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Contamination of maize with fumonisins depends on the environmental conditions; the maize resistance to contamination and the interaction between both factors. Although the effect of environmental factors is a determinant for establishing the risk of kernel contamination in a region, there is sufficient genetic variability among maize to develop resistance to fumonisin contamination and to breed varieties with contamination at safe levels. In addition, ascertaining which environmental factors are the most important in a region will allow the implementation of risk monitoring programs and suitable cultural practices to reduce the impact of such environmental variables. The current paper reviews all works done to address the influence of environmental variables on fumonisin accumulation, the genetics of maize resistance to fumonisin accumulation, and the search for the biochemical and/or structural mechanisms of the maize plant that could be involved in resistance to fumonisin contamination. We also explore the outcomes of breeding programs and risk monitoring of undertaken projects. ; This research was supported by the National Plan for Research and Development of Spain (AGL2009-12770). R. Santiago acknowledges postdoctoral contracts "Isidro Parga Pondal" supported by the Autonomous Government of Galicia and the European Social Fund and "Ramón y Cajal" supported by the Ministry of Economy and Competitiveness of Spain. ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI). ; Peer reviewed

In cereals, the primary cell wall is built of a skeleton of cellulosic microfibrils embedded in a matrix of hemicelluloses and smaller amounts of pectins, glycoproteins and hydroxycinnamates. Later, during secondary wall development, p-coumaryl, coniferyl and sinapyl alcohols are copolymerized to form mixed lignins. Several of these cell wall components show a determinative role in maize resistance to pest and diseases. However, defense mechanisms are very complex and vary among the same plant species, different tissues or even the same tissue at different developmental stages. Thus, it is important to highlight that the role of the cell wall components needs to be tested in diverse genotypes and specific tissues where the feeding or attacking by the pathogen takes place. Understanding the role of cell wall constituents as defense mechanisms may allow modifications of crops to withstand pests and diseases. ; Studies by the authors' group were supported by the Plan Nacional I+D+I (AGL2003-00961, AGL2006-1314, AGL2009-09611, AGL2012-33415). Nowadays, R. Santiago acknowledges postdoctoral contract "Isidro Parga Pondal" supported by the Autonomous Government of Galicia and the European Social Fund. ; Peer reviewed

The objective of this study was to investigate the stability, across well-differentiated environments, of genetic control of maize resistance to Fusarium graminearum and Fusarium verticillioides ear rots and mycotoxin contamination, found in genotypes of diverse origin and adapted to different environments. This knowledge will help to design the most appropriate breeding programme to reduce mycotoxin content across a wide range of environments. Although maize genetics involved in resistance to ear rots and mycotoxin contamination greatly depended on the environment, additive and dominance effects were the predominant genetic effects in most environments. The stability across environments for resistance to ear rots and deoxynivalenol and fumonisin contamination was low, and recommended target areas of breeding programmes for either Fusarium species are different based on the different nature of genetic effect × environment interactions for each species. In general, the classification of inbreds and hybrids according to their resistance levels was similar across environments, suggesting that the same sources of resistance could be suitable for different environments, and breeding for resistance to one species would affect resistance to the other one. ; This research was supported by the National Plan for Research and Development of Spain (AGL2009-12770). R.S. acknowledges postdoctoral contracts 'Isidro Parga Pondal' supported by the Autonomous Government of Galicia and the European Social Fund and 'Ramón y Cajal' supported by the Ministry of Economy and Competitiveness of Spain. Funding for the Canadian part of this project was in part by an AAFC partnership with the Canadian Field Crop Research Alliance (CFCRA) though AAFC's Developing Innovative Agri-Products Initiative of the Growing Canadian Agri-Innovations Program. ; Ministerio de Economía y Competitividad (España ; Xunta de Galicia ; Agriculture and Agri-Food Canada ; Peer reviewed

This article is the copyright property of the Entomological Society of America and may not be used for any commercial or other private purpose without specific written permission of the Entomological Society of America ; Insect activity has long been associated with Fusarium infection. The objectives of the current study were 1) to estimate the impact of Mediterranean corn borer, Sesamia nonagrioides Lefèbvre, damage on fumonisin contamination in the maize kernel by comparing fumonisin contamination under infestation and protected conditions, and 2) to measure the potential use of genotypes resistant to this borer as controlling factors of fumonisin contamination. Genotypes with increased kernel damage by borers tended to increase fumonisin accumulation under infestation conditions. In particular environments, other factors influenced fumonisin contamination more than damage by borers. When ear damage by borers is significant, maize resistance to ear damage could contribute to the reduction of fumonisin contamination in the kernels. Genotype such as EP42 × EP77 that combines low ear damage by borers and low fumonisin level across environments is a good choice to control fumonisin contamination. The use of an applicable methodology to identify Mediterranean corn borer-resistant genotypes to ear attack under artificial infestations might be a promising approach. © 2013 Entomological Society of America. ; National Plan for Research and Development of Spain ; Autonomous Government of Galicia ; JAE Program of the Spanish Council of Research ; European Social Fund ; This research was supported by the National Plan for Research and Development of Spain (AGL2006-13140, AGL2009-09611) and the Autonomous Government of Galicia(PGIDIT06TAL40301PR). A. Cao acknowledges funding from the JAE Program of the Spanish Council of Research. R. Santiago acknowledges postdoctoral contract "Isidro Parga Pondal" supported by the Autonomous Government of Galicia and the European Social Fund. ; Peer Reviewed

Abstract Background To elucidate the role of the length of the internode basal ring (LIBR) in resistance to the Mediterranean corn borer (MCB), we carried out a divergent selection program to modify the LIBR using two maize synthetic varieties (EPS20 and EPS21), each with a different genetic background. We investigated the biochemical mechanisms underlying the relationship between the LIBR and borer resistance. Selection to lengthen or shorten the LIBR was achieved for each synthetic variety. The resulting plants were analyzed to determine their LIBR response, growth, yield, and borer resistance. Results In the synthetic variety EPS20 (Reid germplasm), reduction of the LIBR improved resistance against the MCB. The LIBR selection was also effective in the synthetic variety EPS21 (non-Reid germplasm), although there was no relationship detected between the LIBR and MCB resistance. The LIBR did not show correlations with agronomic traits such as plant height and yield. Compared with upper sections, the internode basal ring area contained lower concentrations of cell wall components such as acid detergent fiber (ADF), acid detergent lignin (ADL), and diferulates. In addition, some residual 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3-(4H)-one (DIMBOA), a natural antibiotic compound, was detected in the basal area at 30 days after silking. Conclusion We analyzed maize selections to determine whether the basal area of maize internodes is involved in borer resistance. The structural reinforcement of the cell walls was the most significant trait in the relationship between the LIBR and borer resistance. Lower contents of ADF and ADL in the rind of the basal section facilitated the entry of larvae in this area in both synthetic varieties, while lower concentrations of diferulates in the pith basal section of EPS20 facilitated larval feeding inside the stem. The higher concentrations of DIMBOA may have contributed to the lack of correlation between the LIBR and borer resistance in EPS21. This novel trait could be useful in maize breeding programs to improve borer resistance. ; This research was supported by the National Plan for Research and Development of Spain (Projects Cod. AGL2006-13140, AGL 2009-09611). R. Santiago acknowledges postdoctoral contracts "Juan de la Cierva" partially financed by the European Social Fund and "Isidro Parga Pondal" financed by the Autonomous Government of Galicia and the European Social Fund. ; Peer Reviewed

Fusarium graminearum Schwabe is one of the predominant fungal species responsible for stalk rot of maize in Canada and many other countries. Adapted sources of resistance to this disease are scarce but recently a few have been identified. To evaluate the usefulness of these sources in a breeding programme to improve stalk rot resistance, a complete diallel cross of five inbreds of varying susceptibility to stalk rot was conducted. Artificial inoculations of stalks were accomplished by injecting a conidial suspension into the first internode above the uppermost aerial root node. Stalk rot ratings, yield and lodging in the parents, crosses and reciprocals were evaluated over two field seasons. There were significant differences between inbred lines and hybrids for stalk rot ratings. Inbreds CM174 and CO325 were highly susceptible, whereas inbreds 73405 and 73353 were classified as resistant and both had good general combining ability. Those inbreds could be used as donors of favourable alleles in breeding programmes for Gibberella stalk rot resistance. © 2009 Consejo Superior de Investigaciones Cientificas (CSIC). ; Autonomous Government of Galicia (Spain) ; Peer Reviewed

Genetic improvement is an effective and environmentally safe method to reduce the levels of fumonisin mycotoxins in corn kernels infected with Fusarium verticillioides. In order to find new sources of resistance, a wide collection of corn inbred lines were evaluated for Fusarium ear rot and fumonisin accumulation after inoculation of the kernels with Fusarium verticillioides. Augmented designs were used for testing 240 un-replicated inbreds and 6 inbred checks in 2010 and 2011. Sixty-one inbreds were found to have the highest levels of resistance to Fusarium ear rot and fumonisin accumulation across years. Inbreds differing in kernel color, use, kernel type and heterotic group were all represented in this group of 61 inbreds. White corn inbreds had higher levels of fumonisin than yellow corn inbreds, but it was still possible to find white inbreds with comparable resistance to fumonisin accumulation to that of the most resistant yellow inbreds. Similarly, although the sweet corn inbreds evaluated in this study were less resistant to infection by F. verticillioides than the field corn inbreds, there were some which were grouped in the most resistant 61 inbreds. Many of these inbreds can be used to improve resistance to F. verticillioides infection and fumonisin accumulation by crossing the most resistant inbreds of each subgroup. ; MICINN ; Spanish Council of Research. ; Autonomous Government of Galicia ; European Social Fund ; This research was supported by the National Plan for Research and Development of Spain (AGL2009-12770). A. Cao acknowledges funding from the JAE Program of the Spanish Council of Research. R. Santiago acknowledges postdoctoral contract "Isidro Parga Pondal" supported by the Autonomous Government of Galicia and the European Social Fund. ; Peer reviewed

Fusarium ear rot is a common disease of maize that affects food and feed quality globally. Resistance to the disease is highly quantitative, and maize breeders have difficulty incorporating polygenic resistance alleles from unadapted donor sources into elite breeding populations without having a negative impact on agronomic performance. Identification of specific allele variants contributing to improved resistance may be useful to breeders by allowing selection of resistance alleles in coupling phase linkage with favorable agronomic characteristics. We report the results of a genome-wide association study to detect allele variants associated with increased resistance to Fusarium ear rot in a maize core diversity panel of 267 inbred lines evaluated in two sets of environments. We performed association tests with 47,445 singlenucleotide polymorphisms (SNPs) while controlling for background genomic relationships with a mixed model and identified three marker loci significantly associated with disease resistance in at least one subset of environments. Each associated SNP locus had relatively small additive effects on disease resistance (±1.1% on a 0-100% scale), but nevertheless were associated with 3 to 12% of the genotypic variation within or across environment subsets. Two of three identified SNPs colocalized with genes that have been implicated with programmed cell death. An analysis of associated allele frequencies within the major maize subpopulations revealed enrichment for resistance alleles in the tropical/subtropical and popcorn subpopulations compared with other temperate breeding pools. © 2013 Zila et al. ; This research was supported by the National Science Foundation (projects DBI-0321467, IOS- 0820619 and IOS-0604923), USDA-ARS, the National Plan for Research and Development of Spain (AGL2009-12770), and the Excma. Diputación Provincial de Pontevedra. USDA-ARS supported the graduate fellowship of C.T. Zila. R. Santiago acknowledges postdoctoral contract "Isidro Parga Pondal" supported by the Autonomous Government of Galicia and the European Social Fund. ; National Science Foundation ; USDA-ARS ; MICINN ; Excma. Diputación Provincial de Pontevedra ; Autonomous Government of Galicia ; European Social Fund ; Peer Reviewed

[Background] Plant breeding has been proposed as one of the most effective and environmentally safe methods to control fungal infection and to reduce fumonisin accumulation. However, conventional breeding can be hampered by the complex genetic architecture of resistance to fumonisin accumulation and marker-assisted selection is proposed as an efficient alternative. In the current study, GWAS has been performed for the first time for detecting high-resolution QTL for resistance to fumonisin accumulation in maize kernels complementing published GWAS results for Fusarium ear rot. ; [Results] Thirty-nine SNPs significantly associated with resistance to fumonisin accumulation in maize kernels were found and clustered into 17 QTL. Novel QTLs for fumonisin content would be at bins 3.02, 5.02, 7.05 and 8.07. Genes with annotated functions probably implicated in resistance to pathogens based on previous studies have been highlighted. ; [Conclusions] Breeding approaches to fix favorable functional variants for genes implicated in maize immune response signaling may be especially useful to reduce kernel contamination with fumonisins without significantly interfering in mycelia development and growth and, consequently, in the beneficial endophytic behavior of Fusarium verticillioides. ; This research was funded by the Autonomous Government of Galicia, Spain (project IN607A/013), and by the "Secretaría de Estado de Investigación, Desarrollo e Innovación", Spain, within the projects AGL2015–67313-C2–1-R and AGL2015–67313-C2–2-R, which were co-financed with European Social Funds. R. Santiago acknowledges postdoctoral contract "Ramón y Cajal" financed by the "Secretaría de Estado de Investigación, Desarrollo e Innovación" and co-financed by the "Universidad de Vigo", Spain, and the European Social Funds.

8 páginas, 6 figuras y 1 tabla. ; Alternative approaches to linkage and association mapping using inbred panels may allow further insights into loci involved in resistance to Fusarium ear rot and lead to the discovery of suitable markers for breeding programs. Here, the suitability of a maize multiparent advanced generation intercross population for detecting quantitative trait loci (QTLs) associated with Fusarium ear rot resistance was evaluated and found to be valuable in uncovering genomic regions containing resistance-associated loci in temperate materials. In total, 13 putative minor QTLs were located over all of the chromosomes, except chromosome 5, and frequencies of favorable alleles for resistance to Fusarium ear rot were, in general, high. These findings corroborated the quantitative characteristic of resistance to Fusarium ear rot in which many loci have small additive effects. Present and previous results indicate that crucial regions such as 210 to 220 Mb in chromosome 3 and 166 to 173 Mb in chromosome 7 (B73-RefGen-v2) contain QTLs for Fusarium ear rot resistance and fumonisin content. ; This research was funded by the "Plan Estatal de Ciencia y Tecnologia de España" within the projects AGL2015-67313-C2-1-R and AGL2015-67313-C2-2-R, which were co-financed with European Union funds under the FEDER program, and the project IN607A/013 funded by the Autonomous Government of Galicia, Spain. R. Santiago acknowledges postdoctoral contract "Ramón y Cajal" financed by the Ministry of Economy and Competiveness (Spain), Vigo University, and the European Social Fund. ; Peer reviewed

1 página-. Resumen del póster presentado en el Seminario celebrado en Tullm, Austria, entre el 8 y el 11 de abril de 2018. ; In current study, GWAS has been performed for the first time for detecting high-resolution QTL for resistance to fumonisin accumulation in maize kernel. A subset of 270 inbred lines from a maize diversity panel (composed of 302 inbred lines) that represents much of the diversity available in public breeding sector around the world was evaluated under inoculation with Fusarium verticillioides. Significant associations between polymorphisms at SNPs in bins 1.07, 1.09, 2.08, 3.02, 3.04, 3.05, 3.06, 3.08, 3.09, 4.02, 4.05, 5.02, 6.07, 7.05, 8.07, 9.03 and fumonisin accumulation (determined by ELISA tests) in maize kernel were detected. At least, four associations should be behind novel QTL because QTL were not found in that bin or in adjacent bins in previous studies (Robertson-Hoyt et al. 2006; Maschietto et al. 2017). These novel QTLs for fumonisin content would be at bins 3.02, 5.02, 7.05, and 8.03. Genes likely involved in ROS production, ROS-scavenging and ROS-detoxification, in signaling and/or regulation of plant hormone-mediated responses and lipid metabolism were proposed as candidate genes behind significant associations. ; This research was funded by the "Plan Estatal de Ciencia y Tecnologia de España" (project AGL2015-67313-C2-1-R, co-financed with European Union funds under the FEDER program) and by Autonomous Government of Galicia, Spain (projects IN607A/013 and ED431F 2016/014). ; Peer reviewed

Fusarium poses food and feed safety problems because most species produce mycotoxins. To understand the epidemiology of the Fusarium disease, efforts must focus more precisely on how environmental variables affect disease presence. The objectives of the present study were to monitor the occurrence of Fusarium species in maize kernels in northwestern Spain to determine the risk of mycotoxin contamination and to identify environmental traits affecting the composition of the Fusarium species identified. A combination of 24 environments was evaluated. The percentage of kernels infected by F. verticillioides ranged from 33 to 99%, supporting the idea that fumonisin contamination is the main maize-based feed and food safety concern in this area. In this region, temperature and humidity primarily affected Fusarium spp. occurrence. Warmer temperatures during the later stages of kernel development and during kernel drying increased the frequency of F. verticillioides in maize kernels, while the presence of F. subglutinans was increased by higher relative humidity during the silking stage and cooler temperatures during kernel drying. ; This research was supported by the National Plan for Research and Development of Spain (AGL2009-12770), the Autonomous Government of Galicia (PGIDIT06TAL40301PR) and the Deputación de Pontevedra. A. C. acknowledges funding from the JAE Program of the Spanish Council of Research. R. S. acknowledges postdoctoral contract 'Isidro Parga Pondal' supported by the Autonomous Government of Galicia and the European Social Fund. ; Peer reviewed

Genetic improvement is an emerging method to reduce the levels of fumonisin (FB) contamination in maize, but breeding advances depend on the development of suitable methods to accurately assess the performance of different cultivars. Our study focused on characterizing a local isolate of Fusarium verticillioides; comparing artificial inoculation techniques with this isolate (injection into kernels and down the silk channel); and assessing white maize resistance under artificial vs. natural inoculation. The fungal growth rate significantly increased with temperature and water activity a w. The optimum growth rate, corresponding with the shortest phase of initial growth, occurred at 25-30 °C and 0.99 a w. Under silk inoculation with this isolate, the hybrid EP10 × EC22 accumulated significantly less FBs than the other hybrids, whereas, under kernel inoculation, differences among hybrids were not significant (P ≤ 0.05). The local isolate of F. verticillioides produced FBs and responded to the usual environmental conditions during maize kernel ripening in northwestern Spain. Inoculation with this isolate is recommended because it is aggressive, toxigenic, and adapted to the local environment. Silk inoculation was the only method that allowed a clear distinction among genotypes based on differences in resistance to FB accumulation. Resistance to natural and artificial inoculations was confirmed for the hybrid EP10 × EC22. © 2013 KNPV. ; MINECO ; Autonomous Government of Galicia ; Excma. Diputación Provincial de Pontevedra ; Spanish Council of Research ; European Social Fund ; This research was supported by the National Plan for Research and Development of Spain (AGL2009-12770), the Autonomous Government of Galicia (PGIDIT06TAL40301PR) and the Excma. Diputación Provincial de Pontevedra. A. Cao acknowledges funding from the JAE Program of the Spanish Council of Research. R.Santiago acknowledges postdoctoral contract "Isidro Parga Pondal" supported by the Autonomous Government of Galicia and the European Social Fund. ; Peer Reviewed

In Southern Europe where whole maize kernels are ground and used for making bread and other food products, infection of the kernels by Fusarium verticillioides and subsequent fumonisin contamination pose a serious safety issue. The influence of environmental factors on this fungal infection and mycotoxin accumulation as the kernel develops has not been fully determined, especially in such food grade maize. The objectives of the present study were to determine which environmental factors may contribute to kernel invasion by F. verticillioides and fumonisin accumulation as kernels develop and dry in naturally infected white maize. Three maize hybrids were planted at two different sowing dates and kernel samples were collected 20, 40, 60, 80 and 100. days after silking. The percentage of kernels infected, and ergosterol and fumonisin contents were recorded for each sampling. F. verticillioides was the most prevalent species identified as the kernels developed. Temperature and moisture conditions during the first 80. days after silking favored natural kernel infection by F. verticillioides rather than by Aspergillus or Penicillium species. Fumonisin was found in kernels as early as 20. days after silking however significant fumonisin accumulation above levels acceptable in the EU did not occur until after physiological maturity of the kernel indicating that kernel drying in the field poses a high risk. Our results suggest that this could be due to increasing kernel damage by insects that favor fungal development, such as the damage by the moth Sitotroga cerealella, and to the occurrence of stress conditions for F. verticillioides growth that could trigger fumonisin biosynthesis, such as exposure to suboptimal temperatures for growth simultaneously with low water activity. © 2013 Elsevier B.V. ; MICINN ; Spanish Council of Research ; Autonomous Government of Galicia ; European Social Fund ; This research was supported by the National Plan for Research and Development of Spain (AGL2009-12770). A. Cao acknowledges funding from the JAE Program of the Spanish Council of Research. R. Santiago acknowledges postdoctoral contract "Isidro Parga Pondal" supported by the Autonomous Government of Galicia and the European Social Fund. ; Peer Reviewed

The objective of this research was to evaluate the effect of four phenols previously identified at higher concentrations in maize resistant genotypes (p-coumaric acid, ferulic acid, p-hydroxybenzaldehyde and vanillin) on the growth and development of S. nonagrioides larvae. Three different concentrations of each phenolic compound and a mixture of the four were evaluated. Data were recorded on larval and pupal weight, time to pupation and percentage of pupation and mortality. Growth and survival showed no significant differences between the larvae reared on diets with the different treatments and the control. It was concluded that these four compounds, although found in higher concentrations in resistant genotypes, were not toxic to S. nonagrioides in free form under laboratory conditions. Possible ways these compounds could be related with the S. nonagrioides resistance are discussed. © Academic Journals Inc. ; R. Santiago, L. Monetti and B. Ordás acknowledge fellowships from the Autonomous Government of Galicia, Agencia Española de Cooperación Internacional and CSIC respectively. This research was supported by the National Plan for Research and Development of Spain (AGL2001-3736, AGL2003-0961) and the Autonomous Government of Galicia (PGIDIT04PXIC40303PN). ; MICINN ; Xunta de Galicia ; Peer Reviewed