OVEREXPRESSION OF PTRLEA7, A LATE EMBRYOGENESIS ABUNDANT FAMILY GENE FROM PONCIRUS TRIFOLIATA, CONFERS ENHANCED DROUGHT TOLERANCE BY ENHANCING ANTIOXIDANT CAPACITY

• A LEA family gene (PtrLEA7)was cloned from Poncirus trifoliata. • PtrLEA7was strongly induced by stresses and ABA. • PtrLEA7played a positive role in modulation of drought tolerance. • Overexpression of PtrLEA7elevated antioxidant capacity. Late embryogenesis abundant (LEA) genes encode highly hydrophilic proteins that are essential in abiotic stress responses. However, most LEA genes in higher plants have not yet been investigated. This study identified an LEA family gene (PtrLEA7) from Poncirus trifoliata and studied its function in drought tolerance. The full-length coding sequence of PtrLEA7 was 420 bp encoding a protein of 139 amino acids. Phylogenetic analysis shows that PtrLEA7 protein belongs to the LEA_4 subfamily. Expression profiling by qPCR found that PtrLEA7 was strongly induced by dehydration, cold and ABA treatments, and slightly induced by salt stress. Subcellular localization reveals that PtrLEA7 protein was located in both cytoplasm and nucleus. To investigate its function, transgenic plants of both tobacco and Poncirus trifoliata overexpressing PtrLEA7 were obtained. Stress tolerance assays show that overexpression lines had enhanced dehydration and drought tolerance compared with wild type plants, indicating that PtrLEA7 positively regulates drought tolerance. In addition, transgenic plants had much higher expression levels of three antioxidant enzyme genes (CAT, SOD and POD) and significantly increased catalase enzyme activity, accompanied by reduced reactive oxygen species accumulation in comparison with wild type plants. Collectively, this study demonstrates that PtrLEA7 can confer enhanced drought tolerance partially via enhancing antioxidant capacity.     

BULKED SEGREGANT RNA SEQUENCING (BSR-SEQ) IDENTIFIES A NOVEL ALLELE ASSOCIATED WITH WEEPING TRAITS IN PRUNUS MUME

• Five QTLs associated with weeping traits on chromosome 7 were identified by BSR-seq. • The novel allele PmUGT72B3 has a synonymous transition of T⁶⁶ (upright) to C (weeping) in the coding sequence and a 470-bp deletion in the promoter region. • PmUGT72B3 was associated with hormone and lignin regulation by WGCNA. Weeping species are used both as ornamental plants and for breeding dwarf plant types. However, exploration of casual genes controlling weeping traits is rather limited. Here, we identified individuals with contrasting phenotypes from an F₁ bi-parental mapping population of Prunus mume which was developed from a cross between the upright cultivar ‘Liuban’ and the weeping cultivar ‘Fentai Chuizhi’. Bulked segregant RNA sequencing was used and five QTLs on Chromosome 7 were identified. The Pm024074 (PmUGT72B3) allele, belonging to the UDP-glycosyltransferase superfamily containing the coniferyl-alcohol glucosyltransferase domain, was identified in a genomic region overlapping with a previously identified QTL, and had a synonymous transition of T⁶⁶ (upright) to C (weeping) in the coding sequence and a 470-bp deletion in the promoter region. Pm024074 had exceptionally high expression in buds and stems of weeping P. mume. Weighted correlation network analysis indicates that genes neighboring Pm024074 were significantly associated with plant architecture. In addition, a reliable single nucleotide polymorphism marker was developed based on the variation in the Pm024074 gene, providing precise marker-assisted breeding for weeping traits. This study provides insights into the genetic mechanism governing the weeping trait in P. mume, and indicates potential applications for the manipulation of tree architecture.     

A CASE FOR ASSESSING ALLOCASUARINA AND CASUARINA SPP. FOR USE IN AGROECOSYSTEM IMPROVEMENT IN SEMI-ARID AREAS WITH A FOCUS ON CENTRAL ANATOLIA,TURKEY

• Semi-arid ecosystems have been especially impacted by a long history of clearing, cropping and intensified grazing. • Selection of tree species for assessment for agroforestry needs to consider their utility and effectiveness in provision of ecosystem service, but also the wider consideration of preserving biodiversity. • Imperatives of agroecosystem services and biodiversity conservation (or restoration) will impact on species selection for agroforestry. • The potential of Allocasuarina and Casuarina for wider economic and ecosystem needs an endeavor to achieve demonstrable gains. Agroecosystems in water-limited contexts— Mediterranean, semi-arid and arid climatic zones—are too frequently degraded systems that will not provide the needed ecosystem services to ensure a future of sustainable agricultural production. The processes that have created this situation continue and are being accelerated by anthropogenic climate change. Increasing arboreal vegetation in these areas through agroforestry is an important strategy to conserve and improve their agroecosystems. Actinorhizal trees and shrubs in the Casurinaceae have a unique set of adaptations for heat and water stress, and/or infertile to hostile soils. Central Anatolia, Turkey is particularly at risk of increasing aridity and further degradation. Therefore, species of Allocasuarina and Casuarina have been evaluated for their potential use in agroecosystem improvement in semi-arid areas with a focus on Central Anatolia. Based on a semiquantitative environmental tolerance index and reported plant stature, eight species were identified as being of high (A. verticillata and C. pauper) to moderate (A. acutivalvis, A. decaisneana, A. dielsiana, A. huegeliana, C. cristata and C. obesa) priority for assessment, with none of these species having been adequately evaluated for agroforestry deployment in semi-arid agroecosystems in any context.     

COMPARING PERFORMANCE OF CROP SPECIES MIXTURES AND PURE STANDS

•The literature on intercropping comprises thousands of papers. •Evidence synthesis is needed to develop general conclusions. •Quantitative evidence synthesis requires meaningful comparative performance metrics. •The background, meaning, and limitations of some performance metrics is explained. •Future challenges are identified. Intercropping is the planned cultivation of species mixtures on agricultural land. Intercropping has many attributes that make it attractive for developing a more sustainable agriculture, such as high yield, high resource use efficiency, lower input requirements, natural suppression of pests, pathogens and weeds, and building a soil with more organic carbon and nitrogen. Information is needed which species combinations perform best under different circumstances and which management is suitable to bring out the best from intercropping in a given production situation. The literature is replete with case studies on intercropping from across the globe, but evidence synthesis is needed to make this information accessible. Meta-analysis requires a careful choice of metric that is appropriate for answering the question at hand, and which lends itself for a robust meta-analysis. This paper reviews some metrics that may be used in the quantitative synthesis of literature data on intercropping.     

COMPARISON OF POMELO (CITRUS MAXIMA) GROWN IN CHINA AND THAILAND

• China is the largest producer of pomelo globally. • Chinese pomelos are adapted to subtropical climates and Thai pomelos to tropical climates. • Guanxi pomelo is a popular cultivar in China and Thong Dee is the most popular in Thailand. • Naringin is the most abundant flavonoid in Chinese and Thai pomelos. • Fruity, sweet, sour, juicy and overall flavor attributes are important in consumer preference. Pomelo is a member of the genus Citrus that is a key contributor to the breeding of modern citrus cultivars. China is the largest producer of pomelo and one of the top five pomelo exporting countries. Pomelos from Thailand are also well-known for their excellent quality and flavor and are ranked in the top ten export countries. This review introduces pomelo planting locations and conditions in China and Thailand. The characteristics and qualities of some commercial pomelo cultivars in China and Thailand are summarized to introduce them to international consumers and to document their similarities and dissimilarities. Data on bioactive compounds and antioxidant capacity are also included for most Chinese and Thai pomelos to highlight how they differ in this aspect because consumers are increasingly interested in healthier foods. In addition, the sensory perception in terms of aroma, flavor, texture and taste attributes and consumer perspective and preferences are discussed.     

IN VITRO ACTIVITY OF EXTRACTS OF FIVE MEDICINAL PLANT SPECIES ON PLANT PATHOGENIC FUNGI

• Ethyl acetate and 95% ethanol extracts from T. chinensis rhizomes gave great inhibition on six plant pathogenic fungi • T. chinensis has potential to be a new natural fungicide resource • T. chinensis has potential to be used for the preservation of agricultural and forestry products such as fruits and vegetables The antifungal effectiveness of extracts of five medicinal plant species was determined. The inhibitory activity of extracts of Eucalyptus tereticornis, Xanthium sibiricum, Artemisia argyi, Tupistra chinensis and Pyrola calliantha were evaluated against the mycelial growth of the plant pathogenic fungi Aspergillus niger, Botrytis cinerea, Penicillium digitatum, P. expansum, P. italicum and Rhizopus stolonifer. All plant extracts were prepared at 60°C using solvents (either water, 50% ethanol (v/v), 95% ethanol (v/v), ethyl acetate or petroleum ether). Fungicidal effects of all plants tested were confirmed. Different extracts from the same plant species gave different degrees of inhibition. All aqueous extracts had weak or no activity on all fungi tested. Ethyl acetate and 95% ethanol extracts from T. chinensis rhizomes gave greater inhibition and a broader spectrum inhibition than the other extracts. T. chinensis may have potential as a new natural fungicide and may be used for the preservation of agricultural and forestry products such as fruits and vegetables.     

EXTRACTION AND EVALUATION OF EDIBLE OIL FROM SCHIZOCHYTRIUM SP. USING AN AQUEOUS ENZYMATIC METHOD

• Aqueous enzymatic extraction (AEE) is performed for oil extraction from Schizochytrium sp. • AEE process is optimized by response surface methodology. • Microalgal oil extracted by AEE has high contents of PUFA, tocopherols and phenolics. • AEEO exhibits considerable antioxidant activity as compared with SEO. Schizochytrium sp., a marine microalga, is a potential source of edible oil due to its short growth cycle and rapid lipid accumulation, especially of docosahexaenoic acid. An approach to isolate edible microalgal oil from Schizochytrium sp. using aqueous enzymatic extraction (AEE) was developed. Parameters were optimized by single-factor experiments followed by Box-Behnken design. Proteases were effective in extracting oil. The maximum free oil recovery (49.7%±0.58%) and total oil recovery (68.1%±0.94%) were obtained under optimum conditions of liquid-to-solid ratio of 4.8:1, a 2.5% enzyme concentration of papain and an extraction time of 2.2 h. There was a significant difference (P<0.05) in polyunsaturated fatty acid composition between microalgal oil obtained by AEE and by Soxhlet extraction, with the former having superior physiochemical properties and higher concentrations of bioactive components including total phenolic compounds and total tocopherols. These findings indicate a potential application of AEE for extraction of oil from Schizochytrium sp.     

BIOINSECTICIDES AS FUTURE MAINSTREAM PEST CONTROL AGENTS: OPPORTUNITIES AND CHALLENGES

•Wide use of botanical insecticides is limited by the availability of certain plants. •Studies are needed to improve RNAi efficiency and to assess their safety risk. •Microbial insecticides are promising, but they only control a narrow range of pests. •Multitarget approach should be a promising strategy in future pest control. •Nanoformulation could enhance stability and control the release of bioinsecticides. Bioinsecticides are naturally-occurring substances from different sources that control insect pests. Ideal bioinsecticides should have low toxicity to non-target organisms. They should also be easily degraded in sewage treatment works and natural environments, highly effective in small quantities and affect target pests only. Public concerns about possible side-effects of synthetic pesticides have accelerated bioinsecticide research and development. However, to develop bioinsecticides into mainstream products, their high production costs, short shelf-life and often uncertain modes of action need to be considered. This review summarizes current progress on bioinsecticides which are categorized as biochemical insecticides and their derivatives, plant-incorporated protectants, and microbial bioinsecticides. The current constraints that prevent bioinsecticides from being widely used are discussed and future research directions are proposed.     

WHEAT STRIPE RUST AND INTEGRATION OF SUSTAINABLE CONTROL STRATEGIES IN CHINA

• Stripe rust caused substantial yield losses in China. • P. striiformis is highly variable and the change from avirulence to virulence. • Different comprehensive control strategies were adopted in different epidemic region. Stripe (yellow) rust caused by Puccinia striiformis f. sp. tritici occurs in almost all wheat-producing regions of the world. Severe countrywide epidemics in China have caused substantial yield losses. Growing resistant cultivars is the best strategy to control this disease but the pathogen can overcome resistance in wheat cultivars. The high variation in the virulence of the pathogen combined with the large areas of susceptible wheat cultivars enables the pathogen population to increase rapidly and disperse over long distances under favorable environmental conditions, resulting in severe pandemics within cropping seasons. Current stripe rust control measures are based on many years of research including the underlying epidemiology regarding year-to-year survival of the pathogen, pathways of pathogen dispersal within seasons and years, the role of P. striiformis sexual hybridization, the use of resistance sources in breeding programs, and year-round surveillance of national wheat crops that are present in different parts of the country throughout the year. All these strategies depend on accurate prediction of epidemics, more precise use of fungicides to meet national requirements and better deployment of resistance genes. New ideas with potential application in sustainable protection of stripe rust include negative regulatory gene editing, resistance gene overexpression and biological control based on microbiomes.     

ROUTE DEVELOPMENT,ANTIVIRAL STUDIES,FIELD EVALUATION AND TOXICITY OF AN ANTIVIRAL PLANT PROTECTANT NK0238

• Developed a two-step synthetic route to anti-plant-virus candidate NK0238. • NK0238 exhibited a broad antivirus spectrum in greenhouse. • NK0238 showed comparable antivirus activities as controls in field trials. • NK0238 was safe to birds, fish, bees and silkworms. • NK0238 has a very good prospect in commercial development. It has previously been shown that tryptophan, the biosynthesis precursor of Peganum harmala alkaloids, and its derivatives have anti-TMV activity both in vitro and in vivo. Further exploration of this led to the identification of NK0238 as a highly effective agent for the prevention and control of diseases caused by plant viruses, but the existing routes are unsuitable for its large-scale synthesis. This study optimized a route for two-step synthesis of this virucide candidate via reaction of l-tryptophan with triphosgene to produce l-tryptophan-N-carboxylic anhydride, which then reacts with n-octylamine to give NK0238 at up to 94% yield and nearly 97% HPLC purity. In addition, the route was used for the preparation of NK0238 on a>40 g scale permitting further assessment of its antivirus activity in the greenhouse and field experiments, and toxicity tests. NK0238 exhibited useful antiviral activities against a variety of viruses both in greenhouse and field experiments. The toxicity tests showed that NK0238 was not acutely toxic to birds, fish, honey bees and silkworms. The optimized route provides a solid foundation for its large-scale synthesis and subsequent efficacy and toxicity studies, its excellent activity and safety make NK0238 a promising drug candidate for further development.     

DISCOVERY OF TRIKETONE-QUINOXALINE HYBRIDS AS POTENT HPPD INHIBITORS USING STRUCTURE-BASED DRUG DESIGN

• HPPD is one of the most promising targets for new herbicides. • A family of novel HPPD inhibitors based on the triketone-quinoxaline scaffold was designed and synthesized. • One particular product (7d) gave the highest inhibition of HPPD of the newly synthesized derivatives. • Triketone-quinoxaline derivatives provide a useful molecular scaffold for the discovery of novel HPPD-inhibiting herbicides. p-Hydroxyphenylpyruvate dioxygenase (EC 1.13.11.27, HPPD) belongs to the family of Fe(II)-dependent non-heme oxygenases that occur in the majority of aerobic organisms. HPPD has proved to be a promising target in herbicide research and development. A battery of novel triketone-quinoxaline compounds has been designed using a structure-based drug design strategy and then prepared. Enzyme inhibition assays show that these synthesized derivatives possess favorable inhibition capability against Arabidopsis thaliana HPPD with IC₅₀ values ranging from 0.317 to 0.891 μmol·L⁻¹. Subsequently, the molecular docking results indicate that two adjacent carbonyls of the triketone moiety of the representative compound 2-(2,3-dimethyl-8-(o-tolyl)quinoxaline-6-carbonyl)-3-hydroxycyclohex-2-en-1-one (7d) engage in chelation with the ferrous ion of A. thaliana HPPD in a bidentate pose, and its quinoxaline scaffold forms two sets of parallel π-stacking interaction between two phenylalanine residues (Phe424 and Phe381). In addition, the extended phenyl group also interacts with Phe392 in a π-π stacking way. This study indicates that triketone-quinoxaline is a promising scaffold for discovering HPPD inhibitors with substantially increased potency, providing insight into the molecular design of new herbicides.     

EFFECT OF SOLARIZATION TO KILL BRADYSIA CELLARUM ON CHINESE CHIVE GROWTH AND SOIL MICROBIAL DIVERSITY

• Soil solarization achieved 100% control of Bradysia cellarum. • The initial growth of Chinese chive was lower in solarized than control plots, but 20 d after treatment plants in the solarized had recovered and leaf height and yield were equivalent among the treatments. • Soil microbial community diversity in the treatment group first decreased and then recovered gradually, and abundance of beneficial microorganisms increased significantly. Bradysia cellarum Frey (Diptera: Sciaridae) is an important subterranean pest and is especially damaging to Chinese chive. An effective and more environmentally safe method than pesticides is needed for its control. The efficacy of B. cellarum control, growth of Chinese chive and soil microbial diversity were investigated after uae of soil solarization to exterminate this insect pest. The results show that on the first day after soil solarization 100% control of B. cellarum was achieved. Growth of Chinese chive was lower in solarized plots than in control plots over the first 10 d after treatment. Chive growth in solarized plots increased subsequently to match that in the control plots. Moreover, the soil microbial community diversity in the treatment group decreased initially before gradually recovering. In addition, the abundance of beneficial microorganisms in the genus Bacillus and the phyla Proteobacteria, Chloroflexi and Firmicutes increased significantly. Soil solarization is therefore practical and worthy of promotion in Chinese chive-growing regions.     

THE ANTHOCYANIN BIOSYNTHETIC REGULATOR MDMYB1 POSITIVELY REGULATES ASCORBIC ACID BIOSYNTHESIS IN APPLE

• The contents of anthocyanin and AsA in red-flesh apples are higher than that in non-red-flesh apples. • The anthocyanin biosynthetic regulator MdMYB1 directly activates the expression of dehydroascorbate reductase gene MdDHAR, thus promoting the activity of the DHAR enzyme and the accumulation of AsA. • MdMYB1-MdDHAR module may play a key role in AsA-DHA homeostasis. Ascorbic acid (AsA, vitamin C) is involved in the regulation of many aspects of plant growth and development. It is an essential micronutrient for humans and can prevent scurvy, maintain the health of gums and blood vessels, reduce the level of plasma cholesterol and enhance the immune systen. Apple cultivars Orin and Guanghui were crossed to obtain a group of hybrid offspring with and without red flesh in the course of assessing apple germplasm resources. Unexpectedly, the red-flesh apples had higher AsA contents than other apples. Further studies showed that the anthocyanin biosynthetic regulator MdMYB1 directly activates the expression of dehydroascorbate reductase gene MdDHAR, thus promoting the activity of the DHAR enzyme and the accumulation of AsA. This finding reveals the mechanism leading to high AsA levels in red-flesh apples and suggests a new idea to cultivate red-flesh apples with high AsA contents and produce AsA efficiently and without pollution.     

INTENSIFICATION OF GRASSLAND-BASED DAIRY PRODUCTION AND ITS IMPACTS ON LAND,NITROGEN AND PHOSPHORUS USE EFFICIENCIES

• Monitoring data of>5000 dairy farms collected and examined in uniform manner. • Environmental performances of farms influenced by government regulations. • N and P surpluses at farm level remained about constant with intensity level. • N and P use efficiencies at farm, herd and soil increased with intensity level. • Accounting for externalization of off-farm feed production affects NUE and PUE. • Ammonia emissions per kg milk decreased with the level of intensification. Many grassland-based dairy farms are intensifying production, i.e., produce more milk per ha of land in response to the increasing demand for milk (by about 2% per year) in a globalized market. However, intensive dairy farming has been implicated for its resources use, ammonia and greenhouse gas emissions, and eutrophication impacts. This paper addresses the question of how the intensity of dairy production relates to N and P surpluses and use efficiencies on farms subjected to agri-environmental regulations. Detailed monitoring data were analyzed from 2858 grassland-based dairy farms in The Netherlands for the year 2015. The farms produced on average 925 Mg·yr⁻¹ milk. Milk production per ha ranged from<10 to>30 Mg·ha⁻¹·yr⁻¹. Purchased feed and manure export strongly increased with the level of intensification. Surpluses of N and P at farm level remained constant and ammonia emissions per kg milk decreased with the level of intensification. In conclusion, N and P surpluses did not differ much among dairy farms greatly differing in intensity due to legal N and P application limits and obligatory export of manure surpluses to other farms. Further, N and P use efficiencies also did not differ among dairy farms differing in intensity provided the externalization of feed production was accounted for. This paper provides lessons for proper monitoring and control of N and P cycling in dairy farming.     

WATER USE IN HUMAN CIVILIZATIONS: AN INTERDISCIPLINARY ANALYSIS OF A PERPETUAL SOCIAL-ECOLOGICAL CHALLENGE

• Access to water shapes determines rise and collapse of civilizations • Water conservation, human health and culture are closely connected • Agricultural intensification triggers multiple cropping, irrigation and fertilization • Mastering access to water will determine pace and sustainability of urbanization Settlement patterns and social structures have been shaped by access to water since the onset of human societies. This review covers historical and recent examples from Cambodia, Central Asia, India, Latin America and the Arabian Peninsula to analyze the role of water resources in determining the rise and collapse of civilizations. Over recent decades increasing globalization and concomitant possibilities to externalize water needs as virtual water have obscured global dependence on water resources via telecoupling, but rapid urbanization brings it now back to the political agenda. It is foremost in the urban arena of poorer countries where competing claims for water increasingly lead to scale-transcendent conflicts about ecosystem services. Solutions to the dilemma will require broad stakeholder-based agreements on water use taking into account the available data on water resources, their current and potential use efficiency, recycling of water after effective treatment, and social-ecological approaches of improved governance and conflict resolution.     

GREEN AGRICULTURE AND BLUE WATER IN CHINA: REINTEGRATING CROP AND LIVESTOCK PRODUCTION FOR CLEAN WATER

• AGD aims for a green environment, sustainable agriculture and clean water. • Presenting examples of the impact of agriculture on water quality. • Presenting examples of solutions for sustainable agriculture and improved water quality. • Integration of livestock and cropping systems is possible on a farm or among farms. • Providing recommendations for further development of sustainable agriculture. Crop and livestock production are essential to maintain food security. In China, crop and livestock production were integrated in the past. Today, small backyard systems are still integrated but the larger livestock farms are landless and largely geographically separated from crop production systems. As a result, there is less recycling of animal manures and there are lower nutrient use efficiencies in the Chinese food production systems. This, in turn, results in considerable losses of nutrients, causing water pollution and harmful algal blooms in Chinese lakes, rivers and seas. To turn the tide, there is a need for agricultural “green” development for food production through reintegrating crop and livestock production. An additional wish is to turn the Chinese water systems “blue” to secure clean water for current and future generations. In this paper, current knowledge is summarized to identify promising interventions for reintegrating crop and livestock production toward clean water. Technical, social, economic, policy and environmental interventions are addressed and examples are given. The paper highlights recommended next steps to achieve “green” agriculture and “blue” water in China.