2019 Vol. 18 No. 3 Previous Issue    Next Issue

    Crop Science
    Plant Protection
    Agro-ecosystem & Environment
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    Evolution of varieties and development of production technology in Egypt wheat: A review
    Kishk Abdelmageed, CHANG Xu-hong, WANG De-mei, WANG Yan-jie, YANG Yu-shuang, ZHAO Guang-cai, TAO Zhi-qiang
    2019, 18(3): 483-495.  DOI: 10.1016/S2095-3119(18)62053-2
    Abstract ( )   PDF (1668KB) ( )  
    Wheat was the first crop grown in Egypt, and it remains highly important.  Egypt is the largest wheat importer in the world and consumes an extensive amount of bread.  It is imperative for wheat scientists to decrease the large gap between production and consumption.  Wheat yields in Egypt increased 5.8-fold (6.7 billion kg) between 1961 and 2017 due to variety improvement and the use of better planting methods such as the raised bed method, ideal sowing date, surge flow irrigation and farm irrigation systems, laser levelling, fertilizers, and intercropping with raised beds.  In this paper, the development of wheat production techniques and variety evolution over more than five decades in Egypt have been analyzed.  In particular, we have focused on the technologies, cultural practices and causes for per unit area yield increase.  The main purpose was to study the issues that have arisen during wheat production and to make recommendations for smart agricultural practices.  In 1981, the yield was 3 300 kg ha–1 and through the improvement of varieties, expansion of agricultural land and the adoption of modern agricultural techniques yield reached 6 500 kg ha–1 by 2017.  The production growth rate was 4.1% annually, and the total grain yield increased 4.3-fold, from 1.9 billion kg in 1981 to about 8.1 billion kg in 2017.  The use of new improved varieties, new cultivation techniques, and modern irrigation techniques contributed to 97.0% of the increase in yield per unit area and 1.5% of the increase in yield was due to planting area expansion.  Therefore, the increase in total yield mainly depended on the increase in yield per unit area.  Wheat production in Egypt has been improved through the development of breeding and cultivation techniques.  The use of these new techniques, the popularization of new high-quality seed varieties, and the use of the raised bed method instead of the old method of planting in basins have made the largest contributions to increased yield.  In the future, wheat yield could be further increased by using the tridimensional uniform sowing mode and the development of wheat varieties that are resistant to rusts, deficit irrigation, and abiotic stress, that are highly adaptable to mechanized operation and have high yields.  Based on our analysis, we propose the main technical  requirements and measures to increase wheat yield in Egypt in the near future.
    Weak stem under shade reveals the lignin reduction behavior
    Sajad Hussain, Nasir Iqbal, PANG Ting, Muhammad Naeem Khan, LIU Wei-guo, YANG Wen-yu
    2019, 18(3): 493-505.  DOI: 10.1016/S2095-3119(18)62111-2
    Abstract ( )   PDF (712KB) ( )  
    Shades caused by neighboring tall plants in intercropping systems and weak sunlight are constraints in yield optimization.  Shade influences many aspects of plant growth and development, leading to weak stems and susceptibility to lodging.  The plant cell wall is composed of certain proteins that allow the walls to stretch out, a process called cell wall loosening.  Shade affects anatomical, morphological, and physiological traits of plants, thus reducing the physical strength of the stem in crops by changing the loosening of cell walls.  Flexibility of cells facilitates further modifications such as wall loosening.  In addition, shade stress causes increased internode length, and reduced xylem synthesis and photosynthesis.  In shaded plants, lignin deposition in vascular bundles and sclerenchyma cells of stems is decreased.  Lignin is a light sensitive phenolic compound and shading decreases the transcript abundance of several phenolic compound (flavone and lignin) related genes.  Shading significantly influences the metabolic activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD), 4-coumarate: CoA ligase (4CL), and cinnamyl alcohol dehydrogenase (CAD) involved in lignin biosynthesis.  Furthermore, suppression of lignin biosynthesis activities by abiotic stresses causes abnormal phenotypes such as collapsed xylem, bent stems, and growth retardation.  In this review, the underlying mechanisms illustrate that under shading conditions reduced lignin content results in slender, weak, and unstable stems.  The objective of this review is to elaborate lignin biosynthesis and its variability under stressful environmental conditions, especially in shade stress environments.  The effects of shade on stem lignin metabolism are discussed on the morphogenetic, physiological, and proteomic levels.
    Research advances of SAR remote sensing for agriculture applications: A review
    LIU Chang-an, CHEN Zhong-xin, SHAO Yun, CHEN Jin-song, Tuya Hasi, PAN Hai-zhu
    2019, 18(3): 506-525.  DOI: 10.1016/S2095-3119(18)62016-7
    Abstract ( )   PDF (343KB) ( )  
    Synthetic aperture radar (SAR) is an effective and important technique in monitoring crop and other agricultural targets because its quality does not depend on weather conditions.  SAR is sensitive to the geometrical structures and dielectric properties of the targets and has a certain penetration ability to some agricultural targets.  The capabilities of SAR for agriculture applications can be organized into three main categories: crop identification and crop planting area statistics, crop and cropland parameter extraction, and crop yield estimation.  According to the above concepts, this paper systematically analyses the recent progresses, existing problems and future directions in SAR agricultural remote sensing.  In recent years, with the remarkable progresses in SAR remote sensing systems, the available SAR data sources have been greatly enriched.  The accuracies of the crop classification and parameter extraction by SAR data have been improved progressively.  But the development of modern agriculture has put forwarded higher requirements for SAR remote sensing.  For instance, the spatial resolution and revisiting cycle of the SAR sensors, the accuracy of crop classification, the whole phenological period monitoring of crop growth status, the soil moisture inversion under the condition of high vegetation coverage, the integrations of SAR remote sensing retrieval information with hydrological models and/or crop growth models, and so on, still need to be improved.  In the future, the joint use of optical and SAR remote sensing data, the application of multi-band multi-dimensional SAR, the precise and high efficient modeling of electromagnetic scattering and parameter extraction of crop and farmland composite scene, the development of light and small SAR systems like those onboard unmanned aerial vehicles and their applications will be active research areas in agriculture remote sensing.  This paper concludes that SAR remote sensing has great potential and will play a more significant role in the various fields of agricultural remote sensing. 
    Crop Science
    Identification and QTL mapping of Z550, a rice backcrossed inbred line with increased grains per panicle
    WANG Shi-ming, CUI Guo-qing, WANG Hui, MA Fu-ying, XIA Sai-sai, LI Yun-feng, YANG Zheng-lin, LING Ying-hua, ZHANG Chang-wei, HE Guang-hua, ZHAO Fang-ming
    2019, 18(3): 526-531.  DOI: 10.1016/S2095-3119(18)61996-3
    Abstract ( )   PDF (310KB) ( )  
    An elite backcrossed inbred line Z550 with increased grains per panicle was identified from advanced backcrosses between Nipponbare and Xihui 18 by simple sequence repeat (SSR) marker-assisted selection (MAS).  Z550 carries 13 substitution segments distributed on chromosomes 1, 6, 7, 8, 9, 10, and 12, with an average substitution length of 1.68 Mb.  Compared with the Nipponbare parental line, plant height, panicle length, spikelets per panicle, grains per panicle, and grain weight for Z550 were significantly increased.  While the grain width of Z550 was significantly narrower, and the seed setting ratio (81.43%) was significantly lower than that of Nipponbare, it is still sufficient for breeding purposes.  Quantitative trait loci (QTLs) mapping for important agronomic traits was conducted with the F2 population derived from Nipponbare crossed with Z550 using the restricted maximum likelihood (REML) method.  A total of 16, including 12 previously unreported QTLs were detected, with contribution rates ranging from 1.46 to 10.49%.  Grains per panicle was controlled by 8 QTLs, 5 of which increased number of grains whereas 3 decreased it.  qGPP-1, with the largest contribution (10.49%), was estimated to increase grains per panicle by 30.67, while qGPP-9, with the minimum contribution rate (2.47%), had an effect of increasing grains per panicle by 15.79.  These results will be useful for further development of single segment substitution lines with major QTLs, and for research of their molecular functions via QTL cloning.
    Genetic mapping and expressivity of a wheat multi-pistil gene in mutant 12TP
    ZHU Xin-xin, NI Yong-jing, HE Rui-shi, JIANG Yu-mei, LI Qiao-yun, NIU Ji-shan
    2019, 18(3): 532-538.  DOI: 10.1016/S2095-3119(18)61935-5
    Abstract ( )   PDF (333KB) ( )  
    We identified a wheat (Triticum aestivum L.) multi-pistil mutant from an F2 breeding population in 2012, named 12TP (three pistils in one floret).  Genetic analysis showed that one dominant gene locus controlled the multi-pistil trait.  Using homozygous normal and multi-pistil lines (near-isogenic lines; NILs) derived from the original mutant 12TP, a simple sequence repeat (SSR) marker assay located the 12TP locus on chromosome arm 2DL.  Four SSR markers were linked to 12TP and their order was Xcfd233→Xcfd62-12TP→Xwmc41→Xcfd168 at 15.85, 10.47, 2.89, and 10.37 cM, respectively.  The average genetic expressivity of the trait ‘three pistils in one floret’ was more than 98% in seven homozygous 12TP lines; however, the average genetic expressivity in heterozygous F1 plants was about 49%.  Thus, the 12TP is a semi-dominant gene locus, which differ from all previously reported multi-pistil mutants.  Mutant 12TP is a new useful germplasm for study of wheat floral development and for breeding of high yield wheat. 
    Patent analysis provides insights into the history of cotton molecular breeding worldwide over the last 50 years
    HE Wei, ZHAO Hui-min, YANG Xiao-wei, ZHANG Rui, WANG Jing-jing
    2019, 18(3): 539-552.  DOI: 10.1016/S2095-3119(18)62012-X
    Abstract ( )   PDF (1488KB) ( )  
    Cotton is a globally important natural fiber and oilseed crop of crucial economic significance.  Molecular breeding has become a dominant method of cotton cultivation because it allows for a shorter breeding period and directional selection of high quality genes.  Patent data are key resources and are the core competitiveness of agricultural development, as the world’s largest and most reliable source of technical information.  However, little attention has been paid to patent analysis of cotton molecular breeding.  This study uses bibliometric analysis methodology and technical classification indexing to reveal global development trends of cotton molecular breeding, based on patents by retrieval methods and expert screening.  The annual number of patents, the life-cycle of patent-based technology, patent portfolios of primary countries, and main patentees, as well as technical distribution of patents, were analyzed in this study.  In addition, this study put emphasis on the comparative analysis of two important patentees through patent roadmaps based on the relationship among patent citations.  Finally, in order to understand the trend of new molecular breeding technology, patents related to clustered regularly interspaced short palindromic repeats (CRISPR), RNA interference (RNAi), and gene chip were also analyzed, all of which apply to cotton but also to other crops.  Results in this paper can provide references for cotton molecular breeding researchers and relevant management departments.
    GmNMH7, a MADS-box transcription factor, inhibits root development and nodulation of soybean (Glycine max [L.] Merr.)
    MA Wen-ya, LIU Wei, HOU Wen-sheng, SUN Shi, JIANG Bing-jun, HAN Tian-fu, FENG Yong-jun, WU Cun-xiang
    2019, 18(3): 553-562.  DOI: 10.1016/S2095-3119(18)61992-6
    Abstract ( )   PDF (1031KB) ( )  
    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.
    Continuous applications of biochar to rice: Effects on grain yield and yield attributes
    HUANG Min, FAN Long, JIANG Li-geng, YANG Shu-ying, ZOU Ying-bin, Norman Uphoff
    2019, 18(3): 563-570.  DOI: 10.1016/S2095-3119(18)61993-8
    Abstract ( )   PDF (265KB) ( )  
    Biochar is considered as a beneficial soil amendment for crop production.  However, limited information is available on the effects of continuous applications of biochar on rice.  In this study, a fixed field experiment was conducted in the early and late rice-growing seasons from 2015 to 2017.  Grain yield and yield attributes with a widely-grown rice cultivar Zhongzao 39
    were compared, with and without applications of biochar in each season.  The results showed that grain yield initially decreased with biochar applications in the first three seasons due to decreases in grain weight and harvest index.  Although there were further relative decreases in grain weight and harvest index for rice that was supplied with biochar in the fourth to sixth seasons, grain yield was increased (by 4–10%) because of increases in sink size (spikelets per m2) and total biomass.  The increased sink size in rice whose soil had been supplied with biochar in the fourth to sixth seasons was achieved by increasing panicle size (spikelets per panicle) or number of panicles, or both.  Our study suggests that the positive effects of biochar application on rice yield and yield attributes depend on the duration of biochar application.  Further investigations are needed to determine what are the soil and physiological processes for producing yield responses associated with ongoing applications of biochar.  Also, it should be evaluated the performance of biochar application combined with other management practices, especially those can increase the grain weight and harvest index in rice production.
    Estimates on nitrogen uptake in the subsequent wheat by above-ground and root residue and rhizodeposition of using peanut labeled with 15N isotope on the North China Plain
    ZHANG Kai, ZHAO Jie, WANG Xi-quan, XU He-shui, ZANG Hua-dong, LIU Jing-na, HU Yue-gao, ZENG Zhao-hai
    2019, 18(3): 571-579.  DOI: 10.1016/S2095-3119(18)62112-4
    Abstract ( )   PDF (449KB) ( )  
    Leguminous crops play a vital role in enhancing crop yield and improving soil fertility.  Therefore, it can be used as an organic N source for improving soil fertility.  The purpose of this study was to (i) quantify the amounts of N derived from rhizodeposition, root and above-ground biomass of peanut residue in comparison with wheat and (ii) estimate the effect of the residual N on the wheat-growing season in the subsequent year.  The plants of peanut and wheat were stem fed with 15N urea using the cotton-wick method at the Wuqiao Station of China Agricultural University in 2014.  The experiment consisted of four residue-returning strategies in a randomized complete-block design: (i) no return of crop residue (CR0); (ii) return of above-ground biomass of peanut crop (CR1); (iii) return of peanut root biomass (CR2); and (iv) return of all residue of the whole peanut plant (CR3).  The 31.5 and 21% of the labeled 15N isotope were accumulated in the above-ground tissues (leaves and stems) of peanuts and wheat, respectively.  N rhizodeposition of peanuts and wheat accounted for 14.91 and 3.61% of the BG15N, respectively.  The 15N from the below-ground 15N -labeled of peanuts were supplied 11.3, 5.9, 13.5, and 6.1% of in the CR0, CR1, CR2, and CR3 treatments, respectively.  Peanut straw contributes a significant proportion of N to the soil through the decomposition of plant residues and N rhizodeposition.  With the current production level on the NCP, it is estimated that peanut straw can potentially replace 104 500 tons of synthetic N fertilizer per year.  The inclusion of peanut in rotation with cereal can significantly reduce the use of N fertilizer and enhance the system sustainability.

    Identification of commercial cultivars of Agaricus bisporus in China using genome-wide microsatellite markers
    WANG Li-ning, GAO Wei, WANG Qiong-ying, QU Ji-bin, ZHANG Jin-xia, HUANG Chen-yang
    2019, 18(3): 580-589.  DOI: 10.1016/S2095-3119(18)62126-4
    Abstract ( )   PDF (1927KB) ( )  
    Agaricus bisporus is one of the most widely cultivated mushrooms in the world. Commercial cultivars are usually phenotypically alike and easy to be copied by isolating tissue cultures. This brings great challenges to distinguish different cultivars and to protect new varieties. Thus, techniques for the accurate identification of cultivars are essentially required. In this study, we accurately identified 11 commercial cultivars of A. bisporus released in China by using microsatellite (SSR, simple sequence repeat) markers. SSR markers were developed by mining the genome sequence. A total of 3 134 SSRs were identified, of which 1 490 SSRs were distributed in gene models, and 1 644 in the intergenic regions. A total of 17 polymorphic primer pairs were developed and SSR fingerprints were constructed for all the commercial cultivars. These SSR markers generated a total of 73 alleles, with an average of 4.29 per locus. Specifically, the primer combination of AB_SSR_2341 and AB_SSR_2590 could distinguish all the 11 commercial cultivars. The similarity coefficients of the 11 commercial cultivars were between 0.56 and 0.95 indicating that some of them were close related. Our results provide an efficient technique for the identification of A. bisporus cultivars in China, which can also facilitate the marker-assisted breeding in the future.
    Supplemental blue and red light promote lycopene synthesis in tomato fruits
    XIE Bao-xing, WEI Jing-jing, ZHANG Yi-ting, SONG Shi-wei, SU Wei, SUN Guang-wen, HAO Yanwei, LIU Hou-cheng
    2019, 18(3): 590-598.  DOI: 10.1016/S2095-3119(18)62062-3
    Abstract ( )   PDF (440KB) ( )  
    Lycopene, one of the strongest natural antioxidants known and the main carotene in ripe tomato, is very important for human health.  Light is well known to be one of the most important environmental stimuli influencing lycopene biosynthesis; specifically, red light induces higher lycopene content in tomato.  However, whether blue light promotes lycopene synthesis remains elusive and exactly how light stimulation promotes lycopene synthesis remains unclear.  We applied supplemental blue and red lighting on tomato plants at anthesis to monitor the effect of supplemental blue and red lighting on lycopene synthesis.  Our results showed that supplemental blue/red lighting induced higher lycopene content in tomato fruits; furthermore, we found that the expression of key genes in the lycopene synthesis pathway was induced by supplemented blue/red light.  The expression of light signaling components, such as red-light receptor phytochromes (PHYs), blue-light receptor cryptochromes (CRYs) and light interaction factors, phytochrome-interacting factors (PIFs) and ELONGATED HYPOCOTYL 5 (HY5) were up- or down-regulated by blue/red lighting.  Thus, blue and red light increased lycopene content in tomatoes by inducing light receptors that modulate HY5 and PIFs activation to mediate phytoene synthase 1 (PSY1) gene expression.  These results provide a sound theoretical basis for further elucidation of the light regulating mechanism of lycopene synthesis in tomatoes, and for instituting a new generation of technological innovations for the enhancement of lycopene accumulation in crop production.
    Plant Protection
    Soil application of Trichoderma asperellum GDFS1009 granules promotes growth and resistance to Fusarium graminearum in maize
    HE An-le, LIU Jia, WANG Xin-hua, ZHANG Quan-guo, SONG Wei, CHEN Jie
    2019, 18(3): 599-607.  DOI: 10.1016/S2095-3119(18)62089-1
    Abstract ( )   PDF (945KB) ( )  
    Of diseases affecting maize (Zea mays), Fusarium graminearum is one of the most common pathogenic fungi that cause stalk rot.  In the present study, the Trichoderma asperellum GDFS1009 strain was shown to be an effective biocontrol agent against stalk rot.  In a confrontation culture test, Trichoderma strain displayed an approximately 60% inhibition rate on the mycelial growth of F. graminearum.  In pot trials, the application of 2 g/pot of T. asperellum GDFS1009 granules had the best control effect on stalk rot at the seedling stage (up to 53.7%), while the average plant height and fresh weight were also significantly improved.  Additionally when fertilizer was added at 8 g/pot, the application of 3 g/pot of Trichoderma granules had the best control effect on maize stalk rot (40.95%).  In field trials, when inoculating F. graminearum alone, the disease index for inoculating was 62.45, but only 31.43 after treatment with T. asperellum GDFS1009 granules, suggesting a control efficiency of 49.67%.  Furthermore, in a naturally F. graminearum-infected field, Trichoderma granules, when applied for 3 consecutive years, showed significant control of stalk rot and increased yields.
    The effects of Trichoderma on preventing cucumber fusarium wilt and regulating cucumber physiology
    LI Mei, MA Guang-shu, LIAN Hua, SU Xiao-lin, TIAN Ying, HUANG Wen-kun, MEI Jie, JIANG Xi-liang
    2019, 18(3): 607-617.  DOI: 10.1016/S2095-3119(18)62057-X
    Abstract ( )   PDF (416KB) ( )  
    In our previous studies, we identified 3 Trichoderma strains with anti-Fusarium oxysporum activity, including T. asperellum 525, T. harzianum 610, and T. pseudokoningii 886.  Here, we evaluated the effects of these 3 Trichoderma strains on preventing cucumber fusarium wilt through pot culture and greenhouse culture experiments.  All 3 Trichoderma strains demonstrated higher control effects toward cucumber fusarium wilt than previous studies, with efficacies over 78%.  Additionally, inoculation with the 3 Trichoderma strains significantly promoted the quality and yield of cucumbers.  Among the 3 strains, Trichoderma 866 was the most effective, with disease control efficacy of 78.64% and a cucumber yield increase of 33%.  Furthermore, seedlings inoculated with Trichoderma exhibited significantly increased measures of plant height, stem diameter, leaf area, aboveground fresh weight, underground fresh weight, chlorophyll content, and nitric nitrogen content, as well as the activities of several stress-resistance enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO), and ascorbate oxidase (AAO).  In addition, the plants inoculated with Trichoderma showed decreased cell membrane permeability and malondialdehyde (MDA) content in the leaves.  Together, our results suggest that T. asperellum 525, T. harzianum 610, and T. pseudokoningii 886 inoculations inhibit F. oxysporum infection, stimulate the metabolism in cucumbers, and enhance the activities of stress-resistance enzymes, which consequently promote the growth of cucumber plants, prevent cucumber fusarium wilt, and improve the yield and quality of cucumbers.  T. harzianum is a commonly used biocontrol fungus, while few studies have focused on T. asperellum or T. koningense.  In this study, strains of T. asperellum and T. pseudokoningii showed excellent plant disease prevention and growth promoting effects on cucumber, indicating that they also have great potential as biocontrol fungi.
    Pectate lyase is a factor in the adaptability for Heterodera glycines infecting tobacco
    TIAN Zhong-ling, SHI Hong-li, Munawar Maria, ZHENG Jing-wu
    2019, 18(3): 618-626.  DOI: 10.1016/S2095-3119(18)62090-8
    Abstract ( )   PDF (1094KB) ( )  
    The soybean cyst nematode, Heterodeara glycines, is a serious pathogen of soybean, and reported to be the host of a wide range of Fabaceae.  In the present study, the host specificity and reproductivity of two populations of H. glycines collected from soybean and tobacco were identified and characterized.  The comparative identity between β-1,4-endoglucanase, pectate lyase and chorismate mutase of H. glycines parasitizing on soybean and tobacco were 99, 97 and 98%, respectively.  The qRT-PCR analysis indicated that the expression of pectate lyase 2 gene was significantly higher in second-stage juveniles of H. glycines Henan population parasitizing on tobacco than that of H. glycines Shanxi population parasitizing on soybean.  In addition, the pectic acid content of cell wall was significantly higher (45%) in the roots of tobacco than the roots of soybean.  Our results indicate that the changes in transcript parasitism genes may be a result of long-term evolution illustrating how a plant-parasitic nematode adapts to the host environment for optimal infestation and survival.
    Polycalin isinvolved in the action mechanism of Cry2Aa toxin in Helicoverpa armigera (Hübner)
    WANG Bing-jie, WANG Ya-nan, WEI Ji-zhen, LIU Chen, CHEN Lin, Myint Myint Khaing, LIANG Ge-mei
    2019, 18(3): 627-635.  DOI: 10.1016/S1671-2927(00)12174
    Abstract ( )   PDF (392KB) ( )  
    Microsatellites reveal strong genetic structure in the common cutworm, Spodoptera litura
    WU Huai-heng, WAN Peng, HUANG Min-song, LEI Chao-liang
    2019, 18(3): 636-643.  DOI: 10.1016/S2095-3119(18)61989-6
    Abstract ( )   PDF (285KB) ( )  
    The common cutworm, Spodoptera litura (Lepidoptera: Noctuidae), is a voracious agricultural pest.  To increase understanding of the migration patterns and genetic diversity of different geographic populations of this species, we analyzed genetic variation in nine microsatellite loci among 576 individuals collected from 17 locations in China and one in Myanmar during 2011–2012.  We successfully identified 162 alleles, with an average of 18 alleles per locus and a range of 5 to 34.  The mean observed heterozygosity of the 18 populations ranged from 0.18 to 0.98, and the expected heterozygosity ranged from 0.19 to 0.89.  For the nine microsatellite markers studied, polymorphism information content ranged from 0.18 to 0.88 (mean=0.64).  We found low genetic differentiation among the 18 populations (mean F-statistics (FST)=0.05) and high genetic diversity among individuals.  Principle coordinates analysis indicated no significant correlation between geographic and genetic distance (r=0.04).  The value of  Nm (Nm>4)  estimated using coalescent-based methods suggests strong gene flow with migration.  The nine microsatellite markers identified in this study will be beneficial for further investigation of migration patterns and genetic diversity in S. litura.
    Transcriptional profile of gene clusters involved in the methylerythritol phosphate pathway in Bacillus subtilis 916
    XIAO Ya-jing, GAO Tan-tan, PENG Qi, ZHANG Jie, SUN Dong-mei, SONG Fu-ping
    2019, 18(3): 644-655.  DOI: 10.1016/S2095-3119(18)62001-5
    Abstract ( )   PDF (680KB) ( )  
    The methylerythritol phosphate pathway is responsible for the biosynthesis of terpenoids, the largest class of secondary metabolites.  Although the structures and functions of the proteins involved in this pathway have been well studied in Bacillus subtilis, only a few studies have reported the transcriptional profile of the genes involved.  Therefore, we analyzed methylerythritol phosphate pathway genes in the genome of B. subtilis 916, which has been developed as a biological control agent against some rice diseases in China.  Our results showed that methylerythritol phosphate pathway genes were distributed throughout the genome of this strain.  These genes were transcribed during both the exponential and stationary phases.  We further confirmed the transcription units of dxs, dxr, ispD, ispF, ipK, ispG, ispH, idi, and ispA in B. subtilis 916 through reverse transcription-PCR analyses; the results showed that these nine genes were located in seven different operons.  The transcript start sites of the seven different operons were determined by 5´-rapid amplification of cDNA ends-PCR.  Thus, our study provides a molecular basis at the transcriptional level for investigating homoterpene synthesis in the methylerythritol phosphate pathway of B. subtilis 916.
    Agro-ecosystem & Environment
    Effects of urea enhanced with different weathered coal-derived humic acid components on maize yield and fate of fertilizer nitrogen
    ZHANG Shui-qin, YUAN Liang, LI Wei, LIN Zhi-an, LI Yan-ting, HU Shu-wen, ZHAO Bing-qiang
    2019, 18(3): 656-666.  DOI: 10.1016/S2095-3119(18)61950-1
    Abstract ( )   PDF (773KB) ( )  
    Humic acid (HA) is a readily available and low-cost material that is used to enhance crop production and reduce nitrogen (N) loss.  However, there is little consensus on the efficacy of different HA components.  In the current study, a soil column experiment was conducted using the 15N tracer technique in Dezhou City, Shandong Province, China, to compare the effects of urea with and without the addition of weathered coal-derived HA components on maize yield and the fate of fertilizer-derived N (fertilizer N).  The HA components were incorporated into urea by blending different HA components into molten urea to obtain the three different types of HA-enhanced urea (HAU).  At harvest, the aboveground dry biomass of plants grown with HAU was enhanced by 11.50–21.33% when compared to that of plants grown with U.  More significantly, the grain yields under the HAU treatments were 5.58–18.67% higher than the yield under the urea treatment.  These higher yields were due to an increase in the number of kernels per plant rather than the weight of individual kernels.  The uptake of fertilizer N under the HAU treatments was also higher than that under the urea treatment by 11.49–29.46%, while the unaccounted N loss decreased by 12.37–30.05%.  More fertilizer-derived N was retained in the 0–30 cm soil layer under the HAU treatments than that under the urea treatment, while less N was retained in the 30–90 cm soil layer.  The total residual amount of fertilizer N in the soil column, however, did not differ significantly between the treatments.  Of the three HAU treatments investigated, the one with an HA fraction derived from extraction with pH values ranging from 6 to 7, resulted in the best improvement in all assessment targets.  This is likely due to the abundance of the COO/C–N=O group in this HA component.
    Response of soil Olsen-P to P budget under different long-term fertilization treatments in a fluvo-aquic soil
    ZHANG Wei-wei, ZHAN Xiao-ying, ZHANG Shu-xiang, Khalid Hamdan Mohamed Ibrahima, XU Ming-gang
    2019, 18(3): 667-676.  DOI: 10.1016/S2095-3119(18)62070-2
    Abstract ( )   PDF (387KB) ( )  

    The concentration of soil Olsen-P is rapidly increasing in many parts of China, where P budget (P input minus P output) is the main factor influencing soil Olsen-P.  Understanding the relationship between soil Olsen-P and P budget is useful in estimating soil Olsen-P content and conducting P management strategies.  To address this, a long-term experiment (1991–2011) was performed on a fluvo-aquic soil in Beijing, China, where seven fertilization treatments were used to study the response of soil Olsen-P to P budget.  The results showed that the relationship between the decrease in soil Olsen-P and P deficit could be simulated by a simple linear model.  In treatments without P fertilization (CK, N, and NK), soil Olsen-P decreased by 2.4, 1.9, and 1.4 mg kg–1 for every 100 kg ha–1 of P deficit, respectively.  Under conditions of P addition, the relationship between the increase in soil Olsen-P and P surplus could be divided into two stages.  When P surplus was lower than the range of 729–884 kg ha–1, soil Olsen-P fluctuated over the course of the experimental period with chemical fertilizers (NP and NPK), and increased by 5.0 and 2.0 mg kg–1, respectively, when treated with chemical fertilizers combined with manure (NPKM and 1.5NPKM) for every 100 kg ha–1 of P surplus.  When P surplus was higher than the range of 729–884 kg ha–1, soil Olsen-P increased by 49.0 and 37.0 mg kg–1 in NPKM and 1.5NPKM treatments, respectively, for every 100 kg ha–1 P surplus.  The relationship between the increase in soil Olsen-P and P surplus could be simulated by two-segment linear models.  The cumulative P budget at the turning point was defined as the “storage threshold” of a fluvo-aquic soil in Beijing, and the storage thresholds under NPKM and 1.5NPKM were 729 and 884 kg ha–1 P for more adsorption sites.  According to the critical soil P values (CPVs) and the relationship between soil Olsen-P and P budget, the quantity of P fertilizers for winter wheat could be increased and that of summer maize could be decreased based on the results of treatments in chemical fertilization.  Additionally, when chemical fertilizers are combined with manures (NPKM and 1.5NPKM), it could take approximately 9–11 years for soil Olsen-P to decrease to the critical soil P values of crops grown in the absence of P fertilizer. 

    Changes in fungal community and diversity in strawberry rhizosphere soil after 12 years in the greenhouse
    LI Wei-hua, LIU Qi-zhi
    2019, 18(3): 677-687.  DOI: 10.1016/S2095-3119(18)62003-9
    Abstract ( )   PDF (829KB) ( )  
    Soil fungi play a very important role in the soil ecological environment.  In agricultural production, long-term monoculture and continuous cropping lead to changes in fungal community diversity.  However, the effects of long-term monoculture and continuous cropping on strawberry plant health and fungal community diversity have not been elucidated.  In this study, using high-throughput sequencing (HTS), we compared the fungal community and diversity of strawberry rhizosphere soil after various durations of continuous cropping (0, 2, 4, 6, 8, 10 and 12 years).  The results showed that soil fungal diversity increased with consecutive cropping years.  Specifically, the soil-borne disease pathogens Fusarium and Guehomyces were significantly increased after strawberry continuous cropping, and the abundance of nematicidal (Arthrobotrys) fungi decreased from the fourth year of continuous cropping.  The results of correlation analysis suggest that these three genera might be key fungi that contribute to the changes in soil properties that occur during continuous cropping.  In addition, physicochemical property analysis showed that the soil nutrient content began to decline after the fourth year of continuous cropping.  Spearman’s correlation analysis showed that soil pH, available potassium (AK) and ammonium nitrogen (NH4+-N) were the most important edaphic factors leading to contrasting beneficial and pathogenic associations across consecutive strawberry cropping systems.  
    Reduction in cadmium accumulation in japonica rice grains by CRISPR/Cas9-mediated editing of OsNRAMP5
    YANG Chang-hong, ZHANG Yang, HUANG Chao-feng
    2019, 18(3): 688-697.  DOI: 10.1016/S2095-3119(18)61904-5
    Abstract ( )   PDF (625KB) ( )  
    Cadmium (Cd) intake is harmful to human health and Cd contamination in rice grains represents a severe threat to those consuming rice as a staple food.  Knockout of Cd transporters is a promising strategy to reduce Cd accumulation in rice grains.  OsNRAMP5 is the major transporter for Cd and manganese (Mn) uptake in rice.  Nevertheless, it is uncertain whether knockout of OsNRAMP5 is applicable to produce low Cd rice without affecting plant growth and grain yield.  In this study, we adopted CRISPR/Cas9-based gene editing technology to knock out OsNRAMP5 in two japonica varieties.  We generated three independent transgene-free osnramp5 mutants and investigated the effect of osnramp5 mutations on Cd accumulation and plant growth.  Hydroponic experiments showed that plant growth and chlorophyll content were significantly reduced in osnramp5 mutants at low Mn conditions, and this defective growth in the mutants could be fully rescued by supply of high levels of Mn.  Cd and Mn accumulation in both roots and shoots was markedly reduced in the mutants compared to that in wild-type plants.  In paddy field experiments, although Cd in flag leaves and grains was greatly reduced in osnramp5 mutants, some agronomic traits including plant height, seed setting rate, and grain number per panicle were affected in the mutants, which ultimately caused a mild reduction in grain yield.  The reduced plant growth in the mutants can be attributed to a marked decrease in Mn accumulation.  Our results reveal that the manipulation of OsNRAMP5 should be treated with caution: When assessing the applicability of osnramp5 mutants, soil pH and soil water content in paddy fields need to be taken into consideration, since they might affect the levels of available Mn in the soil and consequently determine the effect of the mutation on grain yield.
    Short Communication
    Molecular characterization of Apple necrotic mosaic virus identified in crabapple (Malus spp.) tree of China
    HU Guo-jun, DONG Ya-feng, ZHANG Zun-ping, FAN Xu-dong, REN Fang
    2019, 18(3): 698-704.  DOI: 10.1016/S2095-3119(18)62116-1
    Abstract ( )   PDF (363KB) ( )  
    Apple necrotic mosaic virus (ApNMV) was identified in crabapple trees with mosaic symptoms from Zaozhuang, Shandong Province, China, by reverse transcription polymerase chain reaction (RT-PCR) analysis.  The complete nucleotide sequences of one isolate from crabapple (ApNMV-Hai) and two isolates from apple (ApNMV-Hua and -Qu) were determined.  The sizes of genomic RNA1, 2 and 3 of the three isolates differed from those of the previously reported isolate ApNMV-P126 from Japanese apple, especially RNA3.  Compared with the nucleotide (nt) sequence of RNA3 in isolate P126, those in the Hai and Qu isolates were 7 and 33 nt shorter, respectively, and that of isolate Hua was 7 nt longer.  Alignment analyses showed that these differences in size were mainly due to differences in the lengths of the 5´ untranslated region (UTR) and the UTR region between the ORFs encoding the movement protein and the coat protein.  In the phylogenetic trees constructed using the full genomic sequences of RNA1, 2 and 3, the isolate Hai clustered into a group with the isolate Qu in the RNA1 tree, but formed an individual branch in the RNA2 and 3 trees.  Three recombination events were identified in the nucleotide sequences of RNA1 and 2 among the isolates ApNMV-Hai, -Hua, and -Qu.  This is the first report of the full genome sequence of ApNMV in crabapple.