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2018 Vol. 17 No. 07 Previous Issue    Next Issue

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Review
Special Focus: Regularity of population occurrence and migration in the oriental armyworm, Mythimna separata (Walker)
Crop Science
Horticulture
Animal Science · Veterinary Medicine
Food Science
Short Communication


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The oriental armyworm, Mythimna separata (Walker), a typical long-distance migratory insect, is a major, polyphagous pest of grain crops in China and other Asian countries. With the recent adjustment in agricultural planting structure in China and global climate change, the regularity of occurrence within regions seems to be changing as well. JIA organized this special focus on the progress of population occurrence and migration regularity, including M. separata closely related species biology, migration energy from nectar plants, trajectory analysis of migration route, and immigrant habitat environment influence and resistance identification. Several related armyworm species often co-infest fields with M. separata, introducing complications in monitoring and forecasting owing to sparse knowledge of their basic biology. Access to nectar plants during migration is a prerequisite for adult long-distance migration and reproduction, and their distribution provides clues to the armyworm migration pathway. Population data and trajectory analysis provide technical support for fine-scale forecasting of outbreaks. Habitat environment such as host plant, weed coverage and temperature affect population abundance and occurrence, and taking them into account can benefit development of new agronomic management tactics. Monitoring insecticide resistance is of immediate importance in developing effective integrated pest management strategies for this insect. Cover photo is provided by Prof. JIANG Xing-fu, Institute of Plant Protection, Chinese Academy of Agricultural Sciences.


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Physiological mechanism underlying spikelet degeneration in rice WANG Zhi-qin, ZHANG Wei-yang, YANG Jian-chang 2018, 17(07): 1475-1481.  DOI: 10.1016/S2095-3119(18)61981-1 Abstract ( )   PDF (716KB) ( )   The phenomenon of degenerated spikelets is very common in cereals, and considered as a serious physiological defect and a main constraint to grain production.  Understanding the physiological mechanism in which spikelet degeneration occurs would have great significance in enhancing yield potential in grain crops.  Taking rice as an example, the paper reviewed the physiological mechanism underlying spikelet degeneration, with focus on the roles of phytohormones in regulating the process.  There are several hypotheses for the spikelet degeneration, such as resource limitation, self-organization, and primigenic dominance.  However, convincing evidences are not enough to support the assumptions.  Phytohormones including auxins, cytokinins, gibberellins, abscisic acid, and ethylene are involved in regulating spikelet degeneration in cereals.  The new phytohormones of brassinosteroids and polyamines have been observed to suppress spikelet degeneration in rice.  The interactions among or between plant hormones may play a more important role in regulating spikelet degeneration.  However, the information on such interactions is very limited.  Some agronomic practices, especially proper water and nitrogen management, could reduce spikelet degeneration but the mechanism underlying remains unclear.  Further research is needed to understand the cross-talk among/between phytohormones on spikelet degeneration, to reveal the physiological and molecular mechanism in which phytohormones and their interactions regulate the degeneration of spikelets, to exploit approaches to decrease spikelet degeneration and to elucidate their mechanism.

Special Focus: Regularity of population occurrence and migration in the oriental armyworm, Mythimna separata (Walker)

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Editorial JIANG Xing-fu 2018, 17(07): 1482-1484.  DOI: 10.1016/S2095-3119(18)62013-1 Abstract ( )   PDF (300KB) ( )   The oriental armyworm, Mythimna separata (Walker) (Lepidoptera: Noctuidae), is a major migrant pest of grain in China and other Asian countries, causing huge crop production and economic losses nationwide annually.  Much of the uniquely difficult aspects of managing M. separata arises from its long-distance migratory behavior.  For example, direction and timing of winds from its overwintering regions in the south largely determine where and when large influxes of migrants arrive in the north to oviposit, making prediction of infestations difficult.  Since the 1960s, the migration routes and infestation patterns of M. separata in China have been resolved (Li et al. 1964; Jiang et al. 2011), allowing development of effective forecasting and early warning technology to help manage this insect.  Over the past two decades, large-scale outbreaks of M. separata have rarely occurred.  However, in 2012, M. separata infested much of northern and northeastern China. ...... We hope that the readers will find the articles in this special focus informative and useful for oriental armyworm pest management.  We are grateful to the authors and anonymous reviewers.  We thank Editorial Board and Editor-in-Chief of the Journal of Integrative Agriculture for accepting our proposal to publish these papers.  We also thank the special fund for Agro-scientific Research in the Public Interest of China (201403031) for support of this special focus.

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Migratory flight of insect pests within a year-round distribution: European corn borer as a case study Thomas W. Sappington 2018, 17(07): 1485-1506.  DOI: 10.1016/S2095-3119(18)61969-0 Abstract ( )   PDF (548KB) ( )   Insect migratory flight differs fundamentally from most other kinds of flight behavior, in that it is non-appetitive.  The adult is not searching for anything, and migratory flight is not terminated by encounters with potential resources.  Many insect pests of agricultural crops are long-distance migrants, moving from lower latitudes where they overwinter to higher latitudes in the spring to exploit superabundant, but seasonally ephemeral, host crops.  The migratory nature of these pests is somewhat easy to recognize because of their sudden appearance in areas where they had been absent only a day or two earlier.  Many other serious pests survive hostile winter conditions by diapausing, and therefore do not require migration to move between overwintering and breeding ranges.  Yet there is evidence of migratory behavior engaged in by several pest species that inhabit high latitudes year-round.  In these cases, the consequences of migratory flight are not immediately noticeable at the population level, because migration takes place for the most part within their larger year-round distribution.  Nevertheless, the potential population-level consequences can be quite important in the contexts of pest management and insect resistance management.  As a case study, I review the evidence for migratory flight behavior by individual European corn borer adults, and discuss the importance of understanding it.  The kind of migratory behavior posited for pest species inhabiting a permanent distribution may be more common than we realize.

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Effects of temperatures on the development and reproduction of the armyworm, Mythimna roseilinea: Analysis using an age-stage, two-sex life table QIN Jian-yang, LIU Yue-qiu, ZHANG Lei, CHENG Yun-xia, LUO Li-zhi, JIANG Xing-fu 2018, 17(07): 1506-1515.  DOI: 10.1016/S2095-3119(17)61856-2 Abstract ( )   PDF (1156KB) ( )   The armyworm Mythimna roseilinea (Walker) is a major pest of grain crops in South China.  So far little is known about its basic biology and ecology, making prediction of population dynamics difficult.  This study examined the relationships of individual development and population growth with temperature based on an age-stage, two-sex life table of M. roseilinea reared on maize in the laboratory at 18, 21, 24, 27 and 30°C.  The highest values of net reproductive rate (R0) and fecundity were observed at 21 and 24°C, respectively.  Both the intrinsic rate of increase (r) and finite rate of increase (λ) increased significantly and mean generation time (T) decreased significantly with increasing temperature.  M. roseilinea was able to develop, survive and lay eggs at all temperature regimes tested.  Development rates of the egg, larval, pupal, as well as the whole pre-oviposition stages had a positive linear relationship with temperature.  The calculated development threshold temperatures of egg, larval, pupal, pre-oviposition and total pre-oviposition stages were 13.29, 8.39, 14.35, 7.42, and 12.24°C, respectively, and their effective accumulated temperatures were 63.59, 445.00, 211.11, 89.02, and 698.95 degree-days, respectively.  These results provide insight into temperature-based phenology and population ecology of this insect pest and will allow population prediction and management available in the field.

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Identification of summer nectar plants contributing to outbreaks of Mythimna separata (Walker) (Lepidoptera: Noctuidae) in North China GUO Pei, WANG Gao-ping, JIN Li-jie, FAN Xing-qi, HE Han-lin, ZHOU Pei-wen, GUO Xian-ru, LI Wei-zheng, YUAN Guo-hui 2018, 17(07): 1516-1526.  DOI: 10.1016/S2095-3119(17)61840-9 Abstract ( )   PDF (5911KB) ( )   The presence of adequate nectar sources along the migratory pathway is a prerequisite for moths of oriental armyworm, Mythimna separata, to reach target habitats and lay eggs.  Identification of plant species and assessment of their suitability as wild nectar sources along the summer migration pathway of adult M. separata are critical steps in making effective forecasts of second- and third-generation armyworm outbreaks in North China.  We explored five aspects of moth-nectar source relationships: (1) Field investigations in 2014 and 2015 showed that the florescence of chaste tree, Vitex negundo var. heterophylla, a primary nectar plant in apiculture, coincided with the summer migration of oriental armyworm moths.  The flowers of chaste tree opened day and night and M. separata moths were found actively flying around and resting on tree.  (2) Identification of moth-borne pollen by scanning electronic microscopy (SEM) micrographs in 2015 and 2016 revealed that 15.4% of 369 moths trapped by blacklight traps, 17.1% of 557 moths captured by vertical-pointing searchlight traps and 24.4% of 311 moths caught by pheromone traps were found with pollen attached to their proboscis.  A total of 228 pollen-carrying individuals out of 1 237 armyworm moths were captured by the three types of traps.  The three highest percentages of pollen-bearing armyworm moths were carrying pollen of Toona sp. (59.65%), Ligustrum sp. (27.19%) and Syringa sp. (4.39%).  In total, 14 types of pollen were detected where three were identified to species, 10 to genus and one as an unknown species.  (3) Analysis of geographical distribution, flowering periods and relative abundances of candidate nectar plants suggested that Chinese toon, Toona sinensis, and privet, Ligustrum lucidum, were two important nectar plant species.  (4) Analysis on relationship between pollen and ovarian development showed that 14, 15 and 10 females carrying pollen of T. sinensis had ovaries at developmental stages I, II and III, respectively.  Many T. sinensis pollen grains were present on the proboscises of female moths.  (5) Comparison of trap effectiveness between blacklight and vertical-pointing searchlight traps indicated blacklight traps caught the highest proportion (35.2%) of female in ovarian stage V, whereas vertical-pointing searchlight traps caught the highest proportion (43.5%) of female in ovarian stage I with additional proportions of decreasing percentages for stages II, III and IV.  Integrated analysis on these five aspects suggests that T. sinensis is an important, suitable summer nectar source that potentially influences migration and reproduction of M. separata moths and thus contributes to outbreaks of this pest.  The vertical-pointing searchlight trap was the most effective tool for monitoring the migratory flight of adult M. separata.  Privet, Ligustrum lucidum, and clove, Syringa sp., are possible suitable summer nectar plants that need further study to elucidate their importance.  The reason why field investigation results on chaste tree differed from the results of moth-borne pollen analyses was discussed.

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Analysis on the migration of first-generation Mythimna separata (Walker) in China in 2013 ZHANG Zhi, ZHANG Yun-hui, WANG Jian, LIU Jie, TANG Qing-bo, LI Xiang-rui, CHENG Deng-fa, ZHU Xun 2018, 17(07): 1527-1537.  DOI: 10.1016/S2095-3119(17)61885-9 Abstract ( )   PDF in ScienceDirect   Mythimna separata (Walker) is an important pest which can cause serious damages to cereal crops.  In the past two decades, several heavy outbreaks have taken place in northern China.  In order to develop a fine-scale method of forecasting outbreaks, population data were collected in northern China using searchlight traps and ground light traps.  A background weather pattern analysis and trajectory analysis were performed via the Weather Research and Forecast (WRF) and FLEXPART models.  Our results showed that heavy migration of first-generation M. separata appeared in northern China in 2013.  In Yanqing District, Beijing, the cumulative number of captured adults in searchlight traps was around 250 000 and the daily maximum for trapped moths was 86 000.  During the peak period, the majority of M. separata moths arrived after 00:00 every night.  The sex ratio (female:male) at each monitoring site was greater than 1 and greatly fluctuated with population dynamics.  During the migration peak, prevailing downdraft winds benefited M. separata moths to land passively.  Trajectory simulation showed that immigrants were from Anhui, Jiangsu and Hubei provinces and most of them could continue to fly into the northeastern regions of China.  These results provide technical support for fine-scale forecasting of the outbreak of M. separata at meso- and micro-scale.

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Association of host plant growth and weed occurrence with armyworm (Mythimna separata) damage in corn fields ZHANG Kun-peng, YU Zhi-hao, JIANG Shi-xiong, SUN De-wen, HUI Jun-tao, ZHENG Yu-liang, LI Xiao-zhen, WANG Xing-yun, WU Jun-xiang 2018, 17(07): 1538-1544.  DOI: 10.1016/S2095-3119(17)61857-4 Abstract ( )   PDF in ScienceDirect   To clarify association between armyworm (Mythimna separata) damage level and the corn growth and weed occurrence, we investigated corn plant height, stem diameter and vigor as well as weed coverage and biomass.  The investigations were conducted at three locations of Shaanxi Province, China which were suffered seriously from armyworm.  Significant correlations were found between the parameters analyzed.  At stunted corn growth and presence of plenty of weeds, the armyworm damage tended to be heavy; oppositely, when corn grew well and weed density were low, armyworm harm was the minimal.  Therefore, corn growing status and weed density can significantly affect armyworm damage level.  Our results imply that promoting corn growth and timely removal of weeds are conducive to reducing armyworm occurrence.

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Effects of constant and stage-specific-alternating temperature on the survival, development and reproduction of the oriental armyworm, Mythimna separata (Walker) (Lepidoptera: Noctuidae) LI Bo-liao, XU Xiang-li, JI Jia-yue, WU Jun-xiang 2018, 17(07): 1545-1555.  DOI: 10.1016/S2095-3119(17)61841-0 Abstract ( )   PDF in ScienceDirect   Migratory insects make diverse adaptive strategies in response to changes in external environment.  Temperature has an impact on the survival, development, reproduction, and migration initiation of insects.  Previous research has primarily been focused on the effects of constant temperature on populations, but changing temperature has received less attention.  Three constant temperature treatments (20, 25 and 30°C) and three pupal-alternating temperature treatments (20–25, 25–20 and 25–30°C) were set up to study the relationship between temperature and population development by age-stage, two-sex life table analysis in the oriental armyworm, Mythimna separata Walker, a notorious migratory pest in grain crops.  The 25°C treatment was considered optimal with 20 and 30°C as low suitable temperature and high temperatures, respectively.  The survival rate was relatively low before third instar larvae at  20°C (63.0%) and 20–25°C (70.1%), and extreme low after pupal stage at 30°C (20.6%).  Developmental duration of each stage was negatively correlated with temperature.  The adult pre-oviposition period, when most migratory insects initiate migration, was the shortest at 25°C (2.69 d) but was lengthened at both low suitable (7.48 d for 20°C, 6.91 d for 25–20°C and 4.57 d for 20–25°C) and high temperatures (3.74 d for 25–30°C and 5.00 d for 30°C).  Both low suitable and high temperature decreased lifetime fecundity, net reproductive rate and the intrinsic rate of increase, with variability observed across developmental duration and stage during non-optimal temperature.  The results expand knowledge of the relationship between changing temperature and armyworm population development, and adaptive strategies in complex ambient environment.

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Insecticide resistance of the field populations of oriental armyworm, Mythimna separata (Walker) in Shaanxi and Shanxi provinces of China ZHAO Yu-yu, SU Li, LI Shuai, LI Yi-ping, XU Xiang-li, CHENG Wei-ning, WANG Yi, WU Jun-xiang 2018, 17(07): 1556-1562.  DOI: 10.1016/S2095-3119(17)61787-8 Abstract ( )   PDF in ScienceDirect   Resistance of five field populations of Mythimna separata (Walker) collected from Shaanxi and Shanxi provinces of China to six different insecticides was evaluated by leaf dip method in the laboratory.  The results showed that all populations were relatively sensitive to emamectin benzoate with a resistance ratio (RR) of 0.583–1.583 folds.  All populations showed susceptible or low level resistance to chlorantraniliprole and beta-cypermethrin.  Compared with a relatively susceptible strain of M. separata, the resistance level of the whole populations ranged from susceptible to moderate to chlorpyrifos and lambda-cyhalothrin, moderate to high to phoxim (RR=19.367–70.100) except for population from Sanyuan County (RR=2.567).  Pair-wise correlation analysis among different insecticides indicated that chlorpyrifos has a significantly positive and significant correlation with emamectin benzoate.  Chlorantraniliprole didn’t have significant correlation with emamectin benzoate, chlorpyrifos and phoxim.  Therefore, emamectin benzoate, chlorantraniliprole and beta-cypermethrin are recommended to control oriental armyworm.  Meanwhile, to postpone the occurrence and development of insecticide resistance in Shaanxi and Shanxi provinces, alternative and rotational application of insecticides between chlorantraniliprole and emamectin benzoate or chlorpyrifos is necessary.

Crop Science

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Identification of QTLs associated with cadmium concentration in rice grains HU Da-wei, SHENG Zhong-hua, LI Qian-long, CHEN Wei, WEI Xiang-jin, XIE Li-hong, JIAO Gui-ai, SHAO Gao-neng, WANG Jian-long, TANG Shao-qing, HU Pei-song 2018, 17(07): 1563-1573.  DOI: 10.1016/S2095-3119(17)61847-1 Abstract ( )   PDF in ScienceDirect   Cadmium (Cd) contamination in rice has been a hot topic of research because of its potential risk to human health.  In this study, a double haploid (DH) population derived from Zhongjiazao 17 (YK17) (an early-season indica cultivar)×D50 (a tropical japonica cultivar) was used to identify quantitative trait loci (QTLs) associated with Cd concentration in brown rice (CCBR) and Cd concentration in milled rice (CCMR).  Continuous and wide variation for CCBR and CCMR were observed among the DH population.  Correlation analysis revealed a positive and highly significant correlation between the two traits.  A total of 18 QTLs for CCBR and 14 QTLs for CCMR were identified in five different pot and field trials.  Two pairs of QTLs for CCBR (qCCBR2-1 and qCCBR2-2, qCCBR9-1 and qCCBR9-2) and one pair of QTLs for CCMR (qCCMR5-1 and qCCMR5-2) were detected in multiple trials.  The alleles increasing CCBR at the qCCBR2-1/qCCBR2-2 and qCCBR9-1/qCCBR9-2 QTLs were contributed by YK17 and D50, respectively, whereas the D50 allele at the qCCMR5-1/qCCMR5-2 QTLs increased CCMR.  Eight pairs of QTLs for CCBR and CCMR, qCCBR2-2 and qCCMR2-2, qCCBR3 and qCCMR3, qCCBR4-2 and qCCMR4-1, qCCBR4-3 and qCCMR4-2, qCCBR4-4 and qCCMR4-3, qCCBR5 and qCCMR5-2, qCCBR7 and qCCMR7, and qCCBR11-1 and qCCMR11-2, co-localized on chromosomes 2, 3, 4, 5, 7, and 11, respectively.  For all of these QTL pairs, except qCCBR5/qCCMR5-2, the additive effects came from YK17.  In addition, four CCMR QTLs showing significant additive×environment interaction and two pairs of CCMR QTLs with bi-allelic epistatic interactions were identified.  The results of this study could facilitate marker-assisted selection of breeding rice varieties with low Cd accumulation in grain.

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Unravelling transcriptome changes between two distinct maize inbred lines using RNA-seq ZHOU Yu-qian, WANG Qin-yang, ZHAO Hai-liang, GONG Dian-ming, SUN Chuan-long, REN Xue-mei, LIU Zhong-xiang, HE Hai-jun, QIU Fa-zhan 2018, 17(07): 1574-1584.  DOI: 10.1016/S2095-3119(18)61956-2 Abstract ( )   PDF in ScienceDirect   Seed size play a significant role in maize yield production.  Two maize inbred lines with distinct seed size and weight, V671 (a large-seed inbred line) and Mc (a small-seed inbred line), were investigated by RNA-seq at 14 days after pollination (DAP), when maize endosperm undergoes an active transition from mitosis to storage accumulation.  RNA-seq expression data showed that the small-seed line Mc had a higher storage accumulation activity, whereas the large-seed kernel line V671 possessed a higher DNA synthesis activity.  An investigation of the pattern of increasing kernel width at serial DAPs showed that V671 experienced an increased kernel width later than did Mc, but the rate and duration of increase were longer in V671.  SDS-PAGE of the storage proteins and quantitative RT-PCR of cell cycle-related genes and indole-3-acetic (IAA) synthesis genes certified that the transition from mitosis to storage accumulation starts earlier in Mc.  We hypothesized that the difference in the mitosis-to-storage accumulation transition accounts for the larger seed size in V671 vs. Mc.

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Genetic analysis of the maximum germination distance of Striga under Fusarium oxysporum f. sp. strigae biocontrol in sorghum Emmanuel Mrema, Hussein Shimelis, Mark Laing, Learnmore Mwadzingeni 2018, 17(07): 1585-1593.  DOI: 10.1016/S2095-3119(17)61790-8 Abstract ( )   PDF in ScienceDirect   Maximum germination distance (MGD) is an important component of Striga resistance in sorghum.  The objective of this study was to determine gene action influencing MGD of Striga hermonthica and Striga asiatica among selected sorghum lines treated with a biocontrol agent, Fusarium oxysporum f. sp. strigae (FOS) for effective breeding with Striga resistance, and FOS compatibility.  Twelve sorghum genotypes were selected based on their Striga resistance, FOS compatibility, and superior agronomic performance.  Selected genotypes were crossed using a bi-parental mating design to generate six families for genetic analysis.  Agar-gel assays were used to determine low haustorium initiation factor (LHF) using the 12 parental lines, their F1 progenies, backcross derivatives, and F2 segregants in two sets.  One set had S. hermonthica seed and the other one had S. asiatica seed.  Both were treated with and without FOS.  Genotypes were evaluated using a split-plot design with three replications and MGD data were recorded followed by generation mean analysis.  FOS reduced MGD by 1 cm under both S. hermonthica and S. asiatica infestations.  Additive, dominance, and epistatic gene actions were involved in the control of MGD of the two Striga species in the evaluated populations.  On average, the relative contribution of additive, additive×additive and dominance×dominance genetic effects on the MGD of S. hermonthica and S. asiatica, with FOS, were 20, 33, and 36%; and 21, 32, and 35%, respectively.  Breeding methods exploiting these genetic effects may provide enhanced response to selection for Striga resistance and FOS compatibility in integrated Striga management (ISM) programmes.

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Effect of shade stress on lignin biosynthesis in soybean stems LIU Wei-guo, REN Meng-lu, LIU Ting, DU Yong-li, ZHOU Tao, LIU Xiao-ming, LIU Jiang, Sajad Hussain, YANG Wen-yu 2018, 17(07): 1594-1604.  DOI: 10.1016/S2095-3119(17)61807-0 Abstract ( )   PDF in ScienceDirect   To clarify how shade stress affects lignin biosynthesis in soybean stem, two varieties, Nandou 12 (shade tolerant) and Nan 032-4 (shade susceptible) grew under normal light and shade conditions (the photosynthetically active radiation and the ratio of red:far-red were lower than normal light condition).  Lignin accumulation, transcripts of genes involved in lignin biosynthesis, and intermediates content of lignin biosynthesis were analyzed.  Both soybean varieties suffered shade stress had increased plant heights and internode lengths, and reduced stem diameters and lignin accumulation in stems.  The expression levels of lignin-related genes were significantly influenced by shade stress, with interactions between the light environment and variety.  The gene of 3-hydroxylase (C3H), cinnamoyl-CoA reductase (CCR), caffeoyl-CoA O-methyltransferase (CCoAOMT), and peroxidase (POD) attributed to lignin biosynthesis under shade stress, and the down-regulation of these genes resulted in lower caffeic, sinapic, and ferulic acid levels, which caused a further decrease in lignin biosynthesis.  Under shade stress, the shade tolerant soybean variety (Nandou 12) showed stiffer stems, higher lignin content, and greater gene expression level and higher metabolite contents than shade susceptible one.  So these characteristics could be used for screening the shade-tolerant soybean for intercropping.

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Studying the physiological and yield responses of sunflower inbred lines to full and limited irrigation Nasserghadimi Farshad, Jahanbakhsh Soodabeh, Ghaffari Mehdi, Ebadi Ali 2018, 17(07): 1605-1611.  DOI: 10.1016/S2095-3119(17)61823-9 Abstract ( )   PDF in ScienceDirect   In order to study the physiological and yield responses of sunflower inbred lines to full and limited irrigation, an experiment was conducted in the growing season of 2014–2015 in the research field of the Agricultural Research Station in Khoi, Iran.  Water withholding was imposed in the flowering stages from R4 (initial flowering) to R6 (full flowering).  The results showed that the main effect of irrigation and inbred lines and the interaction effect between irrigation and inbred lines in terms of the proline and protein contents, the catalase, peroxidase, and polyphenol oxidase activities, and seed yield in all inbred lines, and relative water content (RWC) were significant at 1% level.  Water withholding in the flowering stage increased the proline content and the catalase, peroxidase, and polyphenol oxidase activities, whereas limited irrigation decreased the protein content and seed yield in all inbred lines and RWC.  The lowest protein content and the highest catalase, peroxidase, and polyphenol oxidase activities were observed in BGK 39 under limited irrigation condition, while BGK 37 revealed the highest proline content in such circumstances.  The highest seed yield was seen in BGK 1 and BGK 375 in full irrigation condition.  Limited irrigation increased the proline content by 49.51%, compared to that of full irrigation condition.

Horticulture

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An EMS mutant library for cucumber CHEN Chen, CUI Qing-zhi, HUANG San-wen, WANG Shen-hao, LIU Xiao-hong, LU Xiang-yang, CHEN Hui-ming, TIAN Yun 2018, 17(07): 1612-1619.  DOI: 10.1016/S2095-3119(17)61765-9 Abstract ( )   PDF (25875KB) ( )   Cucumber is an important vegetable crop and a model crop for the study of sex expression in plants.  However, the genomic resources and tools for functional genomics studies in cucumber are still limited.  In this paper, we conducted ethyl methyl sulfone (EMS) mutagenesis in the northern China ecotype cucumber inbred line 406 to construct a mutant library.  We optimized the conditions of EMS mutagenesis on inbred line 406 which included treatment of seeds at 1.5% EMS for 12 h.  We obtained a number of mutant lines showing inheritable morphological changes in plant architecture, leaves, floral organs, fruits and other traits through M1, M2 and M3 generations.  The F2 segregating populations were constructed and analyzed.We found that a short fruit mutant and a yellow-green fruit peel mutant were both under the control of a single recessive gene, respectively.  These results provide valuable germplasm resources for the improvement of cucumber genetics and functional genomic research.

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Effects of leaf removal and cluster thinning on berry quality of Vitis vinifera cultivars in the region of Weibei Dryland in China SONG Chang-zheng, WANG Chao, XIE Sha, ZHANG Zhen-wen 2018, 17(07): 1620-1630.  DOI: 10.1016/S2095-3119(18)61990-2 Abstract ( )   PDF in ScienceDirect   Leaf removal and cluster thinning were carried out prior to veraison to evaluate the effects on berry quality of two Vitis vinifera cultivars (Cabernet Sauvignon and Ugni Blanc) in the Weibei Dryland of China in 2013 and 2014, and comprehensive analysis of the chemical and volatile composition in berries was performed.  The results showed that content of reducing sugar in both varieties was not affected while total acid was generally decreased by leaf removal and cluster thinning.  The pH of berry juice was correspondingly higher in most treatment groups.  Meanwhile, promoting effects on accumulation of total phenols, tannin in both varieties and total anthocyanins in Cabernet Sauvignon were found.  As for monomeric anthocyanins, percentage of malvidin and its derivatives was decreased by leaf removal and cluster thinning.  Besides, cinnamylated anthocyanins decreased with the intensity of cluster thinning.  The accumulation of non-anthocyanin phenolics was similarly affected in the two varieties.  Notably, cluster thinning was more effective on enhancing the phenolics content than leaf removal.  The combination of middle level of leaf removal and cluster thinning was the most favor to the accumulation of phenolic acids.  Furthermore, cluster thinning could also significantly enhance the synthesis of flavanols and stilbenes.  Lastly, content and variety of aroma compounds in both grape varieties were also significantly affected by the treatments.  The results provided a theoretical basis for a combination of leaf removal and cluster thinning to improve quality of grapes and wines.

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Light shading improves the yield and quality of seed in oil-seed peony (Paeonia ostii Feng Dan) HAN Chen-jing, WANG Qi, ZHANG Hong-bao, WANG Shou-hai, SONG Hua-dong, HAO Jian-mei, DONG He-zhong 2018, 17(07): 1631-1640.  DOI: 10.1016/S2095-3119(18)61979-3 Abstract ( )   PDF (254KB) ( )   Tree peony seed is unique for its super-high content of unsaturated fatty acid and is thus considered as an important source of woody oil. However, photosynthetic production is greatly reduced under high light intensity and air temperature during the seed filling period, which negatively affects seed yield and quality. The objective of this study was to determine if appropriate shading improves yield and quality of seed in oilseed peony. In this study, oilseed peony trees were shaded by different density polyethylene nets from four weeks after flowering to harvest stages to form light, moderate, and severe shadings, equivalent to about 80, 40, and 20% of full solar exposure, respectively. The effects of different shadings on some physiological parameters, yield and yield components, and nutritional composition of seed were examined. Averaged across two years, light shading increased the actual net photosynthetic rate (Pn) by 16.8%, the maximum net photosynthetic rate (Pmax) by 81.4%, chlorophyll (Chl) content by 52.8%, auxin (IAA) content by 38.1%, and gibberellic acid (GA3) content in leaves by 6.3%; it decreased the accumulation of H2O2 in leaves by 24.8%, malondialdehyde (MDA) by 22%, and endogenous abscisic acid (ABA) by 8.8%, indicating that leaf senescence in late season was considerably delayed. Light shading increased seed yield, and contents of crude fat and unsaturated fatty acids by 9.7, 5.6, and 9.6%, respectively, while moderate or severe shading significantly reduced all the three parameters. Light shading increased seed weight, but moderate or severe shading reduced seed weight or follicle density. The improved seed yield under light shading was mainly due to increased seed weight, while the reduced seed yield under moderate or severe shading was mainly attributed to reduce follicle density and seed weight. The improved seed weight and content of unsaturated fatty acids under light shading was possibly due to the delayed leaf senescence. The overall results indicated that light shading is beneficial to yield and quality parameters of seed in oilseed peony. Cultivating oilseed peony under a light shading environments such as partially closed forests would better increase total output and income per unit land area than that under full solar exposure.

Animal Science · Veterinary Medicine

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Update of Meat Standards Australia and the cuts based grading scheme for beef and sheepmeat Sarah P. F. Bonny, Rachel A. O’Reilly, David W. Pethick, Graham E. Gardner, Jean-Fran?ois Hocquette, Liselotte Pannier 2018, 17(07): 1641-1654.  DOI: 10.1016/S2095-3119(18)61924-0 Abstract ( )   PDF (565KB) ( )   Changing markets and evolving consumer demand present new challenges for the beef and sheep industries.  In response, the industry has been investing in innovations to deliver new products and management systems to consumers.  One such innovation is the Meat Standards Australia (MSA) system.  This system is a Total Quality Management System, aimed at delivering an eating quality guarantee to consumers, and through this adding value to the entire supply chain.  At present, it is well developed for beef and still evolving for sheepmeat.  MSA has identified Critical Control Points (CCPs) in the production, pre-slaughter, processing and value-adding aspects of the supply chain that impact on consumer palatability through the large-scale taste testing of meat by untrained consumers.  These CCPs are used as either (1) mandatory criteria determining eligibility for grading, and (2) inputs in a model predicting the palatability of individual combinations of muscle and different cooking methods.  Through the prediction of palatability, MSA increases consumer satisfaction and is used to provide assurance for branded products and new marketing innovations in Australia and internationally.  This has added significant value to the Australian beef industry, with several retail examples demonstrating consumer willingness to pay more for premium quality beef and sheepmeat products based on the MSA grading scores.  This price differential at retail allows the value of the carcass to be calculated based on the eating quality as well as the volume produced, thereby delivering a financial reward for farmers producing high quality carcasses.  The continuous quality scale of MSA allows producers to realise the financial gain of incremental improvements in quality, as well as the precise economic weights associated with traits such as marbling, ossification score, or breed.  The use of MSA in this fashion has underpinned a new and innovative supply chain where the pricing is transparent and allows producers to make informed decisions to modify both quality and yield traits.  To date, the MSA system for beef has proved to be effective in predicting beef palatability not only in Australia but also in many other countries (France, Poland, Ireland, Northern Ireland, Japan, South Korea, New-Zealand, the USA and South Africa).  In Europe, results of the ProSafeBeef and ProOptiBeef projects as well as other national projects demonstrate the potential to develop an MSA-like international grading system for the supply chain in the EU, despite the diverse cultures and complex beef production systems within the member states.  International testing in lamb has only just begun and preliminary results are discussed here.

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Insertion site of FLAG on foot-and-mouth disease virus VP1 G-H loop affects immunogenicity of FLAG ZHU Yuan-yuan, ZOU Xing-qi, BAO Hui-fang, SUN Pu, MA Xue-qing, LIU Zai-xin, FAN Hong-jie, ZHAO Qi-zu 2018, 17(07): 1655-1666.  DOI: 10.1016/S2095-3119(18)61916-1 Abstract ( )   PDF (2175KB) ( )   The G-H loop of the foot-and-mouth disease virus (FMDV) virion contains certain dominant immunogenic epitopes, as well as an arginine-glycine-aspartic acid (RGD) motif that is recognized by cell surface integrin receptors.  Previous experiments indicate that it is critical to maintain virus structural integrity when inserting an exogenous epitope into the surface of an FMDV structural protein.  However, it remains to be determined how factors such as different insertion positions affect interactions among the virus, cells and host immune system.  In this study, one infectious cDNA clone of the swine FMDV Cathay topotype strain O/CHA/90 was constructed.  Then, a FLAG marker (DYKDDDDK) was inserted upstream (–4) or downstream (+10) of the RGD motif to generate tagged viruses vFLAG-O/CHA/90 or vO/CHA/90-FLAG, investigating the possibility of expressing foreign antigen and effect on its immunogenicity.  Compared to the parental virus, both tagged viruses exhibited similar plaque phenotypes, suckling mouse pathogenicity and antigenicity.  Additionally, the FLAG tag insertion position did not change the use of integrin-mediated cell entry by the tagged viruses.  Interestingly, both tagged vaccines protected pigs against challenge with the parental virus O/CHA/90 and induced immune responses against FMDV in BALB/c mice and pigs, but only vaccination with vFLAG-O/CHA/90 generated anti-FLAG antibodies.  Our findings demonstrated that two sites (RGD–4 and RGD+10) tolerated the insertion of an exogenous gene in the swine FMDV O/CHA/90 strain.  However, only RGD–4 was a novel and appropriate inserting site which could tolerate exogenous FLAG.  The resultant tagged virus is a promising candidate for FMD vaccine which can be differentiating infected from vaccinated animals (DIVA).

Food Science

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Effects of 1-methylcyclopropene and modified atmosphere packaging on fruit quality and superficial scald in Yali pears during storage FENG Yun-xiao, CHENG Yu-dou, HE Jin-gang, LI Li-mei, GUAN Jun-feng 2018, 17(07): 1667-1675.  DOI: 10.1016/S2095-3119(18)61940-9 Abstract ( )   PDF in ScienceDirect   The Yali pear (Pyrus bretschneideri Rehd.) is susceptible to superficial scald during prolonged cold storage and at shelf life.  This study investigated the effects of 1-methylcyclopropene (1-MCP) and modified atmosphere packaging (MAP) on changes of fruit quality and superficial scald during cold storage and at shelf life in Yali pear.  Compared with MAP, the combination of MAP and 1-MCP (MAP+1-MCP) treatment reduced the carbon dioxide and ethylene content inside the packaging bag.  The 1-MCP, MAP, and MAP+1-MCP treatments reduced the superficial scald index, malondialdehyde content, O2–· production rate and relative conductivity and inhibited the accumulation of α-farnesene and conjugated trienes in the peel.  1-MCP and MAP+1-MCP treatments maintained a higher phenolic content and enhanced the catalase and superoxide dismutase activities in the fruit, while reduced activities of lipoxygenase and polyphenol oxidase in the peel preceding the onset of superficial scald.  Comprehensive analysis indicated that the MAP+1-MCP treatment is the most effective method tested for improving the quality of Yali pears during cold storage and at shelf life.

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Multi-mycotoxin exposure and risk assessments for Chinese consumption of nuts and dried fruits WANG Yu-jiao, NIE Ji-yun, YAN Zhen, LI Zhi-xia, CHENG Yang, Saqib Farooq 2018, 17(07): 1676-1690.  DOI: 10.1016/S2095-3119(18)61966-5 Abstract ( )   PDF in ScienceDirect   In this study, 15 mycotoxins were detected in 233 nut and dried fruit samples from China.  The 15 mycotoxins included aflatoxins (AFs: AFB1, AFB2, AFG1 and AFG2), trichothecene toxins (TCs: T-2, ZEA, ENA, ENA1, ENB, ENB1 and BEA), Alternaria toxins (ATs: TEN, AOH and AME) and ochratoxin A (OTA).  The mycotoxins were detected in 47.6% of the samples and all 15 of the mycotoxins were found.  Two samples were positive for AFB1 and exceeded the maximum tolerable levels allowed in China.  The contamination levels of the mycotoxins found in nuts, dried jujubes, raisins, dried figs and dried longans were in the ranges of 0.1–462.7, 0.2–247.3, 0.8–10.1, 0.2–384.1 and 0.1–89.2 μg kg–1, respectively.  Dried figs (80.0%) had the highest incidence of mycotoxins, followed by dried longans (60.0%), dried jujubes (57.1%), nuts (43.6%) and raisins (26.7%).  The estimated daily intake (EDI) values of each individual mycotoxin and all of the mycotoxins collectively were calculated by both the deterministic approach (DA) and the probability approach (PA).  For risk characterization, dietary exposure to TCs, ATs and OTA through consumption of nuts and dried fruits according to both approaches, showed no health risk to Chinese adults by exposure to either individual mycotoxins or in combination.  To the best of our knowledge, this is the first work in which risk assessment of multimycotoxins is performed, specifically including the emerging ENNs and BEA, in nuts and dried fruits of China.

Short Communication

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Characterisation of pH decline and meat color development of beef carcasses during the early postmortem period in a Chinese beef cattle abattoir ZHANG Yi-min, David L. Hopkins, ZHAO Xiao-xiao, Remy van de Ven, MAO Yan-wei, ZHU Li-xian, HAN Guang-xing, LUO Xin 2018, 17(07): 1691-1695.  DOI: 10.1016/S2095-3119(17)61890-2 Abstract ( )   PDF in ScienceDirect   This study investigated the pH/temperature decline of beef carcasses in a typical Chinese abattoir and color development as pH declined during rigor onset.  A natural cubic spline model was used to model the pH/temperature decline for those carcasses which passed through pH 6.0.  Six of the 97 carcasses that exhibited a high (≥6.10) ultimate pH (pHu) (dark-cutting) in the M. longissimus lumborum (LL) were sampled, along with the same numbers of normal pHu and intermediate pHu carcasses (5.40–5.79; 5.80–6.10, respectively), to examine color development within 24 h postmortem.  It was shown that 66.7% of the modeled carcasses were outside the ideal pH/temperature window with a temperature@pH6.0 lower than ideal, suggesting the need for acceleration of the pH decline.  The stable and low a*, b* and chroma values of high pHu beef within the first 12 h indicated dark-cutting beef might be detected earlier than expected.