叶绿体作为一种离散、高度结构化、半自主的细胞器。叶绿体的小基因组能成为合成生物学极有前途的平台。叶绿体基因工程作为一种特殊的合成生物学手段，对重建植物体内各种复杂的代谢途径具有巨大的潜力，例如提高作物的光合能力，植物的抗逆性或者合成新的药物和疫苗。然而，许多植物的叶绿体遗传转化效率低或无法进行。因此，新的转化技术和工具正在不断被开发。为了进一步拓展和促进叶绿体基因工程的应用，本文综述了近年来在叶绿体遗传转化方面的新技术，并对选择合适的合成生物元件用以构建高效的叶绿体转化载体进行了探讨。

千粒重(TGW)、穗粒数(GNS)和穗粒重(GWS)是小麦产量的重要组成部分。为了解析其遗传学基础，我们构建了一个由8762/Keyi5214衍生的198个系组成的DH群体，利用基因芯片对该DH群体进行基因型鉴定，并将产量相关性状千粒重、穗粒数和穗粒重表型整合并进行QTL定位。最后，我们共获得18,942个多态性SNP标记，并鉴定出41个与这些性状相关的关键QTL。我们在染色体2D和6A上鉴定出三个稳定的千粒重QTL (QTgw-2D.3, QTgw-2D.4, QTgw-6A.1)，其增效等位基因均来自亲本8762，解释了4.81%-18.67%的表型变异。在染色体3D、5B、5D和6A上鉴定出5个稳定的穗粒数QTL，其中QGns-5D.1来自亲本8762，其余4个来自亲本Keyi5214的QTL解释了5.89-7.08%的表型变异。此外，还发现了一个稳定的小麦穗粒重遗传位点QGws-4A.3，该位点来自亲本8762，可解释6.08-6.14%的表型变异。为了应用鉴定到的QTL，我们为四个重要的QTL (Tgw2D.3-2, Tgw2D.4-1, Tgw6A.1 和 Gns3D.1)开发了STARP标记。本研究结果可为后期小麦千粒重、穗粒数和单穗重相关基因的鉴定和克隆奠定基础。

黄花蒿是绿盲蝽重要的秋季寄主，其释放的挥发物对绿盲蝽具有吸引作用。黄花蒿中的挥发性物质青蒿酸是合成青蒿素的前体物质，在中草药领域被深入研究。迄今为止，关于青蒿酸调控绿盲蝽趋向行为的生物学作用研究鲜有报道。本研究使用顶空固相微萃取（HS-SPME）收集幼苗期黄花蒿的挥发物，通过气相色谱-质谱联用仪（GC-MS）分析，在挥发性样品和研磨样品中检测到的青蒿酸的浓度分别为11.03±6.00 ng h^-1和238.25±121.67 ng h^-1。随后，在工程酿酒酵母中表达了青蒿酸合成的关键基因细胞色素P450（cyp71av1）加入外源的青蒿醇或青蒿醛为催化底物，工程酿酒酵母能够合成青蒿酸。在触角电位（EAG）测试中，3日龄的绿盲蝽成虫对青蒿醇、青蒿醛和青蒿酸均表现出强烈的电生理反应。行为学试验表明，浓度为10 mmol L^-1的青蒿酸和青蒿醇能够显著吸引3日龄的雌性绿盲蝽虫成虫，而10 mmol L^-1 青蒿酸和青蒿醛明显吸引3日龄的雄性绿盲蝽虫成虫。 因此， 青蒿酸及其前体物质可作为潜在的绿盲蝽引诱剂组分，用于设计绿盲蝽的综合防治策略。

由于劳动力投入少、经济效益高，水稻直播已成为中国南方地区主要的种植方式。旱直播方式在单季水稻栽培技术方面运用广泛。然而，对早籼稻机械旱直播试验的研究还少有报导。通过两年大田间试验，以2个籼稻品种（中嘉早17和株两优819）为材料，研究旱直播、淹水直播和湿直播模式下的水稻倒伏特性和产量形成。结果表明，在旱直播方式下，株两优819和中嘉早17的年均产量分别比湿直播和淹水直播高14.42-26.34%和6.64-24.58%，这主要是由于穗数的提高。旱直播方式显著提高了早籼稻品种的出苗率，增加总干重和作物生长速率。同时，与淹水直播和湿直播相比，旱直播基部节间较短，茎粗和茎壁较厚，倒伏指数较低。尤其是旱直播提高了茎秆的抗倒伏能力。本研究结果表明，适宜的直播方式有利于提高早籼稻的产量和抗倒伏能力。

To date, little attention has been paid to the effects of leaf source reduction on photosynthetic matter production, root function and post-silking N uptake characteristics at different planting densities. In a 2-year field experiment, Xianyu 335, a widely released hybrid in China, was planted at 60 000 plants ha^–1 (conventional planting density, CD) and 90 000 plants ha^–1 (high planting density, HD), respectively. Until all the filaments protruded from the ear, at which point the plants were subjected to the removal of 1/2 (T1), 1/3 (T2) and 1/4 (T3) each leaf length per plant, no leaf removal served as the control (CK). We evaluated the leaf source reduction on canopy photosynthetic matter production and N accumulation of different planting densities. Under CD, decreasing leaf source markedly decreased photosynthetic rate (P_n), effective quantum yield of photosystem II (ΦPSII) and the maximal efficiency of photosystem II photochemistry (F_v/F_m) at grain filling stage, reduced post-silking dry matter accumulation, harvest index (HI), and the yield. Compared with the CK, the 2-year average yields of T1, T2 and T3 treatments decreased by 35.4, 23.8 and 8.3%, respectively. Meanwhile, decreasing leaf source reduced the root bleeding sap intensity, the content of soluble sugar in the bleeding sap, post-silking N uptake, and N accumulation in grain. The grain N accumulation in T1, T2 and T3 decreased by 26.7, 16.5 and 12.8% compared with CK, respectively. Under HD, compared to other treatments, excising T3 markedly improved the leaf P_n, ΦPSII and F_v/F_m at late-grain filling stage, increased the post-silking dry matter accumulation, HI and the grain yield. The yield of T3 was 9.2, 35.7 and 20.1% higher than that of CK, T1 and T2 on average, respectively. The T3 treatment also increased the root bleeding sap intensity, the content of soluble sugar in the bleeding sap and post-silking N uptake and N accumulation in grain. Compared with CK, T1 and T2 treatments, the grain N accumulation in T3 increased by 13.1, 40.9 and 25.2% on average, respectively. In addition, under the same source reduction treatment, the maize yield of HD was significantly higher than that of CD. Therefore, planting density should be increased in maize production for higher grain yield. Under HD, moderate decreasing leaf source improved photosynthetic performance and increased the post-silking dry matter accumulation and HI, and thus the grain yield. In addition, the improvement of photosynthetic performance improved the root function and promoted post-silking N uptake, which led to the increase of N accumulation in grain.

东北平原是中国最大的玉米产区。近年来滴灌技术开始在该区推广应用，以解决玉米生产中干旱频发和水分利用效率(WUE)低下的问题。为确定高效和环境友好的灌溉措施，2016-2018年针对滴灌结合不同农田保水措施进行了大田试验研究，处理如下：(1)塑料薄膜覆盖+滴灌(PI)，(2)生物降解膜覆盖+滴灌(BI)，(3)秸秆深翻还田+滴灌(SI)，(4)浅埋滴灌(OI)，以传统沟灌(FI)为对照。PI和BI处理根长密度(RLD)和营养生长期间土温较高，其产量、WUE和氮素利用效率(NUE)最高。与BI相比，PI处理在20-60 cm和60-100 cm土层中消耗了更多的土壤水分，且0-20 cm土壤上层根系较大，生殖生长期间土温较高，根系和叶片衰老进程加快。SI处理能有效提高土壤水分和硝态氮含量，促进深层RLD增加，从而维持了花后较高的生理活性。FI处理与滴灌相比，60-100 cm土壤深层硝态氮含量较高，增加了氮素淋溶损失的风险。0-20 cm土层中，RLD与产量、WUE和NUE极显著正相关(P<0.001)，与根系氮利用效率(NRE)显著负相关(P<0.05)，这一相关性随土层加深而减弱。在干旱条件下，降解膜覆盖与滴灌耦合有利于玉米稳产和提高土壤水氮利用效率，是一项东北区玉米可持续生产与环境友好的推荐技术。

长期秸秆还田是提高农田土壤有机碳储量的重要碳源，秸秆焚烧还田在我国南方也屡见不鲜。然而，长期稻草管理对土壤有机碳组分、酶活性及其相互关系的影响，以及其影响是否存在季节差异却尚未明确。我们基于2009年开始建立的长期定位试验平台，通过设置3个N、P、K等养分输入(包括秸秆/灰分和化学养分)的处理：秸秆不还田(CK)、秸秆还田(SR)和秸秆焚烧还田(SBR)，探讨长期秸秆还田条件对南方双季稻田土壤有机碳组分及土壤酶活性的影响。结果表明，与CK相比，长期秸秆还田有利于提高早稻产量(P=0.057)，并显著增加早晚稻田土壤的总有机碳（TOC）和微生物量碳(MBC)含量。而稻草焚烧还田对TOC无显著影响，但降低了早稻轻组有机碳（LFOC）和晚稻易氧化有机碳(EOC)含量，而显著增加了可溶性有机碳（DOC），且显著降低了土壤pH。我们研究还表明，长期秸秆还田条件下，MBC是评估双季稻系统土壤有机碳变化最敏感的指标；此外，SBR和SR对土壤酶活性的影响早晚稻稻田土壤呈现相反趋势，进而导致土壤有机碳组分含量存在季节差异，尤其是改变了土壤DOC含量，而早晚稻DOC与β-木糖苷酶均呈正相关。可见，秸秆还田较秸秆焚烧还田更有利于土壤有机碳组分的固持与提高，但其对晚稻土壤酶活性的负作用有待进一步研究。

As illustrated by the High-Level Panel of Experts on Food Security and Nutrition of the UN Committee on World Food Security (HLPE 2017), while hunger is on the rise again, malnutrition now takes multiple forms and affects all countries.  Globally, 821 million people are still undernourished (FAO et al. 2018), over 2 billion people suffer from micronutrient deficiencies, while overweight and obesity are quickly rising which affects 1.9 billion adults and 41 million children under five.
The HLPE, in many of its publications, called for radical transformations in our current food systems to address the multiple burdens of malnutrition.  There is already enough evidence to act.  The short-term cost of action may seem high, but the cost of inaction is likely to be much higher, carrying with it a terrible legacy affecting future generations.
The HLPE (2017) identified three core elements in food systems (food supply chains, food environments and consumer behaviour, see Fig. 1).  Among these three elements, the HLPE illustrated the central role of food environments in shaping consumer behaviour and food choices and, finally, in determining diets and nutrition.
The food environment refers to the “physical, economic, political and socio-cultural context in which consumers engage with the food system to make their decisions about acquiring, preparing and consuming food” (HLPE 2017).  It consists of:
• the built environment, including: the physical food entry points (supermarkets, formal and informal markets, street kiosks, food trucks, restaurants, schools, hospitals, public canteens, etc.) where food is purchased or obtained, their location and density; the physical infrastructures that allow consumers to access these points;
• the human environment, including: the personal determinants of consumer food choices (such as income, education, values, skills, etc.); and the political, social and cultural norms that influence these choices.
The food environment is a space of convergence where all actors involved in food systems, from food producers to end consumers, interact and confront their interests, objectives and strategies.  Therefore, acting on food environments in the proper way can bring transformative changes across the whole food system for delivering healthy and sustainable diets1.  More specifically, the HLPE (2017) identified three key elements of food environments on which to act to improve the diet and nutrition outcomes of our current food systems: (i) physical and economic access to food (proximity and affordability); (ii) promotion, advertising and information; (iii) food quality and safety.  Considering these three elements and recognizing the evidence gaps in our current knowledge, the HLPE (2017) explored concretely two pathways towards more sustainable food systems2 for healthier diets:
The first pathway is to improve physical and economic access to healthy diets  This first priority adopts a food system perspective.  Food supply chains impact diets and nutrition both positively and negatively.  Governments have the key responsibility to set policies, including regulations, taxes, subsidies and other forms of incentives, which enable actors in food supply chains to maximize the nutrition value of the food produced.  Government policies and programmes which specifically focus on the food environment are also key. These include: public procurement to make diverse and healthy diets more accessible and convenient3 in public places (e.g., schools, hospitals, prisons, etc.), as well as in rural marketplaces, at reasonable prices for consumers; investments and regulations (including zoning regulations) that improve the built environment; taxing junk food or sodas; regulating product formulation; regulating nutrition and health claims on food packaging; adopting an easy to interpret front-of-the-pack labelling system; limiting advertising and promotion of unhealthy foods, especially to children and adolescents; and strengthening national food safety and quality standards, etc.
This second pathway is to strengthen consumers’ information and education on healthy diets  This second priority adopts a consumer perspective and aims at creating and strengthening the demand for heathy foods.  There is a mutual relationship between food supply chains and consumer demands.  If current food supply chains largely shape consumers’ choice, consumers can also influence food supply through their behavior and demand for specific foods.  Effective regulation, information and education have the potential to orient consumers towards healthier and more sustainable food choices.  Mass media campaigns, social and behavior change communication, social media and citizen reporting, social protection programmes and food-based dietary guidelines all serve to potentially increase awareness and influence consumer dietary choices.  Yet, information and education alone may not trigger significant changes and that communication programmes must incorporate insight on actionable steps to change habits to be more effective.   When it comes to food choices, taste, convenience, cultural norms and price often prevail over health or sustainability criteria.  The most effective way to influence demand is when healthy, palatable foods are also affordable and convenient for consumers.
In conclusion, being the interface between food supply and food demand of consumers, food environments should be privileged as the policy entry point to transform our current food systems.

As an important food crop and oil crop, soybean (Glycine max [L.] Merr.) is capable of nitrogen-fixing by root nodule.  Previous studies showed that GmNMH7, a transcription factor of MADS-box family, is associated with nodule development, but its specific function remained unknown.  In this study, we found that GmNMH7 was specifically expressed in root and nodule and the expression pattern of GmNMH7 was similar to several genes involved in early development of nodule (GmENOD40-1, GmENOD40-2, GmNFR1a, GmNFR5a, and GmNIN) after rhizobia inoculation.  The earlier expression peak of GmNMH7 compared to the other genes (GmENOD40-1, GmENOD40-2, GmNFR1a, GmNFR5a, and GmNIN) indicated that the gene is related to the nod factor (NF) signaling pathway and functions at the early development of nodule.  Over-expression of GmNMH7 in hairy roots significantly reduced the nodule number and the root length.  In the transgenic hairy roots, over-expression of GmNMH7 significantly down-regulated the expression levels of GmENOD40-1, GmENOD40-2, and GmNFR5α.  Moreover, the expression of GmNMH7 could respond to abscisic acid (ABA) and gibberellin (GA₃) treatment in the root of Zigongdongdou seedlings.  Over-expressing GmNMH7 gene reduced the content of ABA, and increased the content of GA₃ in the positive transgenic hairy roots.  Therefore, we concluded that GmNMH7 might participate in the NF signaling pathway and negatively regulate nodulation probably through regulating the content of GA₃.
 

RNA interference (RNAi) technology has the potential to be used in pest management in crop production. Here, the transcriptome of Nephotettix cincticeps (Uhler) was deeply sequenced to investigate the systematic RNAi mechanism and candidate genes for dsRNA feeding. In our datasets, a total of 81 225 transcripts were obtained with the length from 150 bp to about 4.2 kb. Almost all the genes related to the RNAi core pathway were proved to be present in N. cincticeps transcriptome. Two transcripts that respectively encode a systemic interference defective (SID) were identified in our database, indicating that the systematic RNAi pathway can function effectively in N. cincticeps. Our datasets not only supply basic gene information for the studies of gene expression and functions in N. cincticeps, such as the control genes for gene expression analysis, but also provide candidate genes for RNAi pest management, such as the genes that encode P450 monooxygenase, V-ATPase and chitin synthase.

Remote sensing, in particular satellite imagery, has been widely used to map cropland, analyze cropping systems, monitor crop changes, and estimate yield and production. However, although satellite imagery is useful within large scale agriculture applications (such as on a national or provincial scale), it may not supply sufficient information with adequate resolution, accurate geo-referencing, and specialized biological parameters for use in relation to the rapid developments being made in modern agriculture. Information that is more sophisticated and accurate is required to support reliable decision-making, thereby guaranteeing agricultural sustainability and national food security. To achieve this, strong integration of information is needed from multi-sources, multi-sensors, and multi-scales. In this paper, we propose a new framework of satellite, aerial, and groundintegrated (SAGI) agricultural remote sensing for use in comprehensive agricultural monitoring, modeling, and management. The prototypes of SAGI agriculture remote sensing are first described, followed by a discussion of the key techniques used in joint data processing, image sequence registration and data assimilation. Finally, the possible applications of the SAGI system in supporting national food security are discussed.

Cry toxins produced by Bacillus thuringiensis (Bt) are effective biological insecticides against certain insect species. However, there are potential risks of the evolved resistance of insects to Cry toxin owing to decreased binding of toxins to target sites in the brush border membranes of the larva midgut. The Cry toxins with different binding sites in the larval midgut have been considered to be a good combination to deploy in delaying resistance evolution. Bioassay results demonstrated that the toxicity of different Cry toxins ranked differently for each species. The toxicity ranking was Cry1Ac>Cry1Ab>Cry2Ab for Helicoverpa armigera, Cry1B>Cry1C>Cry2Ab for Spodoptera exigua, and Cry2Ab>Cry1B> Cry1C for S. litura. Only Cry2Ab was toxic to Agrotis ipsilon. Binding experiments were performed with 125I-Cry1Ab, 125ICry1Ac, 125I-Cry1B, 125I-Cry1C, 125I-Cry2Ab and the brush border membranes vesicles (BBMV) from H. armigera, S. exigua, S. litura and A. ipsilon. The binding of Cry1Ab and Cry1Ac was shown to be saturable by incubating with increasing concentrations of H. armigera BBMV (Kd=(45.00±2.01) nmol L-1 and (12.80±0.18) nmol L-1, respectively; Bmax=(54.95±1.79) ng and (55.44±0.91) ng, separately). The binding of Cry1B was shown to be saturable by incubating with increasing concentrations of S. exigua BBMV (Kd=(23.26±1.66) nmol L-1; Bmax=(65.37±1.87) ng). The binding of 125ICry toxins was shown to be non-saturable by incubating with increasing concentrations of S. litura and A. ipsilon BBMV. In contrast, Cry1B and Cry1C showed some combination with the BBMV of S. litura, and a certain amount of Cry2Ab could bind to the BBMV of A. ipsilon. These observations suggest that a future strategy could be devised for the focused combination of specific cry genes in transgenic crops to control target pests, widen the spectrum of insecticide effectiveness and postpone insect resistance evolution.

A chemosensory protein named HarmCSP5 in cotton bollworm Helicoverpa armigera (Hübner) was obtained from antennal cDNA libraries and expressed in Escherichia coli. The real time quantitative PCR (RT-qPCR) results indicated that HarmCSP5 gene was mainly expressed in male and female antennae but also expressed in female legs and wings. Competitive binding assays were performed to test the binding affinity of recombinant HarmCSP5 to 60 odor molecules including some cotton volatiles. The resules showed that HarmCSP5 showed strong binding abilities to 4-ehtylbenzaldehyde and 3,4-dimethlbenz aldehyde, whereas methyl phenylacetate, 2-decanone, 1-pentanol, carvenol, isoborneol, nerolidol, 2- nonanone and ethyl heptanoate have relatively weak binding affinity. Moreover, the predicted 3D model of HarmCSP5 consists of six α-helices located among residues 33-38 (α1), 40-48 (α2), 62-72 (α3), 80-96 (α4), 98-108 (α5), and 116-119 (α6), two pairs of disulfide bridges Cys49-Cys55, Cys75-Cys78. The two amino acid residues, Ile94 and Trp101, may play crucial roles in HarmCSP5 binding with ligands and need further study for confirmation.

Cry toxins produced by Bacillus thuringiensis (Bt) are effective biological insecticides against certain insect species. In this study, bioassay results indicated that Cry1B and Cry1C were toxic to Spodoptera exigua. We also identified a cadherin-like gene in S. exigua that could enhance the toxicity of Cry1B and Cry1C. The cadherin-like gene identified from the larvae midgut tissue was cloned by reverse transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). The full-length cDNA of the gene consisted of 5 220 bp encoding 1 740 amino acid with a predicted molecular mass of 196 kD. BLAST search analysis showed that the predicted amino acid sequence had a high sequence identity to the published sequences of cadherin-like proteins from other Lepidoptera insects. Spatial expression of the cadherin-like gene detected by qRT-PCR analysis revealed that the cadherin-like gene was mainly present in the gut of 4th instar larvae and during different life stages. The results suggested that the commercial development of this synergist has the potential to enhance Cry1B and Cry1C toxicity against Lepidoptera insects.

Cuscuta campestris, a dodder, can parasitize and suppress a scrambling herbaceous to semi-woody perennial vine, Mikania micrantha, one of the most destructive weeds in the world. To assess the effects of the mixed residue of C. campestris and M. micrantha on the subsequent plant community, we conducted a one-year experiment on the germination and seedling growth of subsequent plant community after the application of C. campestris. Seven treatments of varying proportions of C. campestris and M. micrantha residue on 21 subject trees and shrubs, which were commonly found in South China, resulted in a germination rate of 35.3% for all 8715 seeds from 18 species, ranging from 5.7 to 81.9%; the remaining 3 species failed to germinate. ANOVA analysis showed that the residue did not affect the germination, growth, or mortality of the trees and shrubs. The germinated C. campestris seeds from the residue coiled the seedlings of most of the species, but less than 4% host death caused by C. campestris. In addition, the residue did not affect the germination of the herbaceous seedlings originating from the loam, and the similarity coefficients of the germinated seedlings between the treatments were very high. These results suggested that the residue had no negative impact on the germination and early seedling stages of the tree, shrub and grass species of the subsequent plant community. The use of C. campestris residue had a positive effect on the growth of M. micrantha, but it did not change the trend of M. micrantha being suppressed because re-parasitization occurred soon after the growth restarted. No negative effect was detected on the other species as a result of the parasitization of C. campestris or by the use of the mixed residue. This suggests that C. campestris is likely to be an effective and promising ecologically safe native herbaceous agent for controlling M. micrantha.