Fusarium Ear Rot Research Articles

Інтегрований хімічний захист кукурудзи від фузаріозу початків в умовах правобережного лісостепу України

У статті наведено результати польових експериментальних досліджень ефективності фунгіциду Амістар Екстра 280 SC проти фузаріозу початків кукурудзи на штучному інфекційному фоні. Обприскування проводили у різні строки відносно штучного зараження початків збудником фузаріозу. Ступінь розвитку хвороби на контрольному варіанті складала 27,1 % на середньостиглому гібриді Аурум та 28,7 % на середньопізньому гібриді Штандарт. Найвища біологічна ефективність від застосування фунгіциду складала відповідно 51 % на гібриді Аурум та 41 % на гібриді Штандарт. Найоптимальнішим строком обприскування проти фузаріозу кукурудзи є 3 доба до штучного зараження початків збудником. Встановлено пряму залежність збільшення ураження фузаріозом за збільшення ураження початків кукурудзяним стебловим метеликом. Варіанти, оброблені інсектицидом, мали нижчі показники ураження фузаріозом початків у порівнянні з контролем у середньому на 30-50 %. Недобір врожаю в порівнянні з необробленими інсектицидом варіантами в середньому складав 0,9-1,3 т/га. Ключові слова: кукурудза, оптимальні строки, фунгіцид, фузаріоз початків, біологічна ефективність, розвиток хвороби, кукурудзяний стебловий метелик

The effect of Busseola fusca infestation, fungal inoculation and mechanical wounding on Fusarium ear rot development and fumonisin production in maize

Fusarium verticillioides and Busseola fusca are among the most significant biotic constraints to maize production in South Africa. In this study, the effect of B. fusca damage and mechanical wounding to maize ears on Fusarium ear rot development and fumonisin production was investigated. The effect of the interaction on Fusarium ear rot and B. fusca damage was studied by inoculating maize ears with F. verticillioides isolate MRC826 and infesting plant whorls with aliquots of 10–15 neonate larvae at the 12th leaf stage prior to tasselling. To simulate hail damage, maize ears were mechanically wounded at the blister stage with cork borers of different sizes and number of wounds, with and without F. verticillioides inoculation. Uninoculated, uninfested and undamaged control treatments were included. Field trials were conducted over three seasons using a randomised complete block design with six replicates per treatment. In all seasons, most Fusarium ear rot developed on ears inoculated with F. verticillioides. This study indicated that B. fusca infestation was not associated with higher Fusarium ear rot incidence in two of the three seasons. Moreover, B. fusca infestation was not associated with high fumonisin production in any season. This indicates that the presence of B. fusca was not highly associated with Fusarium ear rot or fumonisin production, possibly due to its characteristic feeding nature that causes sporadic wounds on maize ears, but also the strong impact of weather variability. Fusarium ear rot development and fumonisin production by F. verticillioides inoculum varied seasonally indicating the importance of environmental conditions on Fusarium ear rot and fumonisin production. Fusarium ear rot and fumonisin production significantly increased with the severity of cork borer wounding in both naturally infected and artificially inoculated maize ears. Therefore, the prevention of severe injuries to kernels, whether by mechanical damage or insects, should be considered as important in reducing Fusarium ear rot and fumonisin production in maize.

The Reaction of some Maize Hybrids, Created at ARDS TURDA, to Fusarium spp. Infection

The most important disease of maize in Romania are stalk and ear rot, which caused yield losses in average of 20%. The resistant hibrids represent one of the most efficient solution for reducing the field loses caused by Fusarium spp. on the maize (Nagy et al., 2006). Diseases caused by Fusarium spp. can affect the yield and grain quality of maize because of contamination with numerous mycotoxins produced by these fungi (Czembor et al., 2015). The purpose of this paper was to know more about the reaction of different maize hybrids to Fusarium and the evaluating the effect of ear rot on the yield ability and mycotoxins accumulation. The experiments carried out at ARDS Turda, during four years (2012-2015). The biological material was represented by 8 hybrids, from different maturity groups, tested in two infection conditions with Fusarium spp. (natural and artificial infections). The temperature and rainfalls of the four years of experiments corresponding to the vegetation of maize (april-september) are influenced favourably the pathogenesis of stalk and ear rot caused by Fusarium spp. and a good discrimination of the resistance reaction of genotypes. Fusarium ear rot has significantly affected production capacity and chemical composition of corn hybrids tested. In conditions of artificial infection with Fusarium spp. was a decrease in the content of starch, fat and increased protein content compared with artificially inoculated variants. The quantity of fumonizin B1+B2 has reached to 5630 μg/kg in conditions of artificial infection. There are negative correlations between production capacity and degree of attack of fusarium ear rot; depending on the reacting genotypes tested increasing disease causes production decrease. The response of maize hybrids to Fusarium infection is influenced by infection and climatic conditions. These factors affect production both in terms of quantity and quality and accumulation of mycotoxins.

Fusarium diseases of maize associated with mycotoxin contamination of agricultural products intended to be used for food and feed.

Infections of maize with phytopathogenic and toxinogenic Fusarium spp. may occur throughout the cultivation period. This can cause different types of diseases in vegetative and generative organs of the plant. Along with these infections, mycotoxins are often produced and accumulated in affected tissues, which could pose a significant risk on human and animal health when entering the food and feed chain. Most important fungal species infecting European maize belong to the Fusarium sections Discolour and Liseola, the first being more prevalent in cooler and humid climate regions than the second predominating in warmer and dryer areas. Coexistence of several Fusarium spp. pathogens in growing maize under field conditions is the usual case and may lead to multi-contamination with mycotoxins like trichothecenes, zearalenone and fumonisins. The pathways how the fungi gain access to the target organs of the plant are extensively described in relation to specific symptoms of typical rot diseases regarding ears, kernels, rudimentary ears, roots, stem, leaves, seed and seedlings. Both Gibberella and Fusarium ear rots are of major importance in affecting the toxinogenic quality of grain or ear-based products as well as forage maize used for human or animal nutrition. Although rudimentary ears may contain high amounts of Fusarium toxins, the contribution to the contamination of forage maize is minor due to their small proportion on the whole plant dry matter yield. The impact of foliar diseases on forage maize contamination is regarded to be low, as Fusarium infections are restricted to some parts on the leaf sheaths and husks. Mycotoxins produced in rotted basal part of the stem may contribute to forage maize contamination, but usually remain in the stubbles after harvest. As the probability of a more severe disease progression is increasing with a prolonged cultivation period, maize should be harvested at the appropriate maturity stage to keep Fusarium toxin contamination as low as possible. Ongoing surveillance and research is needed to recognise changes in the spectrum of dominating Fusarium pathogens involved in mycotoxin contamination of maize to ensure safety in the food and feed chain.

Розвиток фузаріозу початків кукурудзи на гібридах різних груп стиглості та його шкідливість в умовах Правобережного Лісостепу України

Maize ( Zea mays L. ) is one of the most strategically and economically important crop in worldwide together with wheat and rice. But, as the rest of the other grain crops maize is suffering from different diseases which affect almost all plant’s parts. Among of maize diseases – ear rots are supposed as the most widespread and harmful. The most common disease of maize ears in most regions of maize cultivating in Ukraine is fusarium ear rot (dominant causative agent - the fungus Fusarium verticillioides (Sacc.) Nirenberg; Teleomorph: Giberella moniliformis Wineland; synonym: F.moniliformis ). Every year maize disease cause yield losses which in some years can reach 30.0% and more. Fusarium ear rot can cause serious damage to all types of corn. The incidence of the disease largely depends on weather conditions and occurrence of maize plants damaged by European corn borer ( Ostrinia nubilalis ). The main damage from the disease are direct losses of grain at the start and hidden, affecting the yield and quality. Besides developing at the beginning period of storage (humidity exceeding 18%), the pathogen of Fusarium verticillioides , producing toxins (fumonisins) can cause poisoning effect on humans and animals. The aim of the research was to analyze the interrelation of maize hybrids of various maturity to Fusarium ear rot intensity and to study disease harmfulness in terms of Right bank Forest Steppe zone of Ukraine Maize pathology monitoring of research plots of maize with different maturity group showed that hybrids four maturity terms were affected by Fusarium pathogen in different degrees. Weather conditions also had a significant impact on the severity of Fusarium ear rot. Figures 1,2,3,4 image average air temperature and amount of rainfall in the growing seasons of maize in 2015 and 2016. Per the weather conditions were more favorable for the disease in 2016. In addition, setting experiments in isolated areas of forest belts planting corn in monoculture (4-5 years) contributed to the accumulation of European corn borer which promote the incidence of Fusarium infection. According to received research data the most Fusarium incidence was seen on hybrids of middle-early and mid-season groups of maturity, which respectively accounted for 28.3 and 27.0% (2015) and 30.1 and 30.3% (2016). Similarly, the disease severity was 2.9 and 5.0% (2015) and 3.2 and 10.0% (2016). On average, for two years of Fusarium intensity these variants are accounted for 29.2 and 28.7%, and growth of 3.1 and 7.5% respectively. The remaining maize hybrids from other maturity groups occupy an intermediate position of the disease intensity. The maize yield according to Fusarium ear rot harmfulness in 2016 was lower on middle-early and average-late hybrids by an average of 0.5 t/ha relative to 2015, and the early- and mid-season yield respectively was lower by an average of 0.3 t/ha. In the 2015-2016 dominant role among the major maize ear diseases had Fusarium ear rot (dominant causative agent - the fungus Fusarium verticillioides (Sacc.) Nirenberg). The most favorable weather conditions for the development of Fusarium ear rot were in 2016. Found that most Fusarium ear rot intensity was observed on average-late maize hybrids, which incidence were 20 to 27% level, and severity from 5% and higher. Yield losses depending on the degree of disease intensity were varied from 0.3 to 0.5 t/ha.

Determining resistance to Fusarium verticillioides and fumonisin accumulation in African maize inbred lines resistant to Aspergillus flavus and aflatoxins

Fusarium verticillioides and Aspergillus flavus cause Fusarium ear rot (FER) and Aspergillus ear rot (AER) of maize, respectively. Both pathogens are of concern to producers as they reduce grain yield and affect quality. F. verticillioides and A. flavus also contaminate maize grain with the mycotoxins fumonisins and aflatoxins, respectively, which has been associated with mycotoxicosis in humans and animals. The occurrence of common resistance mechanisms to FER and AER has been reported. Hence, ten Kenyan inbred lines resistant to AER and aflatoxin accumulation were evaluated for resistance to FER, F. verticillioides colonisation and fumonisin accumulation; and compared to nine South African lines resistant to FER and fumonisin accumulation. Field trials were conducted at three localities in South Africa and two localities in Kenya. FER severity was determined by visual assessment, while F. verticillioides colonisation and fumonisin content were quantified by real-time PCR and liquid chromatography tandem mass spectrometry, respectively. Significant genotype x environment interactions was determined at each location (P ≤ 0.05). Kenyan inbred CML495 was most resistant to FER and F. verticillioides colonisation, and accumulated the lowest concentration of fumonisins across localities. It was, however, not significantly more resistant than Kenyan lines CML264 and CKL05015, and the South African line RO549 W, which also exhibited low FER severity (≤5%), fungal target DNA (≤0.025 ng μL−1) and fumonisin levels (≤2.5 mg kg−1). Inbred lines resistant to AER and aflatoxin accumulation appear to be promising sources of resistance to F. verticillioides and fumonisin contamination.

Diallel analysis of resistance to Fusarium ear rot in Brazilian popcorn genotypes

Among the ear rot pathogens, species of Fusarium cause significant economic losses to popcorn production. To generate popcorn genotypes resistant to Fusarium ear rot, the combining ability of popcorn lines in diallel crosses were assessed during two cropping years: the first from Mar to Sep 2015 and the second from Sep 2015 to Jan 2016. The traits analyzed were: average ear weight (AEW, kg ha−1); grain yield (GY, kg ha−1); popping expansion (PE, g mL−1), Fusarium incidence on ears (EIFU, %); Fusarium ear rot severity index (FSI, %), percentage of fungal-infected kernels (KIF), and percentage of Fusarium-infected kernels (KIFU). Non-additive genetic effects prevailed in the expression of resistance to Fusarium ear rot and grain yield, while additive effects were the most prominent in the expression of popping expansion. Among 56 hybrids, seven showed outstanding grain yield, desirable popping expansion, and resistance to Fusarium ear rot. The less susceptible hybrids to ear rot produced high grain yield and popping expansion. Two disease-related traits, KIFu and EIFu, allowed to best differentiate among the genotypes.

QTL mapping and candidate genes for resistance to Fusarium ear rot and fumonisin contamination in maize

BackgroundFusarium verticillioides is a common maize pathogen causing ear rot (FER) and contamination of the grains with the fumonisin B1 (FB1) mycotoxin. Resistance to FER and FB1 contamination are quantitative traits, affected by environmental conditions, and completely resistant maize genotypes to the pathogen are so far unknown. In order to uncover genomic regions associated to reduced FER and FB1 contamination and identify molecular markers for assisted selection, an F2:3 population of 188 progenies was developed crossing CO441 (resistant) and CO354 (susceptible) genotypes. FER severity and FB1 contamination content were evaluated over 2 years and sowing dates (early and late) in ears artificially inoculated with F. verticillioides by the use of either side-needle or toothpick inoculation techniques.ResultsWeather conditions significantly changed in the two phenotyping seasons and FER and FB1 content distribution significantly differed in the F3 progenies according to the year and the sowing time. Significant positive correlations (P < 0.01) were detected between FER and FB1 contamination, ranging from 0.72 to 0.81. A low positive correlation was determined between FB1 contamination and silking time (DTS). A genetic map was generated for the cross, based on 41 microsatellite markers and 342 single nucleotide polymorphisms (SNPs) derived from Genotyping-by-Sequencing (GBS). QTL analyses revealed 15 QTLs for FER, 17 QTLs for FB1 contamination and nine QTLs for DTS. Eight QTLs located on linkage group (LG) 1, 2, 3, 6, 7 and 9 were in common between FER and FB1, making possible the selection of genotypes with both low disease severity and low fumonisin contamination. Moreover, five QTLs on LGs 1, 2, 4, 5 and 9 located close to previously reported QTLs for resistance to other mycotoxigenic fungi. Finally, 24 candidate genes for resistance to F. verticillioides are proposed combining previous transcriptomic data with QTL mapping.ConclusionsThis study identified a set of QTLs and candidate genes that could accelerate breeding for resistance of maize lines showing reduced disease severity and low mycotoxin contamination determined by F. verticillioides.

Characterization and pathogenicity of Fusarium proliferatum andFusarium verticillioides, causal agents of Fusarium ear rot of corn

Fusarium ear rot is a significant disease of corn caused by several toxigenic Fusarium species including Fusarium proliferatum and Fusarium verticillioides. Forty-one Fusarium isolates were recovered from corn with Fusarium ear rot disease symptoms collected from Peninsular Malaysia. Isolates were classified into three described species known as F. proliferatum, F. verticillioides, and F. solani. Based on sexual compatibility test, four isolates from F. proliferatum (MATD-1) were crossed-fertile with tester isolate F. proliferatum D024853 (MATD-2), producing perithecia in the presence of ascospores. Meanwhile, the isolates from F. verticillioides (MATA-2) were crossed with tester isolate F. verticillioides A00149 (MATA-1), but were found producing 11 isolates with barren perithecia and three infertile isolates, whereas in 11 isolates of F. verticillioides (MATA-1), seven isolates produced barren perithecia with four nonfertile isolates. In the pathogenicity test, all isolates were found pathogenic and displayed disease symptoms with variation in severity. The highest disease severity index value was observed in F. proliferatum B68c at 4.67, which was obtained in an updated report on the mating type of F. verticillioides and F. proliferatum isolated from Fusarium ear rot disease.

First report of Fusarium temperatum causing ear rot on maize in Italy

A two-year survey (2011-2012) was conducted to determine the population composition of Fusarium species on maize (Zea mays L.) in Lombardy (northern Italy). Maize ears exhibiting typical symptoms of Fusarium ear rot (FER) (about 30%), such as white to pink colored mycelia on the tip or scattered all over the ear, were collected at harvest. Rotted kernels were surface sterilized, rinsed in sterile water, dried and placed on potato dextrose agar (PDA) amended with dichloran and antibiotics. Developed Fusarium colonies were single-spore purified and grown on Spezieller Nahrstoffarmer agar (Leslie and Summerell, 2006). Based on morphological characteristics, 15 Fusarium spp. strains were identified as Fusarium subglutinans. Colonies on PDA showed a cottony aerial mycelium, initially white, becoming pinkish white. No microconidia chains were detected, conidiophores were erect and terminated in one to three phialides. Macroconidia were falcate, three to five septate, with a slightly beaked apical cell and a barely or distinct footlike basal cell. The translation elongation factor-1α (EF-1α) gene was partially sequenced for all the F. subglutinans strains using primers EF1 and EF2 (Scauflaire et al., 2011). BLASTn analysis showed that the nucleotide sequence (673 bp) of one strain (isolate GV2188, GenBank Accession No. KX156836) shared 100% sequence identity with F. temperatum (HM067689), a recently described species closely related to F. subglutinans (Scauflaire et al., 2011). Using silk channel inoculation method, F. temperatum pathogenicity was assessed on 10 maize ears (LG 32.85 hybrid) under greenhouse conditions. After 30 days, FER symptoms, i.e. whitish pink to lavender fungal growth on kernels, were observed only on inoculated ears and not on water controls. Koch's postulates were fulfilled by re-isolating the fungus from infected kernels. To our knowledge, this is the first report of F. temperatum in Italy associated with FER.

Genome-Wide Association Study and QTL Mapping Reveal Genomic Loci Associated with Fusarium Ear Rot Resistance in Tropical Maize Germplasm.

Fusarium ear rot (FER) incited by Fusarium verticillioides is a major disease of maize that reduces grain quality globally. Host resistance is the most suitable strategy for managing the disease. We report the results of genome-wide association study (GWAS) to detect alleles associated with increased resistance to FER in a set of 818 tropical maize inbred lines evaluated in three environments. Association tests performed using 43,424 single-nucleotide polymorphic (SNPs) markers identified 45 SNPs and 15 haplotypes that were significantly associated with FER resistance. Each associated SNP locus had relatively small additive effects on disease resistance and accounted for 1–4% of trait variation. These SNPs and haplotypes were located within or adjacent to 38 candidate genes, 21 of which were candidate genes associated with plant tolerance to stresses, including disease resistance. Linkage mapping in four biparental populations to validate GWAS results identified 15 quantitative trait loci (QTL) associated with F. verticillioides resistance. Integration of GWAS and QTL to the maize physical map showed eight colocated loci on chromosomes 2, 3, 4, 5, 9, and 10. QTL on chromosomes 2 and 9 are new. These results reveal that FER resistance is a complex trait that is conditioned by multiple genes with minor effects. The value of selection on identified markers for improving FER resistance is limited; rather, selection to combine small effect resistance alleles combined with genomic selection for polygenic background for both the target and general adaptation traits might be fruitful for increasing FER resistance in maize.

Crops are a main driver for species diversity and the toxigenic potential ofFusarium isolates in maize ears in China

In recent years increasing demands and the relatively low-care cultivation of the crop have resulted in an enormous expansion of the acreage of maize in China. However, particularly in China,Fusariumear rot forms an important constraint to maize production. In this study, we showed that members of both theFusarium fujikuroispecies complex (FFSC) and theFusarium graminearumspecies complex are the causal agents ofFusariumear rot in the main maize producing areas in China. Fumonisin producingFusarium verticillioideswas the most prevalent species, followed by fumonisin producingFusarium proliferatumand 15-acetyldeoxynivalenol producingF. graminearum. BothFusarium temperatumandFusarium boothiiwere identified for the first time in the colder regions in China, extending their known habitats to colder environments. Mating type analysis of the different heterothallic FFSC species, showed that both types co-occur in each sampling site suggestive of the possibility of sexual recombination. Virulence tests withF. boothii(from maize) andF. graminearumfrom maize or wheat showed adaptation to the host. In addition,F. graminearumseems to outcompeteF. boothiiin wheat-maize rotations. Based on our findings and previous studies, we conclude that wheat/maize rotation selects forF. graminearum, while a wheat/rice rotation selects forF. asiaticum. In contrast,F. boothiiis selected when maize is cultivated without rotation. A higher occurrence ofF. temperatumis observed on maize in colder climatological regions in China, whileFusarium meridionaleseems restricted to mountain areas. Each of these species has their characteristic mycotoxin profile and deoxynivalenol and fumonisin are the potential threats to maize production in Northern China.

Mycotoxins and related Fusarium species in preharvest maize ear rot in Poland

This work presents a survey on mycotoxins (seasons 2013 and 2014) and Fusarium species (seasons from 1985 to 2014) in maize ear rot in Poland. Twelve mycotoxins were identified in maize kernel samples exhibiting symptoms of Fusarium ear rot or rotten kernels at the harvest in two locations in Poland during the seasons 2013 and 2014. This is the first complex survey on the co-occurrence of four Fusarium mycotoxin groups in maize kernels: the group of the mycohormone zearalenone; the group of trichothecenes – deoxynivalenol and nivalenol; the group of fumonisins; and the group of cyclic hexadepsipeptides – beauvericin and enniatins; and in addition, moniliformin. Four Fusarium species were identified in preharvest maize ear rot in the 2013 and 2014 harvests namely:&lt;br /&gt; F. graminearum, F. poae, F. subglutinans and F. verticillioides. Since 1985, eleven Fusarium species have been identified in 13 investigation seasons. Apart from those mentioned above, F. avenaceum, F. cerealis, F. culmorum and&lt;br /&gt; F. sporotrichioides were observed with irregular frequencies, and three species, i.e. F. proliferatum, F. tricinctum and F. equiseti, were identified sporadically. A significant increase of F. verticillioides frequency and a decrease of F. subglutinans frequency and changes of mycotoxin profile have been observed in the two decades since 1995.

Multi-environment Evaluation of Maize Inbred Lines for Resistance to Fusarium Ear Rot and Fumonisins.

Fusarium verticillioides causes Fusarium ear rot (FER) of maize and produces fumonisins, which affects grain quality. Host-plant resistance can reduce both FER and fumonisins in maize. In this study, 18 maize inbred lines were evaluated for resistance to F. verticillioides and fumonisin accumulation at five localities in South Africa. Additive main effects and multiplicative interaction analyses revealed significant environment × genotype interactions, with inbred lines CML 390, US 2540W, RO 424W, and VO 617y-2 consistently exhibiting low FER severity (≤5.4%), fungal target DNA (≤0.1 ng μl-1), and fumonisin levels (≤5.6 ppm). Genotype main effect and genotype × environment biplots showed that inbred lines CML 390, US 2540W, and RO 424W were most resistant to FER, fungal colonization, and fumonisin accumulation, respectively, while inbred line RO 424W was most stable in its resistance response over environments. These inbred lines also demonstrated broad adaptability by consistently exhibiting resistance to FER, fungal colonization, and fumonisins across localities. The identified lines could serve as valuable sources of resistance against F. verticillioides and its fumonisins in local breeding programs.

Identification of molecular markers linked to Fusarium ear rot genes in maize plants Zea mays L

ABSTRACTTwo maize populations (GE440 × Sd7 and NC300 × Gm1002) were used in this study. Molecular markers like simple sequence repeat (SSR) and sequence-tagged site (STS) were used to identify resistance genes linked to Fusarium ear rot (Fusarium verticillioides). Also, quantitative trait locus (QTL) mapping was used to detect resistance genes on maize chromosomes. The co-dominant microsatellite markers (bnlg1063, umc2082, bnlg1621, umc2013, bnlg1740, umc2059 and SSR85) and STS (STS06) were amplified polymorphic bands and candidate markers linked to Fusarium ear rot resistance genes in maize. Seven QTLs were identified ranging from 2 to 7 for each trait. QTLs were distributed on two chromosomes and associated with grain yield/main ear and 100 kernel weight. The present study indicated that microsatellite and STS primers might be useful for developing improved cultivars.

A multi-environment trials diallel analysis provides insights on the inheritance of fumonisin contamination resistance in tropical maize

In maize, the fungi that cause Fusarium ear rot result not only in decreased grain yield and quality, but also grain contamination by fumonisin. This study investigated the inheritance of fumonisin contamination resistance (FCR) in tropical maize, based on a multi-environment trials diallel analysis via mixed models. For this purpose, based on 13 inbred lines, single-cross hybrids were created and assessed in three environments. A mixed model diallel joint analysis across environments was performed, considering the existence of environment-specific variances and correlations between pairs of environments for general combining ability (GCA) and specific combining ability (SCA) effects, and additive genomic relationship between inbred lines for the prediction of GCA and SCA. For all environments, the SCA variance had a higher magnitude than the GCA variance, indicating a predominance of the dominance effects underlying FCR in tropical maize. Moreover, the proportion of the variance among single-cross hybrids that was due to GCA varied from 16 to 22 % across environments, suggesting that SCA is important to predict the hybrids performance. Through modeling variance–covariance structures for GCA and SCA, it was possible to observe that the GCA effects were stable, whereas the SCA effects were specific for each environment. Therefore, these results suggest that the selection of the best parents for the development of new inbred lines can be carried out through the average performance across the evaluated environments. Due to the importance of SCA effects and their complex interaction with environments, the selection of superior hybrids should be performed into specific environments.

Direct and host‐mediated interactions between Fusarium pathogens and herbivorous arthropods in cereals

Fusarium head blight and fusarium ear rot diseases of cereal crops are significant global problems, causing yield and grain quality losses and accumulation of harmful mycotoxins. Safety limits have been set by the European Commission for several Fusarium‐produced mycotoxins; mitigating the risk of breaching these limits is of great importance to crop producers as part of an integrated approach to disease management. This review examines current knowledge regarding the role of arthropods in disease epidemiology. In the field, diseased host plants are likely to interact with arthropods that may substantially impact the disease by influencing spread or condition of the shared host. For example, disease progress by Fusarium graminearum can be doubled if wheat plants are aphid‐infested. Arthropods have been implicated in disease epidemiology in several cases and the evidence ranges from observed correlations between arthropod infestation and increased disease severity and mycotoxin accumulation, to experimental evidence for arthropod infestation causing heightened pathogen prevalence in hosts. Fusarium pathogens differ in spore production and impact on host volatile chemistry, which influences their suitability for arthropod dispersal. Herbivores may allow secondary fungal infection after wounding a plant or they may alter host susceptibility by inducing changes in plant defence pathways. Post‐harvest, during storage, arthropods may also interact with Fusarium pathogens, with instances of fungivory and altered behaviour by arthropods towards volatile chemicals from infected grain. Host‐mediated indirect pathogen–arthropod interactions are discussed alongside a comprehensive review of evidence for direct interactions where arthropods act as vectors for inoculum.

Antioxidant Secondary Metabolites in Cereals: Potential Involvement in Resistance to Fusarium and Mycotoxin Accumulation.

Gibberella and Fusarium Ear Rot and Fusarium Head Blight are major diseases affecting European cereals. These diseases are mainly caused by fungi of the Fusarium genus, primarily Fusarium graminearum and Fusarium verticillioides. These Fusarium species pose a serious threat to food safety because of their ability to produce a wide range of mycotoxins, including type B trichothecenes and fumonisins. Many factors such as environmental, agronomic or genetic ones may contribute to high levels of accumulation of mycotoxins in the grain and there is an urgent need to implement efficient and sustainable management strategies to reduce mycotoxin contamination. Actually, fungicides are not fully efficient to control the mycotoxin risk. In addition, because of harmful effects on human health and environment, their use should be seriously restricted in the near future. To durably solve the problem of mycotoxin accumulation, the breeding of tolerant genotypes is one of the most promising strategies for cereals. A deeper understanding of the molecular mechanisms of plant resistance to both Fusarium and mycotoxin contamination will shed light on plant-pathogen interactions and provide relevant information for improving breeding programs. Resistance to Fusarium depends on the plant ability in preventing initial infection and containing the development of the toxigenic fungi while resistance to mycotoxin contamination is also related to the capacity of plant tissues in reducing mycotoxin accumulation. This capacity can result from two mechanisms: metabolic transformation of the toxin into less toxic compounds and inhibition of toxin biosynthesis. This last mechanism involves host metabolites able to interfere with mycotoxin biosynthesis. This review aims at gathering the latest scientific advances that support the contribution of grain antioxidant secondary metabolites to the mechanisms of plant resistance to Fusarium and mycotoxin accumulation.

Assessing pigmented pericarp of maize kernels as possible source of resistance to fusarium ear rot, Fusarium spp. infection and fumonisin accumulation

One of the purposes of maize genetic improvement is the research of genotypes resistant to fusarium ear rot (FER) and fumonisin accumulation. Flavonoids in the pericarp of the kernels are considered particularly able to reduce the fumonisin accumulation (FUM). The aim of this field study was to assess the effect of flavonoids, associated with anti-insect protection and Fusarium verticillioides inoculation, on FER symptoms and fumonisin contamination in maize kernels. Two isogenic hybrids, one having pigmentation in the pericarp (P1-rr) and the other without it (P1-wr), were compared. P1-rr showed lower values of FER symptoms and FUM contamination than P1-wr only if the anti-insect protection and the F. verticillioides inoculations were applied in combination. Fusarium spp. kernel infection was not influenced by the presence of flavonoids in the pericarp. Artificial F. verticillioides inoculation was more effective than anti-insect protection in enhancing the inhibition activity of flavonoids toward FUM contamination. The interactions between FUM contamination levels and FER ratings were better modeled in the pigmented hybrid than in the unpigmented one. The variable role that the pigment played in kernel defense against FER and FUM indicates that flavonoids alone may not be completely effective in the resistance of fumonisin contamination in maize.

Evaluation on reaction of early maturing maize lines and hybrids to fusarium ear rot

In order to investigate the amount of resistance in and early maturity lines and hybrids to ear rot fusarium disease, an experiment was caried out with 56 lines and 34 hybrids which were extracted from material corn and forage crop department were planted in Gharakhil agricultural research station in 2010-2011. Inter row space was 75 centimeters, row legth was 2/5 m and pland distance in row was 25 centimrters. By using artifical inoculation, all of gonotyps were inoculated by using scale rating, the rate of resistance was indentfied (Diseas severity) and the result in2010 showed that three lines were very suseptible, 11 lins were susceptible and others were tolorant. Two hybrids were susceptibl and others tolorant. Results in 2011 showed that five lines were susceptibleand12 lines were very tolorant. Hybrid, KE77007/14 × KE1264/5-1 was resistant, 31 hybrids were tolorant and one hybrid was susceptibl.