Pyramiding the disease resistant genes to southern rust and stalk rot in maize(Zea mays L.) with marker-assisted selection

Southern corn rust(SCR) caused by Puccinia polysora Underw and maize stalk rot caused by Pythium inflatum Matthews(MSR-2) are two destructive diseases of maize(Zea mays L.) in China.Our previous studies indicated that maize inbred line Qi319 is highly resistant to SCR but susceptible to MSR-2,while inbred line 1145 is highly resistant to MSR-2 but susceptible to SCR.The SCR resistant gene(RppQ) in Qi319 and MSR-2 resistant gene(Rpi1) in 1145 have been mapped on chromosome 10 and 4 respectively.In this research,through marker-assisted selection(MAS) with the molecular markers,bnlg1937 tightly linked to Rpi1 and phi041 tightly linked to RppQ,pyramid breeding of the two kinds of disease resistant genes were carried out from the year of 2003 to 2007.Two homozygotic inbred lines of F5 generation,DR94-1-1-1 and DR36-1-1-1 were identified.MAS result suggested DR94-1-1-1 and DR36-1-1-1 contained the two resistance genes RppQ and Rpi1.Field inoculation tests confirmed their high resistance to the two diseases.In addition,field investigation indicated that the two selected inbred lines,particularly DR94-1-1-1,had excellent agronomic traits such as plant height,ear height and yield-relating traits including ear length,ear diameter,ear weight,kernels per ear,kernels per row and kernel weight per ear.The two selected inbred lines DR94-1-1-1 and DR36-1-1-1 can either be directly developed into commercial variety or used as immediate donors of SCR and MSR resistance breeding programs in maize.

Breeding and Application Techniques of a New Rice Variety Liliang-you 3822 with High Yield and Disease Resistance

Liliangyou 3822 is a novel indica hybrid rice variety that exhibits disease resistance,high yield,lodging resistance,and late maturity.It employs a self-selected two-line sterile line,Li 38S,and a self-selected restorer line,R22.This variety was subjected to a regional test of indica late-maturing groups in the middle and lower reaches of the Yangtze River in 2020.The results demonstrated that the average yield of the variety was 9.95 t/hm 2,which was 10.67%higher than that of the control Fengliangyou 4,indicating a highly significant yield increase.In the continuous test in 2021,the average yield was 9.74 t/hm 2,representing a 6.52%increase over the control,which also exhibited a significant increase.Finally,the average yield of the two years regional test was 9.84 t/hm 2,which was 8.58%higher than that of the control.In the 2021 production test,the average yield of the variety was 9.32 t/hm 2,which was 12.19%higher than that of the control,indicating a remarkably significant yield increase.In 2022,the variety was validated by the National Crop Variety Approval Committee(GSD 20220143).

Utilization of Changyun Jujube, a Cultivar with Resistance to Witches Broom Disease

In 2021,the Shanting District Fruit Industry Service Center conducted an application test of a treatment for jujube witches broom disease using Changyun jujube.The results demonstrated that when diseased Changhong jujube plants were grafted with Changyun jujube in the spring using bark or cleft grafting,the majority of the new shoots of Changyun jujube exhibited no symptoms of witches broom disease,while a few exhibited symptoms of the disease.With the growth of new shoots,the symptoms of witches broom disease gradually abated,returning to normal growth and development.Similarly,the symptoms of witches broom disease on the rootstock below the grafting mouth also gradually abated,returning to normal.The Changyun jujube rootstock was utilized as the intermediate rootstock to grafting the jujube cultivars Qiyuexian and Fucuimi.The two cultivars were subsequently affixed with branch bark from the witches broom disease.The two cultivars did not exhibit any symptoms of witches broom disease,thus providing an opportunity to investigate potential treatments for this disease in jujube.Finally,the cultivation techniques of the Changyun jujube were presented.

Effect of Dietary Resistant Starch on Prevention and Treatment of Obesity-related Diseases and Its Possible Mechanisms

Overweight or obesity has become a serious public health problem in the world, scientists are concentrating their efforts on exploring novel ways to treat obesity. Nowadays, the availabilities of bariatric surgery and pharmacotherapy have enhanced obesity treatment, but it should has support from diet, physical exercise and lifestyle modification, especially the functional food. Resistant starch, an indigestible starch, has been studied for years for its beneficial effects on regulating blood glucose level and lipid metabolism. The aim of this review is to summarize the effect of resistant starch on weight loss and the possible mechanisms. According to numerous previous studies it could be concluded that resistant starch can reduce fat accumulation, enhance insulin sensitivity, regulate blood glucose level and lipid metabolism. Recent investigations have focused on the possible associations between resistant starch and incretins as well as gut microbiota. Resistant starch seems to be a promising dietary fiber for the prevention or treatment of obesity and its related diseases.

Bioinformatics Analysis of Disease Resistance Gene PR1 and Its Genetic Transformation in Soybeans and Cultivation of Multi-resistant Materials

In agricultural production,a single insect-resistant and disease-resistant variety can no longer meet the demand.In this study,the expression vector pCAMBIA-3301-PR1 containing the disease-resistant gene PR1 was constructed by means of genetic engineering,and the PR1 gene was genetically transformed to contain the PR1 gene through the pollen tube method.In CryAb-8Like transgenic high-generation T7 receptor soybean,a new material that is resistant to insects and diseases is obtained.For T2 transformed plants,routine PCR detection,Southern Blot hybridization,fluorescence quantitative PCR detection,indoor and outdoor pest resistance identification and indoor disease resistance identification were performed.The results showed that there were 9 positive plants in the routine PCR test of T2 generation.In Southern Blot hybridization,both PR1 and CryAb-8Like genes are integrated in soybeans in the form of single copies.Fluorescence quantitative PCR showed that the expression levels of PR1 and CryAb-8Like genes are different in different tissues.The average expression levels of PR1 gene in plant roots,stems,and leaves are 2.88,1.54,and 5.26,respectively.CryAb-8Like genes are found in roots,stems,and leaves.The average expression levels were 1.36,1.39,and 4.25,respectively.The insectivorous rate of the CryAb-8Like gene in outdoor plants with positive insect resistance identification was 3.78%.The disc partition method was used indoors for pest resistance identification,and the bud length of transformed plants increased significantly.The average mortality rate of untransformed plants in indoor disease resistance identification was as high as 56.66%,and the average mortality rate of plants transformed with PR1 gene was 10.00%,and disease resistance was significantly improved.Therefore,a new material with resistance to diseases and insects is obtained.

Breeding of High Yield,High Quality and Disease-Resistant Hybrid Cotton Varieties Hanza 160 and Hanza 1692

The hybrid cotton varieties of Hanza 160 and Hanza 1692 were bred by reciprocal crosses between Han 5158 and Han 333 in Hainan and Hebei for several years. Both varieties had the characters of high yield, high quality and disease resistance. Hanza 160 and Hanza 1692 were approved by Hebei Crop Variety Approval Committee in 2013 and 2016, respectively.

Disease-resistant Mechanism of Pepper against Root-Knot Nematode(Meloidogyne spp.)

The biological characteristics,damage symptoms,pathogenic mechanism,prevention and control methods of Meloidogyne spp.in pepper,as well as identification and study of pepper resistance against Meloidogyne spp.are reviewed and summarized.

Studies on Cotton Breeding Resistant to Fusarium and Verticillium wilt Diseases

Both Fusarium and Verticillium wilts are important soil-borne diseases,which can not be effectively controlled by chemical fungicides.The two diseases,especially Verticillium wilt,have

Meta-QTL analysis for mining of candidate genes and constitutive gene network development for fungal disease resistance in maize(Zea mays L.)

The development of resistant maize cultivars is the most effective and sustainable approach to combat fungal diseases.Over the last three decades,many quantitative trait loci(QTL)mapping studies reported numerous QTL for fungal disease resistance(FDR)in maize.However,different genetic backgrounds of germplasm and differing QTL analysis algorithms limit the use of identified QTL for comparative studies.The meta-QTL(MQTL)analysis is the meta-analysis of multiple QTL experiments,which entails broader allelic coverage and helps in the combined analysis of diverse QTL mapping studies revealing common genomic regions for target traits.In the present study,128(33.59%)out of 381 reported QTL(from 82 studies)for FDR could be projected on the maize genome through MQTL analysis.It revealed 38 MQTL for FDR(12 diseases)on all chromosomes except chromosome 10.Five MQTL namely 1_4,2_4,3_2,3_4,and 5_4 were linked with multiple FDR.Total of 1910 candidate genes were identified for all the MQTL regions,with protein kinase gene families,TFs,pathogenesis-related,and disease-responsive proteins directly or indirectly associated with FDR.The comparison of physical positions of marker-traits association(MTAs)from genome-wide association studies with genes underlying MQTL interval verified the presence of QTL/candidate genes for particular diseases.The linked markers to MQTL and putative candidate genes underlying identified MQTL can be further validated in the germplasm through marker screening and expression studies.The study also attempted to unravel the underlying mechanism for FDR resistance by analyzing the constitutive gene network,which will be a useful resource to understand the molecular mechanism of defense-response of a particular disease and multiple FDR in maize.

Identification and expression analysis of sugar transporter family genes reveal the role of ZmSTP2 and ZmSTP20 in maize disease resistance

Sugar is an indispensable source of energy for plant growth and development, and it requires the participation of sugar transporter proteins(STPs) for crossing the hydrophobic barrier in plants. Here, we systematically identified the genes encoding sugar transporters in the genome of maize(Zea mays L.), analyzed their expression patterns under different conditions, and determined their functions in disease resistance. The results showed that the mazie sugar transporter family contained 24 members, all of which were predicted to be distributed on the cell membrane and had a highly conserved transmembrane transport domain. The tissue-specific expression of the maize sugar transporter genes was analyzed, and the expression level of these genes was found to be significantly different in different tissues. The analysis of biotic and abiotic stress data showed that the expression levels of the sugar transporter genes changed significantly under different stress factors. The expression levels of Zm STP2 and Zm STP20 continued to increase following Fusarium graminearum infection. By performing disease resistance analysis of zmstp2 and zmstp20 mutants, we found that after inoculation with Cochliobolus carbonum, Setosphaeria turcica, Cochliobolus heterostrophus, and F. graminearum, the lesion area of the mutants was significantly higher than that of the wild-type B73 plant. In this study, the genes encoding sugar transporters in maize were systematically identified and analyzed at the whole genome level. The expression patterns of the sugar transporter-encoding genes in different tissues of maize and under biotic and abiotic stresses were revealed, which laid an important theoretical foundation for further elucidation of their functions.

Identification and Evaluation of Insect and Disease Resistance in Transgenic Cry1Ab13-1 and NPR1 Maize

PCR detection,quantitative real-time PCR(q-RTPCR),outdoor insect resistance,and disease resistance identification were carried out for the detection of genetic stability and disease resistance through generations(T2,T3,and T4)in transgenic maize germplasms(S3002 and 349)containing the bivalent genes(insect resistance gene Cry1Ab13-1 and disease resistance gene NPR1)and their corresponding wild type.Results indicated that the target genes Cry1Ab13-1 and NPR1 were successfully transferred into both germplasms through tested generations;q-PCR confirmed the expression of Cry1Ab13-1 and NPR1 genes in roots,stems,and leaves of tested maize plants.In addition,S3002 and 349 bivalent gene-transformed lines exhibited resistance to large leaf spots and corn borer in the field evaluation compared to the wild type.Our study confirmed that Cry1Ab13-1 and NPR1 bivalent genes enhanced the resistance against maize borer and large leaf spot disease and can stably inherit.These findings could be exploited for improving other cultivated maize varieties.

Establishment and Application of Identification Methods for Resistance to Sugarcane White Leaf Disease(SCWL)

[Objectives]This study was conducted to establish simple, efficient, stable, standardized and practical identification methods for sugarcane resistance to white leaf disease(SCWL), and promote the breeding for sugarcane resistance to SCWL. [Methods]The identification technology of sugarcane resistance to SCWL was systematically studied and explored from the aspects of sugarcane material treatment and planting, inoculation liquid preparation, inoculation method, disease investigation, grading standard formulation, etc., and two sets of simple, efficient, stable, standardized and practical accurate identification methods for sugarcane resistance to SCWL were created for the first time, namely, the seed cane coating inoculation method and the stem-cutting inoculation method at the growth stage. The seed cane coating inoculation method includes the steps of directly screening SCWL phytoplasma, extracting juice from cane and adding 10 times of sterile water to prepare an inoculation liquid, spraying seed cane on plastic film to keep moisture, planting the inoculated materials in barrels in an insect-proof greenhouse for cultivation, investigating the incidence rate 30 d after inoculation, and evaluating the disease resistance according to the 1-5 level standard. The method of stem-cutting inoculation includes the steps of directly screening sugarcane stems carrying SCWL phytoplasma and adding 10 times of sterile water to prepare an inoculation liquid, cultivating the identification materials in an insect-proof greenhouse, dropping 100 μl of the inoculation liquid into each root incision with a pipette gun at the age of 6 months, investigating the incidence rate 20 d after planting, and evaluating the disease resistance according to the 1-5 level standard. [Results] The two methods are similar to the natural transmission method. After inoculation, SCML occurred significantly, with high sensitivity and good reproducibility. The results of resistance identification were consistent with those of natural disease in the field. Through the two inoculation methods and field natural disease investigation, the resistance of 10 main cultivars to SCML was identified, which was true and reliable. [Conclusions] This study can provide standard varieties for identification of SCML resistance in the future.

OsWRKY65 enhances immunity against fungal and bacterial pathogens in rice

Diverse bacterial and fungal pathogens attack plants,causing biotic stress and severe yield losses globally.These losses are expected to become more serious as climate change improves conditions for many pathogens.Therefore,identifying genes conferring broad-spectrum disease resistance and elucidating their underlying mechanisms provides important resources for plant breeding.WRKY transcription factors affect plant growth and stress responses.However,the functions of many WRKY proteins remain to be elucidated.Here,we demonstrated the role of rice(Oryza sativa)WRKY groupⅢtranscription factor OsWRKY65 in immunity.OsWRKY65 localized to the nucleus and acted as transcriptional repressor.Genetic and molecular functional analyses showed that OsWRKY65 increases resistance to the fungal pathogen Fusarium fujikuroi through downregulation of GA signaling and upregulation of JA signaling.Moreover,OsWRKY65 modulated the expression of the key genes that confer susceptibility or resistance to Xanthomonas oryzae pv.oryzae to enhance immunity against the pathogen.In particular,OsWRKY65directly bound to the promoter region of OsSWEET13 and repressed its expression.Taken together,our findings demonstrate that the OsWRKY65 enhances resistance to fungal and bacterial pathogens in rice.

The OsBSK1-2-MAPK module regulates blast resistance in rice

Receptor-like cytoplasmic kinase OsBSK1-2 was reported to play an important role in regulation of response to rice blast,but the signaling pathway remained unknown.In this study,we identified OsMAPKKK18 and previously uncharacterized MAPKKKs OsMAPKKK16 and OsMAPKKK19 that interact with OsBSK1-2.Expression of all three MAPKKKs was induced by Magnaporthe oryzae infection,and all three induced cell death when transiently expressed in Nicotiana benthamiana leaves.Knockout of OsMAPKKK16 and OsMAPKKK18 compromised blast resistance and overexpression of OsMAPKKK19 increased blast resistance,indicating that all three MAPKKKs are involved in regulation of rice blast response.Furthermore,both OsMAPKKK16 and OsMAPKKK19 interacted with and phosphorylated OsMKK4 and OsMKK5,and chitin-induced MAPK activation was suppressed in osmapkkk16 and osbsk1-2 mutants.OsMAPKKK18 was earlier reported to interact with and phosphorylate OsMKK4 and affect chitin-induced MAPK activation,suggesting that OsBSK1-2 is involved in regulation of immunity through multiple MAPK signaling pathways.Unlike BSK1 in Arabidopsis,OsBSK1-2 was not involved in response to avirulent M.oryzae strains.Taken together,our results revealed important roles of OsMAPKKK16/18/19 and a OsBSK1-2-OsMAPKKK16/18/19-OsMKK4/5 module in regulating response to rice blast.

Sugarcane transcription factor ScWRKY4 negatively regulates resistance to pathogen infection through the JA signaling pathway

WRKY transcription factors,transcriptional regulators unique to plants,play an important role in defense response to pathogen infection.However,the resistance mechanisms of WRKY genes in sugarcane remain unclear.In the present study,gene ontology(GO)enrichment analysis revealed that WRKY gene family in sugarcane was extensively involved in the response to biotic stress and in defense response.We identified gene ScWRKY4,a classⅡc member of the WRKY gene family,in sugarcane cultivar ROC22.This gene was induced by salicylic acid(SA)and methyl jasmonate(MeJA)stress.Interestingly,expression of ScWRKY4 was down-regulated in smut-resistant sugarcane cultivars but up-regulated in smutsusceptible sugarcane cultivars infected with Sporisorium scitamineum.Moreover,stable overexpression of the ScWRKY4 gene in Nicotiana benthamiana enhanced susceptibility to Fusarium solani var.coeruleum and caused down-regulated expression of immune marker-related genes.Transcriptome analysis indicated suppressed expression of most JAZ genes in the signal transduction pathway.ScWRKY4 interacted with ScJAZ13 to repress its expression.We thus hypothesized that the ScWRKY4 gene was involved in the regulatory network of plant disease resistance,most likely through the JA signaling pathway.The present study depicting the molecular involvement of ScWRKY4 in sugarcane disease resistance lays a foundation for future investigation.

Natural variation in maize gene ZmSBR1 confers seedling resistance to Fusarium verticillioides

Maize seedling blight caused by Fusarium verticillioides is a widely occurring maize disease,but the genetics and mechanisms of resistance are not well understood.In this study,GWAS performed by MLM and 3VmrMLM identified 40 and 20 QTNs,associated with seedling blight resistance.These methods identified 49 and 36 genes,respectively.Functional verification of candidate gene ZmSBR1 identified by both methods showed that the resistance of a mutant line to seedling blight decreased by 0.37 grade points after inoculation with F.verticillioides,compared with the WT.The length of the stem rot lesion caused by F.verticillioides increased by 86%in mutant seedlings,and the relative length of the adult plant stalk rot increased by 35%in mutant plants compared to the wild type after inoculation with Fusarium graminearum.Transcriptome analysis showed that expression of defense-related genes after inoculation was down-regulated in the mutant compared to the wild type,synthesis of secondary metabolites associated with resistance was reduced,and the immune response triggered by PAMP decreased,resulting in decreased resistance of mutant maize seedlings.Candidate gene association analysis showed that most maize inbred lines carried the susceptible haplotype.A functional PCR marker was developed.The results demonstrated that ZmSBR1 conferred resistance to multiple Fusarium diseases at the seedling and adult growth stages and had important application value in breeding.

Erratum to “Plant Defense against Necrotrophic Pathogens” [American Journal of Plant Sciences 11(12) (2020) 2122-2138]

The original online version of this article (Ghozlan, M.H., EL-Argawy, E., Tokgöz, S., Lakshman, D.K. and Mitra, A. (2020) Plant Defense against Necrotrophic Pathogens. American Journal of Plant Sciences, 11, 2122-2138. https://doi.org/10.4236/ajps.2020.1112149) was published mistakenly without another co-author, Nikita Gambhir. In this regard, we revise authors and “how to cite” sections by adding her name.

Problems, challenges and future of plant disease management: from an ecological point of view

Plant disease management faces ever-growing challenges due to： （i） increasing demands for total, safe and diverse foods to support the booming global population and its improving living standards; （ii） reducing production potential in agriculture due to competition for land in fertile areas and exhaustion of marginal arable lands; （iii） deteriorating ecology of agro-ecosystems and depletion of natural resources; and （iv） increased risk of disease epidemics resulting from agricultural intensification and monocultures. Future plant disease management should aim to strengthen food security for a stable society while simultaneously safeguarding the health of associated ecosystems and reducing dependency on natural resources. To achieve these multiple functionalities, sustainable plant disease management should place emphases on rational adaptation of resistance, avoidance, elimination and remediation strategies individually and collectively, guided by traits of specific host-pathogen associations using evolutionary ecology principles to create environmental （biotic and abiotic） conditions favorable for host growth and development while adverse to pathogen reproduction and evolution.

Genetic Improvement of Japonica Rice Variety Wuyujing 3 for Stripe Disease Resistance and Eating Quality by Pyramiding Stv-b^i and Wx-mq

Japonica rice variety Kanto 194 as the donor of resistance gene Stv-b^i and Iow-amylose content gene Wx-mq was used to improve the resistance and eating quality of Wuyujing 3 by the breeding strategy of backcross. In continuous backcross and selfcross generations, the related molecular markers with Stvobi and Wx-mq genes were utilized for genotypic detection by associated with resistance identification of rice stripe disease and agronomic traits selection. Finally, 10 improved lines with homozygous genotype Stv-b^i Stv-b^iWx-mqWx-mq were obtained from BC3F4 generation. The results of comparative analysis indicated that most characters of these lines were consistent with those of recipient parent Wuyujing 3, except for the improved resistance, appearance and eating quality. By evaluation of the comprehensive performance of them, two excellent lines K01 and K04 were selected for further experiments.

Inheritance Analysis and Identification of SSR Markers Linked to Late Blight Resistant Gene in Tomato

Late blight caused by Phytophthora infestans is the most serious disease of tomato production in China. Studies on the genetics of resistance and identification of molecular markers are very useful for breeding late blight resistant varieties. The objective of this paper was to study the inheritance of late blight resistance and identify simple sequence repeat （SSR） markers associated with resistance allele in tomato （Lycopersicon esculentum Mill）. The results came from an F2 progeny of 241 plants derived from a cross between 5~ inbred line that is susceptible to late blight and a resistant accession CLN2037E. The late blight responses of F2 plants were tested by artificially inoculation of detached-leaflets in plate and natural infection assayed under greenhouse conditions. Both methods showed that the resistance is dominant and inherited as monogenic trait. Genetic mapping and linkage analysis showed that the late blight resistance gene Ph-ROL was located on chromosome 9 with a genetic distance of 5.7 cM to the SSR marker TOM236.