Genotypic differences in the resistance of maize silk to<i>Fusarium graminearum</i>

Reid, L. M.; Mather, D. E.; Hamilton, R. I.; Bolton, A. T.

doi:10.1080/07060669209500877

Cited by 50 publications

(25 citation statements)

References 9 publications

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“…All ears were shoot-bagged prior to silk emergence to prevent pollination throughout the tissue collection period, except where noted. Primary ears were silk channel inoculated, 4-6 days post silk emergence (dpe), with a F. graminearum macroconidia suspension grown in Bilay's solution (Reid et al, 1992), at a concentration of 500,000 spores/ml. Mock (sterile Bilay's solution), F. verticillioides (500,000 spores/ml), F. subglutanins (500,000 spores/ ml) and salicylic acid (10 mM in dH 2 0) inoculations were conducted using the same technique as for Fg inoculations.…”

Section: Plant Materialsmentioning

confidence: 99%

The Maize An2 Gene is Induced by Fusarium Attack and Encodes an ent-Copalyl Diphosphate Synthase

et al. 2005

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Using the technique of differential display, a maize transcript was identified whose silk tissue expression is induced in the presence of the ear rot pathogen Fusarium graminearum. The 3445 nt transcript includes a 727 nt 5' untranslated leader with the potential for extensive secondary structure and represents the maize gene An2. An2 encodes a copalyl diphosphate synthase (CPS)-like protein with 60% amino acid sequence identity with the maize An1 gene product involved in gibberellin (GA) biosynthesis. Recombinant expression and functional analysis demonstrated that both AN1 and AN2 are ent-copalyl diphosphate (ent-CPP) synthases (ent-CPS). Notably, the presence of an additional ent-CPS gene is consistent with previous reports that maize GA biosynthesis can proceed in the absence of An1. In addition, northern blot analysis showed that An2 transcript levels were strongly up-regulated by Fusarium attack, with an increase in silk, husk and ear tip tissues as early as 6 h after inoculation of silk channels with spore suspensions of various Fusarium sp. Gene expression of a third maize CPS-like gene, Cpsl1, is not affected by Fusarium infection. The Fusarium-inducible nature of An2 is also consistent with a previous report that cell-free extracts from maize seedlings produce ent-CPP derived diterpenes in response to Fusarium infection. However, it is not known whether An2 is involved in defense-related secondary metabolism in addition to GA synthesis.

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Section: Plant Materialsmentioning

confidence: 99%

The Maize An2 Gene is Induced by Fusarium Attack and Encodes an ent-Copalyl Diphosphate Synthase

et al. 2005

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“…Ten primary ears of each hybrid were inoculated once per replicate, per inoculation method in each subplot, for each of the two pathogens. Silk inoculations were done at 50% silk browning (Reid et al 1992), while wound inoculations were done after 600 crop heat units (Brown and Bootsma 1993) accumulated post 50% silking, when kernels were most susceptible to wound infection (Schaafsma et al 1993;Reid et al 2002). The single inoculations were spread over 3 weeks to accommodate the range of hybrid maturities.…”

Section: Inoculum Preparation and Inoculationmentioning

confidence: 99%

Fumonisin B₁accumulation and severity of fusarium ear rot and gibberella ear rot in food-grade corn hybrids in Ontario after inoculation according to two methods

Schaafsma

Tamburic-Ilincic

Reid

2006

Canadian Journal of Plant Pathology

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Fusarium verticillioides and Fusarium graminearum are pathogens of corn causing fusarium ear rot and gibberella ear rot, respectively. The mycotoxins fumonisin B 1 (FB 1 ) and deoxynivalenol (DON) are produced by F. verticillioides and F. graminearum, respectively, and commercial millers monitor the levels of these toxins in corn to avoid problems with contamination in finished foods. The objectives of the present study were: (1) to evaluate the susceptibility of corn hybrids to F. graminearum and F. verticillioides, following silk-channel or kernel-wounding inoculations, (2) to evaluate the variability in FB 1 production among food-grade corn hybrids, following silk or wound inoculation with F. verticillioides, and (3) to determine the association between the severity of fusarium ear rot and FB 1 to see if visual ratings of fusarium ear rot are predictive of the tendency of corn hybrids to accumulate FB 1 . The experiments were conducted in the field from 1999 to 2002 with different sets of commercial hybrids each year. Mean fusarium ear rot severity and FB 1 accumulation varied among years regardless of the inoculation method. Severity of fusarium ear rot and gibberella ear rot (rating on a scale of 1-7) varied respectively from 1.5 to 2.7 and 1.8 to 3.9, with silk inoculation, and from 2.0 to 2.3 and 2.8 to 4.2, with wound inoculation. For a same inoculation method, hybrids responses differed between F. graminearum and F. verticillioides inoculations, likely influenced by the different environmental conditions favoured by each fungus. There was a high level of variation in FB 1 accumulation among the hybrids within each year; for example, FB 1 accumulation across hybrids grown under the same environmental conditions ranged from not detected to 211.2 ppm in 2001. Severity of fusarium ear rot and FB 1 accumulation after wound inoculation with F. verticillioides were correlated, suggesting that severity symptoms of fusarium ear rot after wound inoculation might be useful to select hybrids that are less likely to accumulate FB 1 . 557

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“…The objective of this study was to investigate the initiation and development of F. graminearum on silks of fertilized ears of maize, using microscopy. In our work, we have concentrated on infection via the silks because there is at least one mechanism of resistance to F. graminearum that is based in the silks (Reid et al 1992a(Reid et al , 1994Miller et al 2003). Both fungus-resistant and fungus-susceptible genotypes of maize were used in this study so that potential differences in the progression of the fungus could be observed.…”

Section: Introductionmentioning

confidence: 99%

Colonization of maize silks by Fusarium graminearum, the causative organism of gibberella ear rot

2007

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One of the most economically important diseases of maize in Canada is gibberella ear rot caused by Fusarium graminearum Schwabe (teleomorph = Gibberella zeae (Schw.) Petch). Understanding how the fungus becomes established will help in developing effective strategies to reduce the incidence of this disease. This study investigates the infection process of F. graminearum on maize silks using both a wild-type F. graminearum as well as a strain transformed with a gene from jellyfish to constitutively express green fluorescent protein. Immature ears of maize were inoculated in the field with wild-type F. graminearum and harvested at specific times post infection, and the silks were stained with Chlorazol Black E for examination. In addition, uninoculated ears were excised, placed on water agar in large Petri dishes, and the silks inoculated with a suspension of macroconidia of the transformed fungus. The progress of fungal growth was then monitored using microscopy. Germination of conidia was observed 4-6 h after inoculation. A variable period of random growth often followed, after which some of the hyphae would grow in more or less straight lines down the silk towards the cob (rachis), and ultimately infect the developing kernels. Access to the cob occurred in 7-9 d in susceptible genotypes and 12-15 d in resistant genotypes. The fungus could penetrate the ovary directly through the silk attachment point or, when the silk was growing over other kernels, the fungus could traverse from the silk to colonize interkernel spaces. Entry into the cob was either through the rachis surface via exterior growth between kernels, or into the rachis via the pedicel.Résumé : Une des plus importantes maladies du maïs au Canada est la fusariose des épis, causée par le Fusarium graminearum Schwabe (teleomorph = Gibberella zeae (Schw.) Petch). Une compréhension du processus d'établissement du champignon aiderait à développer des stratégies efficaces pour réduire l'incidence de cette maladie. Les auteurs ont entrepris cette étude pour examiner le processus d'infection des barbes du maïs par le F. graminearum, en utilisant à la fois un type sauvage du F. graminearum et une souche transformée avec un gène de méduse, afin d'exprimer constitutivement une protéine verte fluorescente (GFP). Ils ont inoculé de jeunes épis de maïs, aux champs, avec le type sauvage, les ont récoltés périodiquement, et ont coloré les barbes au noir de chlorazol E. De plus, ils ont prélevé des épis non-inoculés, les ont placés sur eau gélosée dans de grands Petri et en ont inoculé les barbes avec une suspension de macroconidies du champignon transformé. Ils ont par la suite suivi la progression de la croissance fongique au microscope. On observe la germination des conidies 4-6 heures après l'inoculation. Une période variable de croissance aléatoire suit l'infection et, par après, certains des hyphes poussent en lignes plus ou moins droites dans la barbe vers l'épi (rachis), pour ultimement infecter le grain en formation. L'accès à l'épi survient après 7-9 jours ch...

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Genotypic differences in the resistance of maize silk toFusarium graminearum

Cited by 50 publications

References 9 publications

The Maize An2 Gene is Induced by Fusarium Attack and Encodes an ent-Copalyl Diphosphate Synthase

The Maize An2 Gene is Induced by Fusarium Attack and Encodes an ent-Copalyl Diphosphate Synthase

Fumonisin B₁accumulation and severity of fusarium ear rot and gibberella ear rot in food-grade corn hybrids in Ontario after inoculation according to two methods

Colonization of maize silks by Fusarium graminearum, the causative organism of gibberella ear rot

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Genotypic differences in the resistance of maize silk toFusarium graminearum

Cited by 50 publications

References 9 publications

The Maize An2 Gene is Induced by Fusarium Attack and Encodes an ent-Copalyl Diphosphate Synthase

The Maize An2 Gene is Induced by Fusarium Attack and Encodes an ent-Copalyl Diphosphate Synthase

Fumonisin B1accumulation and severity of fusarium ear rot and gibberella ear rot in food-grade corn hybrids in Ontario after inoculation according to two methods

Colonization of maize silks by Fusarium graminearum, the causative organism of gibberella ear rot

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Product

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Fumonisin B₁accumulation and severity of fusarium ear rot and gibberella ear rot in food-grade corn hybrids in Ontario after inoculation according to two methods