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Identification and epitope mapping of anti-p72 single-chain antibody against African swine fever virus based on phage display antibody library

SONG Jin-xing, WANG Meng-xiang, ZHANG Yi-xuan, WAN Bo, DU Yong-kun, ZHUANG Guo-qing, LI Zi-bin, QIAO Song-lin, GENG Rui, WU Ya-nan, ZHANG Gai-ping

2023, 22 (9): 2834-2847. DOI: 10.1016/j.jia.2023.07.039

Abstract （194） PDF in ScienceDirect

African swine fever virus (ASFV) is a lethal pathogen that causes severe threats to the global swine industry and it has already had catastrophic socio-economic effects. To date, no licensed prophylactic vaccine exists. Limited knowledge exists about the major immunogens of ASFV and the epitope mapping of the key antigens. As such, there is a considerable requirement to understand the functional monoclonal antibodies (mAbs) and the epitope mapping may be of utmost importance in our understanding of immune responses and designing improved vaccines, therapeutics, and diagnostics. In this study, we generated an ASFV antibody phage-display library from ASFV convalescent swine PBMCs, further screened a specific ASFV major capsid protein (p72) single-chain antibody and fused with an IgG Fc fragment (scFv-83-Fc), which is a specific recognition antibody against ASFV Pig/HLJ/2018 strain. Using the scFv-83-Fc mAb, we selected a conserved epitope peptide (²²¹MTGYKH²²⁶) of p72 retrieved from a phage-displayed random peptide library. Moreover, flow cytometry and cell uptake experiments demonstrated that the epitope peptide can significantly promote BMDCs maturation in vitro and could be effectively uptaken by DCs, which indicated its potential application in vaccine and diagnostic reagent development. Overall, this study provided a valuable platform for identifying targets for ASFV vaccine development, as well as to facilitate the optimization design of subunit vaccine and diagnostic reagents

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Population genetic variation and historical dynamics of the natural enemy insect Propylea japonica (Coleoptera: Coccinellidae) in China

WANG Meng-qi, ZHANG Hong-rui, XI Yu-qiang, WANG Gao-ping, ZHAO Man, ZHANG Li-juan, GUO Xian-ru

2023, 22 (8): 2456-2469. DOI: 10.1016/j.jia.2022.08.025

Abstract （349） PDF in ScienceDirect

Propylea japonica (Coleoptera: Coccinellidae) is a natural enemy insect with a wide range of predation in Chinese mainland and is commonly used in pest management. However, its genetic pattern (i.e., genetic variation, genetic structure, and historical population dynamics) is still unclear, impeding the development of biological control of insect pests. Population genetic research has the potential to optimize strategies at different stages of the biological control processes. This study used 23 nuclear microsatellite sites and mitochondrial COI genes to investigate the population genetics of Propylea japonica based on 462 specimens collected from 30 sampling sites in China. The microsatellite dataset showed a moderate level of genetic diversity, but the mitochondrial genes showed a high level of genetic diversity. Populations from the Yellow River basin were more genetically diverse than those in the Yangtze River basin. Propylea japonica has not yet formed a significant genealogical structure in China, but there was a population structure signal to some extent, which may be caused by frequent gene flow between populations. The species has experienced population expansion after a bottleneck, potentially thanks to the tri-trophic plant–insect–natural enemy relationship. Knowledge of population genetics is of importance in using predators to control pests. Our study complements existing knowledge of an important natural predator in agroecosystems through estimating its genetic diversity and population differentiation and speculating about historical dynamics.

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Phosphorylation of SiRAV1 at Ser31 regulates the SiCAT expression to enhance salt tolerance in Setaria italica

LI Qiao-lu, LI Zhi-yong, WANG Meng-meng, YAN Jing-wei, FANG Lin

2023, 22 (12): 3638-3651. DOI: 10.1016/j.jia.2023.04.034

Abstract （178） PDF in ScienceDirect

Salinity severely affects plant growth and development. Thus, it is crucial to identify the genes functioning in salt stress response and unravel the mechanism by which plants against salt stress. This study used the phosphoproteomic assay and found that 123 of the 4 000 quantitative analyzed phosphopeptides were induced by salt stress. The functional annotation of the non-redundant protein database (NR) showed 23 differentially expressed transcription factors, including a phosphopeptide covering the Serine 31 in the RAV (related to ABI3/VP1) transcription factor (named SiRAV1). SiRAV1 was located in the nucleus. Phenotypic and physiological analysis showed that overexpressing SiRAV1 in foxtail millet enhanced salt tolerance and alleviated the salt-induced increases of H₂O₂ accumulation, malondialdehyde (MDA) content, and percent of electrolyte leakage. Further analysis showed that SiRAV1 positively regulated SiCAT expression to modulate the catalase (CAT) activity by directly binding to the SiCAT promoter in vivo and in vitro. Moreover, we found that phosphorylation of SiRAV1 at the Ser31 site positively regulated salt tolerance in foxtail millet via enhancing its binding ability to SiCAT promoter but did not affect its subcellular localization. Overall, our results define a mechanism for SiRAV1 function in salt response where salt-triggered phosphorylation of SiRAV1 at Ser31 enhances its binding ability to SiCAT promoter, and the increased SiCAT expression contributes to salt tolerance in foxtail millet.

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Transcriptome analysis for understanding the mechanism of dark septate endophyte S16 in promoting the growth and nitrate uptake of sweet cherry

WU Fan-lin, QU De-hui, TIAN Wei, WANG Meng-yun, CHEN Fei-yan, LI Ke-ke, SUN Ya-dong, SU Ying-hua, YANG Li-na, SU Hong-yan, WANG Lei

2021, 20 (7): 1819-1831. DOI: 10.1016/S2095-3119(20)63355-X

Abstract （169） PDF in ScienceDirect

Sweet cherry is one of the most popular fresh fruits in the world. Previously, we isolated a soilborne dark septate endophyte (DSE) strain, S16, which promoted the growth of Gisela 5 sweet cherry rootstock. However, little is known about the molecular mechanism of the effect of S16 on the growth of sweet cherry. In this study, the physiological parameters and transcript profiles of sweet cherry roots were analyzed under S16 treatment compared with a control to elucidate the molecular mechanisms of the effect of this strain on sweet cherry growth. After inoculation with S16, sweet cherry seedlings exhibited more vigorous growth. Moreover, we identified 4 249 differentially expressed genes (DEGs) between S16-treated plants and the control. Many of the DEGs are involved in pathways related to plant growth, such as cellular metabolic and plant hormone pathways. Additionally, some genes involved in nitrate regulation were also enriched; and these genes may be involved in the regulation of nitrate uptake in plants. Physiological index detection demonstrated that S16 could improve the nitrate assimilation of sweet cherry via NO₃^– transporters. This RNA-seq dataset provides comprehensive insight into the transcriptomic landscape to reveal the molecular mechanisms whereby the DSE influences the growth of sweet cherry.

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Calibration and validation of SiBcrop Model for simulating LAI and surface heat fluxes of winter wheat in the North China Plain

CHEN Ying, LIU Feng-shan, TAO Fu-lu, GE Quan-sheng, JIANG Min, WANG Meng, ZHAO Feng-hua

2020, 19 (9): 2206-2215. DOI: 10.1016/S2095-3119(20)63178-1

Abstract （127） PDF in ScienceDirect

The accurate representation of surface characteristic is an important process to simulate surface energy and water flux in land-atmosphere boundary layer. Coupling crop growth model in land surface model is an important method to accurately express the surface characteristics and biophysical processes in farmland. However, the previous work mainly focused on crops in single cropping system, less work was done in multiple cropping systems. This article described how to modify the sub-model in the SiBcrop to realize the accuracy simulation of leaf area index (LAI), latent heat flux (LHF) and sensible heat flux (SHF) of winter wheat growing in double cropping system in the North China Plain (NCP). The seeding date of winter wheat was firstly reset according to the actual growing environment in the NCP. The phenophases, LAI and heat fluxes in 2004–2006 at Yucheng Station, Shandong Province, China were used to calibrate the model. The validations of LHF and SHF were based on the measurements at Yucheng Station in 2007–2010 and at Guantao Station, Hebei Province, China in 2009–2010. The results showed the significant accuracy of the calibrated model in simulating these variables, with which the R2, root mean square error (RMSE) and index of agreement (IOA) between simulated and observed variables were obviously improved than the original code. The sensitivities of the above variables to seeding date were also displayed to further explain the simulation error of the SiBcrop Model. Overall, the research results indicated the modified SiBcrop Model can be applied to simulate the growth and flux process of winter wheat growing in double cropping system in the NCP.

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Exploiting push-pull strategy to combat the tea green leafhopper based on volatiles of Lavandula angustifolia and Flemingia macrophylla

HAN Shan-jie, WANG Meng-xin, WANG Yan-su, WANG Yun-gang, CUI Lin, HAN Bao-yu

2020, 19 (1): 193-203. DOI: 10.1016/S2095-3119(19)62778-4

Abstract （181） PDF in ScienceDirect

Thirteen volatile compounds were identified from Flemingia macrophylla plants. Eight major components significantly attracted the tea green leafhoppers, Empoasca flavescens F. Based on their relative abundances, following synthetic blends were made for field experiments: 1) eight-component-attractant blend included Z-3-hexen-1-ol, Z-3-hexenyl acetate, Z-ocimene, MeSA, Z-3-hexenyl butyrate, dodecane, hexadecane and nonanal at 10, 10, 1, 11, 2, 6, 2 and 4 mg mL^–1 in n-hexane, respectively; 2) four-component-attractant blend #1 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and nonanal at 2, 10, 10 and 4 mg mL^–1 in n-hexane, respectively; 3) four-component-attractant blend #2 contained hexadecane, Z-3-hexenyl acetate, Z-3-hexen-1-ol and MeSA at 2, 10, 10 and 11 mg mL^–1 in n-hexane, respectively. Thymol and 1-methoxy-4-methyl-2-(1-methylethyl)-benzene, identified from Lavandula angustifolia aeration samples, significantly repelled the leafhopper as strong repellents when tested alone or in combination at 10 mg mL^–1. For field bioassays, each attractant lure was attached to a bud green sticky board hung from a bamboo stick at above tea plant level for catching the leafhoppers, whereas the repellent dispenser was tied to a tea branch inside tea clump for pushing the leafhoppers away from tea clumps. The results showed that the eight-component-attractant blend caught similar numbers of the leafhopper as did the four-component-attractant blend #1 at about 53–79 leafhoppers/trap/day, which were significantly higher than those on the hexane-control bud green sticky boards. Average leafhopper catches from un-baited sticky boards were about 51–73 leafhoppers/trap/day when pushed by the repellents placed inside tea plants, with the two-component-repellent blend being more effective than their single components. When the two-component-repellent blend was further tested with the three attractant blends in a push-pull fashion, average trap catches ranged from 62 to 92 leafhoppers/trap/day. Control efficacy on the leafhoppers within the push-pull zones increased progressively from day 1 (43%) to day 5 (73%). This push-pull approach might have a great potential as a green control strategy for combating the tea green leafhoppers.

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Combined application of Trichoderma harzianum SH2303 and difenoconazole-propiconazolein controlling Southern corn leaf blight disease caused by Cochliobolus heterostrophus in maize

WANG Shao-qing, MA Jia, WANG Meng, WANG Xin-hua, LI Ya-qian, CHEN Jie

2019, 18 (9): 2063-2071. DOI: 10.1016/S2095-3119(19)62603-1

Abstract （165） PDF in ScienceDirect

Southern corn leaf blight (SCLB) disease caused by Cochliobolus heterostrophus is one of the major threats to corn production worldwide. The synergistic application of low toxic chemical fungicide and biocontrol agents could improve biocontrol stability and efficiency against plant diseases, which ultimately reduce use of chemical fungicide. Trichoderma spp., well-known biocontrol fungi have been used to control some foliar diseases. However, few works have been reported on synergistic application of chemical fungicide and Trichoderma against foliar diseases. This study was aimed to investigate the control effect on the synergistic application of Trichoderma harzianum SH2303 and difenoconazole-propiconazole (DP) against SCLB. Results showed that the synergistic application of DP and SH2303 reduced the leaf spot area compared to the control. The efficacy of synergistic application of DP+SH2303 against SCLB could last for 15–20 d in pot trial under the greenhouse condition. Under the natural field condition, maize treated with DP+DP and DP+SH2303 showed 60% control, which was higher than that of SH2303+DP (45%) and SH2303+SH2303 (35%). All these treatments induced the synthesis of defense-related enzymes (phenylalanine ammonia lyase (PAL), catalase (CAT), and superoxide dismutase (SOD)) and the defence-related gene expression of SA pathway (PR1). Taken together the in-vitro leaf test and field trial, the control of SCLB by synergistic application of DP+SH2303 was similar to that of DP+DP. Among synergistic application, the sequential application of DP+SH2303 showed better control than the sequential application of SH2303+DP. It was concluded that the synergistic application of chemical fungicide (DP) and biocontrol agent (T. harzianum SH2303) could be used to reduce the chemical fungicide and to reduce the SCLB diseases in maize, which provided alternative approach to realize an eco-friendly controlling of the foliar disease.

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Overview on current criteria for heavy metals and its hint for the revision of soil environmental quality standards in China

CHEN Shi-bao, WANG Meng, LI Shan-shan, ZHAO Zhong-qiu, E Wen-di

2018, 17 (04): 765-774. DOI: 10.1016/S2095-3119(17)61892-6

Abstract （651） PDF in ScienceDirect

Following rapid social and economic development over the past several decades, soil pollution by heavy metals (HMs) has been both serious and widespread in China. The Soil Environmental Quality Standards (SEQSs) in China (GB 15618-1995) have been introduced to encourage and enforce sustainable soil HM management. However, in recent years, HM contents in soils have frequently been found to exceed their associated standard values, while the crops growing on them might still meet regulatory standards, and vice versa. There is thus growing awareness that GB 15618-1995 does not effectively regulate current soil HM pollution, as it has encountered bottlenecks, and disappointing outcomes caused by poor execution along with deficiencies and gaps in the policies. However, due to the deficiency of scientific research about relationships between soil HM concentrations and their ecological or human health effects, the development of SEQSs in China is still greatly restricted. This paper discusses international SEQSs of HMs as well their development in China over time, then examines current Chinese SEQSs to demonstrate their potential regulatory deficiencies by referring to international SEQSs. The corresponding legislative policies are described, and scientific information or responses are outlined for maintaining soil environmental quality. China’s experience has shown that policy and science can be linked to work in tandem to better understand and manage soil quality issues.

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MAPKs and acetyl-CoA are associated with Curvularia lunata pathogenicity and toxin production in maize

NI Xuan, GAO Jin-xin, YU Chuan-jin, WANG Meng, Sun Jia-nan, LI Ya-qian, CHEN Jie

2018, 17 (01): 139-148. DOI: 10.1016/S2095-3119(17)61697-6

Abstract （633） PDF in ScienceDirect

Mitogen-activated protein kinase (MAPK) cascades play an important role in extracellular signal transduction and are involved in the pathogenicity of fungal pathogens to host plants. In Curvularia lunata, the roles of two MAPK genes, Clk1 and Clm1, have already been studied. Clk1 is involved in conidia formation and pathogenicity, and Clm1 is closely related to pathogen cell wall formation and pathogenicity to maize leaves. In this study, a third C. lunata MAPK gene, Clh1, which is homologous to hog1, was successfully cloned. We found that a Clh1 deletion mutant had lower intracellular glycerol accumulation than the wild-type stain and was unable to grow normally under osmotic stress conditions. Furthermore, the deletion mutants of three C. lunata MAPK genes (Clk1, Clm1 and Clh1) had lower levels of acetyl-CoA, which is an important intermediate product in the synthesis of melanin and furan toxin, and down-regulated expression of pathogenicity-associated genes. Furthermore, pathogenicity and the ability to produce toxin were restored after adding acetyl-CoA to the culture medium, suggesting that acetyl-CoA is closely involved in the pathogen MAPK signaling pathway.

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Toxicity threshold of lead (Pb) to nitrifying microorganisms in soils determined by substrate-induced nitrification assay and prediction model

ZHENG Han, CHEN Li, LI Ning, LIU Bin, MENG Nan, WANG Meng, CHEN Shi-bao

2017, 16 (08): 1832-1840. DOI: 10.1016/S2095-3119(16)61586-1

Abstract （611） PDF in ScienceDirect

Lead (Pb) contamination has often been recorded in Chinese field soils. In recent years, efforts have been made to investigate Pb toxicity thresholds in soils with plant growth and microbial assays. However, the influence of soil properties on Pb toxicity impacts on soil microbial processes is poorly understood. In this study ten soils with different properties were collected in China to investigate the relationships between thresholds of Pb toxicity to soil microbes and soil properties. The effect of soil leaching on Pb toxicity was also investigated to determine the possible influence of added anions on Pb toxicity during dose-response tests. Toxicity was inferred by measuring substrate-induced nitrification in leached and non-leached soils after Pb addition. We found that soil microbe Pb toxicity thresholds (EC_x, x=10, 50) differed significantly between the soils; the 10% inhibition ratio values (EC₁₀) ranged from 86 to 218 mg kg^–1 in non-leached soils and from 101 to 313 mg kg^–1 in leached soils. The 50% inhibition ratio values (EC₅₀) ranged from 403 to 969 mg kg^–1 in non-leached soils and from 494 to 1 603 mg kg^–1 in leached soils. Soil leaching increased EC10 and EC50 values by an average leaching factor (LF) of 1.46 and 1.33, respectively. Stepwise multiple regression models predicting Pb toxicity to soil microbes were developed based on EC_x and soil properties. Based on these models, soil pH and organic carbon are the most important soil properties affecting Pb toxicity thresholds (R₂>0.60). The quantitative relationship between Pb toxicity and soil properties will be helpful for developing soil-specific guidance on Pb toxicity thresholds in Chinese field soils.

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Sod gene of Curvularia lunata is associated with the virulence in maize leaf

GAO Shi-gang, NI Xuan, LI Ying-ying, FU Ke-he, YU Chuan-jin, GAO Jin-xin, WANG Meng, LI Ya-qian, CHEN Jie

2017, 16 (04): 874-883. DOI: 10.1016/S2095-3119(16)61513-7

Abstract （976） PDF in ScienceDirect

Curvularia leaf spot, caused mainly by Curvularia lunata, is a widespread plant disease in China. In the recent years, directional host selection by the pathogen, which likely results in the virulence differentiation in pathogens, is widely reported. Among the hallmarks potentially associated to pathogen variation in virulence, superoxide dismutase gene Sod has been found to be closely related to the enhancement of virulence. In the present study, the full-length of Sod was obtained via Blastn alignment against GenBank and the whole genome of C. lunata. In order to understand the role of Sod in the virulence variation in C. lunata, targeted gene disruption was performed to construct Sod mutants. The cell wall degrading enzyme (CWDE) activities and toxin production of ΔSod were not distinctly different from wild-type strain CX-3 and its complon. However, at an early stage of infection, ΔSod virulence appeared to be lower than CX-3 and the complon, while at a later stage, its virulence gradually returned to the level of CX-3 and the complon. Furthermore, the melanin production of ΔSod was significantly reduced compared to CX-3 and the complon, suggesting that Sod gene influences the virulence by regulating melanin production at an early stage of infection but is not essential for pathogenicity. However, the disruption of Sod did not significantly affect the transcriptional expression of the melanin biosynthesis-associated genes, brn1 and scd. Therefore, we infer that Sod in C. lunata are involved, to some extent, with the virulence in maize leaf, but still needs further studies to have a clear understanding of its mechanism.

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The effects of the unsaturated degree of long-chain fatty acids on the rumen microbial protein content and the activities of transaminases and dehydrogenase in vitro

GAO Jian, JING Yu-jia, WANG Meng-zhi, SHI Liang-feng, LIU Shi-min

2016, 15 (2): 424-431. DOI: 10.1016/S2095-3119(15)61081-4

Abstract （1816） PDF in ScienceDirect

This study investigated the effects of the degree of unsaturation (unsaturity) of long-chain fatty acids on microbial protein content and the activities of transaminases and dehydrogenase in vitro using goat rumen fluid as the cultural medium. Six types of fatty acids, stearic acid (C18:0, group A, control group), oleic acid (C18:1, n-9, group B), linoleic acid (C18:2, n-6, group C), α-linolenic acid (C18:3, n-3, group D), arachidonic acid (C20:4, n-6, group E), and eicosapentaenoic acid (C20:5, n-3, group F), were tested, and the inclusion ratio of each fatty acid was 3% (w/w) in total of culture substrate. Samples were taken at 0, 3, 6, 9, 12, 18 and 24 h, respectively, during culture for analyses. Compared with stearic acid, linoleic acid, α-linolenic acid, and arachidonic acid increased the bacterial protein content, while oleic acid and eicosapentaenoic acid had no significant effects; the protozoal protein content was reduced for all the unsaturated fatty acids, and the magnitude of the reduction appeared to be associated with the degree of unsaturity of fatty acids. The total microbial protein content was dominantly accounted by the protozoal protein content (about 4–9 folds of the bacterial protein), and only increased by linoleic acid, but reduced by oleic acid, arachidonic acid and eicosapentaenoic acid. There were no significant effects in the activities of both glutamic oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) for all the other fatty acids, except for arachidonic acid which enhanced GOT activity and oleic acid which enhanced GPT activity. The total dehydrogenase activity was positively correlated with the degree of unsaturation of fatty acids. In conclusion, the inclusion of 3% of long-chain unsaturated fatty acids increased bacterial protein content, whereas reduced protozoal protein content and enhanced dehydrogenase activity. The fatty acids with more than three double bonds had detrimental effects on the microbial protein content. This work demonstrates for the first time the effect rule of the unsaturation degree of long-chain fatty acids on the rumen microbial protein in vitro.

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Impacts of the unsaturation degree of long-chain fatty acids on the volatile fatty acid profiles of rumen microbial fermentation in goats in vitro

GAO Jian, WANG Meng-zhi, JING Yu-jia, SUN Xue-zhao, WU Tian-yi, SHI Liang-feng

2016, 15 (12): 2827-2833. DOI: 10.1016/S2095-3119(16)61418-1

Abstract （874） PDF in ScienceDirect

This study investigated the impacts of the degree of unsaturation (unsaturity) of long-chain fatty acids on volatile fatty acid (VFA) profiles of rumen fermentation in vitro. Six types of long-chain fatty acids, including stearic acid (C18:0, control group), oleic acid (C18:1, n-9), linoleic acid (C18:2, n-6), α-linolenic acid (C18:3, n-3), arachidonic acid (C20:4, n-6) and eicosapentaenoic acid (C20:5, n-3), were tested. Rumen fluid from three goats fitted with ruminal fistulae was used as inoculum and the inclusion rate of long-chain fatty acid was at 3% (w/w) of substrate. Samples were taken for VFA analysis at 0, 3, 6, 9, 12, 18 and 24 h of incubation, respectively. The analysis showed that there were significant differences in the total VFA among treatments, sampling time points, and treatment×time point interactions (P<0.01). α-Linolenic acid had the highest total VFA (P<0.01) among different long-chain fatty acids tested. The molar proportion of acetate in total VFA significantly differed among treatments (P<0.01) and sampling time points (P<0.01), but not treatment×time point interactions (P>0.05). In contrast, the molar proportion of propionate did not differ among treatments during the whole incubation (P>0.05). However, for butyrate molar proportions, significant differences were found not only among sampling time points but also among treatments and treatment×time point interactions (P<0.01), with eicosapentaenoic acid having the highest value (P<0.01). Additionally, no statistically significant differences were found in the acetate to propionate ratios among treatments groups (P>0.05), even the treatments stearic acid and α-linolenic acid were numerically higher than the others. The inclusion of 3% long-chain unsaturated fatty acids differing in the degree of unsaturation brought out a significant quadratic regression relation between the total VFA concentration and the double bond number of fatty acid. In conclusion, the α-linolenic acid with 3 double bonds appeared better for improving rumen microbial fermentation and the total VFA concentration.

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Corn Yield Forecasting in Northeast China Using Remotely Sensed Spectral Indices and Crop Phenology Metrics

WANG Meng, TAO Fu-lu , SHI Wen-jiao

2014, 13 (7): 1538-1545. DOI: 10.1016/S2095-3119(14)60817-0

Abstract （1786） PDF in ScienceDirect

Early crop yield forecasting is important for food safety as well as large-scale food related planning. The phenology-adjusted spectral indices derived from Moderate Resolution Imaging Spectroradiometer (MODIS) data were used to develop liner regression models with the county-level corn yield data in Northeast China. We also compared the different spectral indices in predicting yield. The results showed that, using Enhanced Vegetation Index (EVI), Normalized Difference Water Index (NDWI) and Land Surface Water Index (LSWI), the best time to predict corn yields was 55-60 days after green-up date. LSWI showed the strongest correlation (R2=0.568), followed by EVI (R2=0.497) and NDWI (R2=0.495). The peak correlation between Wide Dynamic Range Vegetation Index (WDRVI) and yield was detected 85 days after green-up date (R2=0.506). The correlation was generally low for Normalized Difference Vegetation Index (NDVI) (R2=0.385) and no obvious peak correlation existed for NDVI. The coefficients of determination of the different spectral indices varied from year to year, which were greater in 2001 and 2004 than in other years. Leave-one-year-out approach was used to test the performance of the model. Normalized root mean square error (NRMSE) ranged from 7.3 to 16.9% for different spectral indices. Overall, our results showed that crop phenology-tuned spectral indices were feasible and helpful for regional corn yield forecasting.

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