Green Plant Protection Innovation: Challenges and Perspectives

This issue of Engineering was compiled from papers presented at the First International Conference on Green Plant Protection Innovation(1st ICGPPI),held in Haikou in May 2018,and the Second International Conference on Green Plant Protection Innovation(2nd ICGPPI),held in Guiyang in October 2019.The conferences were sponsored by the Chinese Academy of Engineering,and the Academic Committee of the Forum of the ICGPPI,chaired by Professor Baoan Song,organized the conference.The 1st ICGPPI was attended by more than 800 people from seven countries,while the 2nd ICGPPI had more than 200 attendees from nine countries.The wide range of topics related to more environmentally sound crop protection was of great interest to all,and the meetings provided provided an opportunity for scientists from many disciplines of crop protection to exchange and share ideas and advances.

Effects of (-)-Epigallocatechin gallate on some protein factors involved in the epidermal growth factor receptor signaling pathway

（-）-Epigallocatechin gallate （EGCG）, a major polyphenolic constituent of green tea, can inhibit activity of specific receptor tyrosine kinases （RTKs） and related downstream signal transduction pathways, resulting in the control of unwanted cell proliferation. The epidermal growth factor receptor （EGFR） signaling pathway is one of the most important pathways that regulates growth, survival,proliferation and differentiation in mammalian cells. This review addresses the effects of EGCG on some protein factors involved in the EGFR signaling pathway in a direct or indirect manner. Based on our understanding of the interaction between EGCG and these factors, and based on their structures, EGCG could be used as a lead compound for designing and synthesizing novel drugs with significant biological activity.

Bactericidal bissulfone B7 targets bacterial pyruvate kinase to impair bacterial biology and pathogenicity in plants

The prevention and control of rice bacterial leaf blight(BLB)disease has not yet been achieved due to the lack of effective agrochemicals and available targets.Herein,we develop a series of novel bissulfones and a novel target with a unique mechanism to address this challenge.The developed bissulfones can control Xanthomonas oryzae pv.oryzae(Xoo),and 2-(bis(methylsulfonyl)methylene)-N-(4-chlorophenyl)hydrazine-1-carboxamide(B_(7))is more effective than the commercial drugs thiodiazole copper(TC)and bismerthiazol(BT).Pyruvate kinase(PYK)in Xoo has been identified for the first time as the target protein of our bissulfone B_(7).PYK modulates bacterial virulence via a CRP-like protein(Clp)/two-component system regulatory protein(reg R)axis.The elucidation of this pathway facilitates the use of B_(7)to reduce PYK expression at the transcriptional level,block PYK activity at the protein level,and impair the interaction within the PYK-Clp-reg R complex via competitive inhibition,thereby attenuating bacterial biology and pathogenicity.This study offers insights into the molecular and mechanistic aspects underlying anti-Xoo strategies that target PYK.We believe that these valuable discoveries will be used for bacterial disease control in the future.

Phosphorus speciation in the sediment profile of Lake Erhai, southwestern China: Fractionation and ^(31)P NMR

The distribution characteristics of phosphorus （P） forms in the sediment profile of Lake Erhai, in southwestern China has been investigated by sequential extraction and 31p nuclear magnetic resonance spectroscopy （NMR） of NaOH extracts to understand P dynamics and its potential contribution to lake eutrophication. Contents of P fractions varied in the order of NH4C1 extracted P （NH4C1- P） 〈 bicarbonate-dithionite extracted P （BD-P） 〈 HC1-P, Residual-P 〈 NaOH extracted P （NaOH-P）. The highly available NH4C1-P represented less than 1% of total P （TP）. BD-P and NaOH extracted reactive P （NaOH-rP） averaged 39%, while the ratio of Fe/P was higher than 15, indicating low P release from the sediments under permanent oxic condition. The less bio-available HC1-P, NaOH extracted nonreactive P （NaOH-nrP） and residual-P contributed 61% of TP. Regression analysis revealed that BD-P, NaOH-rP and HC1-P were positively correlated with the contents of Fe and Mn, A1 and Fe, and Ca, respectively. The investigation of P compound groups in NaOH extracts by 31p NMR showed that ortho-P and monoester-P were the largest two constituents of the P pool, followed by diester-P, phosphonate and pyro-P. A comparison of vertical variations of P groups in the sediment profile suggested that these compounds were involved in the P recycling to different extents in Lake Erhai. In particular, the lake exhibits high potential for labile P release from the surface sediments, which should be taken into consideration even after the outsourced P runoff ceased.

Synthesis, Nematicidal Activity, and 3D-QSAR of Novel 1,3,4-Oxadiazole/ Thiadiazole Thioether Derivatives

Forty one novel 1,3,4-oxadiazole/thiadiazole thioether derivatives containing phenoxy moiety were designed and synthesized. Bioassay demonstrated that some of them showed remarkable activities against Tylenchufus semipenetruns in vitro and in vivo. Compounds 20, 21, 35 and 39 showed excellent lethal activities after treatment for 48 h in vitro, with LC50 values of 13.4±1.8, 11.7±2.5, 13.7±2.4 and 13.31.1 mg.L-1, respectively, which were obviously superior to fosthiazate （49.1±2.8 mg.L-1） and avermectin （26.6±2.3 mg.L-1）. Compound 23. can effectively control the citrus nema- tode disease caused by T. semipenetruns at 200 mg.L-1 in vivo with （68±3）% inhibitory effect, which was even better than that of avermectin （（63±2）%）. The CoMFA and CoMSIA models of three-dimensional quantitative structure-activity relationships （3D-QSARs） were established. The compound 33 was designed based on the 3D-QSAR models with more vigorous nematicidal activities in vitro （LC50：9.8±1.4 mg.L-1） and in vivo （（70±5）%）. These results demonstrated that compound 33 can be considered as a potential nematicide.

APPLICATION AND DEVELOPMENT OF ‘GREEN’ PREVENTIVE AND CONTROL TECHNOLOGIES IN GUIZHOU TEA PLANTATIONS

The application and development of ‘green’ preventive technologies in teaplantations is an important means of ensuring tea quality and ecologicalsafety. Ecological, agronomic and biological controls are the main preventivemeasures used in Guizhou Province. This paper summarizes the ‘green’preventive technologies being applied in Guizhou tea plantations, including theuse of plant defense inducers to regulate tea plant responses to pathogens,natural enemies to control pest species causing damage to shoots andTrifolium repens to control the main weed species. In addition, it summarizesthe integrated ‘green’ preventive technologies being used in Guizhou andprovides a foundation for the ecological maintenance of tea plantations.

Design, Synthesis, and Antiviral Activity of Novel Chalcone Derivatives Containing a Purine Moiety

To find new antiviral agents,novel chalcone derivatives containing a purine moiety were designed and synthesized by combining bioactive substructures.The antiviral activities of the derivatives against tobacco mosaic virus （TMV） and cucumber mosaic virus （CMV） were evaluated.Results showed that most of the derivatives showed antiviral activities.Compounds 3n and 3p exhibited excellent curative,protective and inactivation activities against TMV,with the EC50values of 452.4,416.2,241.2 and 438.7,418.6,261.7 μg·mL-1,respectively,which were better than those of ribavirin （585.8,436.0 and 268.7 μg·mL-1）.Compounds 3n and 3p showed remarkable curative and protective activities against CMV.Compound 3n showed a moderate affinity to TMV coat protein,with binding constant Ka and Kd values of 1.5 × 104 L·mol-1 and 79.8 μmol·L-1,respectively.These findings provided an important structural insight for further designs of highly active chalcone derivatives and a basis for further study on their mechanism of action.

Antiviral and Antibacterial Activities of N-（4-Substituted phenyl） Acetamide Derivatives Bearing 1,3,4-Oxadiazole Moiety

In this paper, a series of N-（4-substituted phenyl） acetamide derivatives bearing 1,3,4-oxadiazole moiety were synthesised. Preliminary bioassays revealed that these compounds not only exhibited favourable antiviral activities toward tobacco mosaic virus （TMV） but also demonstrated sustained inhibition activities against plant pathogenic bacteria, including Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Xanthomonas axonopodis pv. cit- ri. Among the derivatives, TC8 and TC20 exerted the strongest curative activities against TMV, with half-maximal effective concentration （EC50） values of 239.5 and 236.2μg/mL, respectively, which were comparable to that of ningnanmycin （EC50=273.2μg/mL）. Given their simple synthesis, the target compounds can serve as alternative antiviral candidates.

Development of solid base catalyst X/Y/MgO/-Al_(2)O_(3) for optimization of preparation of biodiesel from Jatropha curcas L.seed oil

The preparation and regeneration conditions of the identified catalyst X/Y/MgO/?-Al2O3 with high catalytic activity were studied and optimized. The biodiesel was prepared by transesterification of Jatropha curcas seed oil produced in Guizhou with methanol at its reflux temoerature in the presence of X/Y/MgO/?-Al2O3 . The pilot plant tests were carried out in a 100 L reaction vessel. Both average yield and fatty acid methyl esters (FAME) content reached more than 96.50% under the optimum reaction conditions of the pilot plant tests designed with an oil/methanol molar ratio of 1 : 10, catalyst concentration of 1.00%, and reaction time of 3 h at reflux temperature. In addition, analysis shows that the quality of biodiesel meets the standard EN 14214.

The first N-ligand assisted Pd catalyzed asymmetric synthesis of 3-arylsuccinimides as novel antifungal leads

The first palladium/chiral nitrogenous ligand-catalyzed enantioselective addition of aryl boronic acids to various maleimides was reported.This protocol features mild conditions combined with good functional group tolerance.The resultant 3-arylsuccinimides were shown to be novel chiral antifungal leads and inspired the discovery of novel ligands to address the challenging issues of this transformation.