization of tooth enamel), while side dishes of protein food would decrease it.     

壮药红根草的基原调查和生药学研究

目的对壮药红根草进行了基原调查和生药学鉴定研究。方法查阅本草文献对红根草原植物记载及附图,野外调查红根草药材的原植物来源,通过产地药农收集红根草药材原植物标本,核对药材原植物标本,咨询分类专家,对红根草的原植物形态、药材性状、显微特征、薄层色谱等进行了研究。结果目前产地及市场红根草药材原植物来源是唇形科植物黄埔鼠尾草S. prionitis带根的全草,采用建立的方法能够有效鉴别红根草药材。结论为更好地制定红根草新的药材质量标准和药厂红根草药材收购提供依据。     

植物内源激素检测方法新进展

植物内源激素是植物体内产生的一类小分子化合物,在极低的浓度下就能发挥多种生理作用,调控植物生长发育的每一过程。植物内源激素在植物体内含量极低、性质不稳定,其定量检测一直是当前研究的热点和难点。随着分析技术的进步及新仪器的出现,植物内源激素的提取和纯化技术及检测方法也在不断更新。目前,有机溶剂提取、固相萃取柱纯化是常用的提取和纯化步骤,检测方法主要包括生物鉴定法、理化检测法和免疫检测法3大类,其中理化检测是最常用方法。本文对近几年植物内源激素提取、纯化和检测方法 3个方面的新进展进行综述,以期为植物内源激素的深入研究提供参考。