Potential Yield Reductions in Maize Associated with an Anthracnose/European Corn Borer Pest Complex in New York

Keller, Nancy P.; Bergstrom, Gary C.; Carruthers, R. I.

doi:10.1094/phyto-76-586

Cited by 41 publications

(42 citation statements)

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“…Not surprisingly, O. nubilalis damage is highly associated with stalk rot pathogens, including Colletotrichum graminicola and Fusarium spp. (10,11). Keller et al (11) summarized this relationship, stating that "Consequently, any yield reduction studies, breeding programs, or other control strategies focusing on a single fungus or insect would be incomplete without detailed consideration of the concomitant role of other pests."…”

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confidence: 99%

“…(10,11). Keller et al (11) summarized this relationship, stating that "Consequently, any yield reduction studies, breeding programs, or other control strategies focusing on a single fungus or insect would be incomplete without detailed consideration of the concomitant role of other pests." The elucidation of maize defense mechanisms remains a topic of significant interest, given that the combined pressures of O. nubilalis and stalk rot pathogens have resulted in $1 billion annual losses in US production alone (12,13).…”

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confidence: 99%

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Identity, regulation, and activity of inducible diterpenoid phytoalexins in maize

Schmelz

Kaplan

Huffaker

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

236

281

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Phytoalexins constitute a broad category of pathogen-and insectinducible biochemicals that locally protect plant tissues. Because of their agronomic significance, maize and rice have been extensively investigated for their terpenoid-based defenses, which include insect-inducible monoterpene and sesquiterpene volatiles. Rice also produces a complex array of pathogen-inducible diterpenoid phytoalexins. Despite the demonstration of fungal-induced entkaur-15-ene production in maize over 30 y ago, the identity of functionally analogous maize diterpenoid phytoalexins has remained elusive. In response to stem attack by the European corn borer (Ostrinia nubilalis) and fungi, we observed the induced accumulation of six ent-kaurane-related diterpenoids, collectively termed kauralexins. Isolation and identification of the predominant Rhizopus microsporus-induced metabolites revealed ent-kaur-19-al-17-oic acid and the unique analog ent-kaur-15-en-19-al-17-oic acid, assigned as kauralexins A3 and B3, respectively. Encoding an entcopalyl diphosphate synthase, fungal-induced An2 transcript accumulation precedes highly localized kauralexin production, which can eventually exceed 100 μg·g −1 fresh weight. Pharmacological applications of jasmonic acid and ethylene also synergize the induced accumulation of kauralexins. Occurring at elevated levels in the scutella of all inbred lines examined, kauralexins appear ubiquitous in maize. At concentrations as low as 10 μg·mL −1 , kauralexin B3 significantly inhibited the growth of the opportunistic necrotroph R. microsporus and the causal agent of anthracnose stalk rot, Colletotrichum graminicola. Kauralexins also exhibited significant O. nubilalis antifeedant activity. Our work establishes the presence of diterpenoid defenses in maize and enables a more detailed analysis of their biosynthetic pathways, regulation, and crop defense function.

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confidence: 99%

mentioning

confidence: 99%

Identity, regulation, and activity of inducible diterpenoid phytoalexins in maize

Schmelz

Kaplan

Huffaker

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

236

281

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“…The disease can affect most plant tissues, though the stalk rot and seedling blight forms of the disease are the most economically damaging. It has become recognized as one of the predominant stalk rot pathogens of maize in North America during the past few decades (28,32,39). During the leaf blight form of the disease (anthracnose leaf blight [ALB]), visible lesions form first on the lower leaves and progressively move upward as the plant matures (27,33).…”

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Root Infection and Systemic Colonization of Maize byColletotrichum graminicola

Sukno

García

Shaw

et al. 2008

Appl Environ Microbiol

109

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Colletotrichum graminicola is a filamentous ascomycete that causes anthracnose disease of maize. While the fungus can cause devastating foliar leaf blight and stalk rot diseases, little is known about its ability to infect roots. Previously published reports suggest that C. graminicola may infect maize roots and that root infections may contribute to the colonization of aboveground plant tissues, leading to disease. To determine whether C. graminicola can infect maize roots and whether root infections can result in the colonization of aboveground plant tissues, we developed a green fluorescent protein-tagged strain and used it to study the plant root colonization and infection process in vivo. We observed structures produced by other root pathogenic fungi, including runner hyphae, hyphopodia, and microsclerotia. A mosaic pattern of infection resulted from specific epidermal and cortical cells becoming infected by intercellular hyphae while surrounding cells were uninfected, a pattern that is distinctly different from that described for leaves. Interestingly, falcate conidia, normally restricted to acervuli, were also found filling epidermal cells and root hairs. Twenty-eight percent of plants challenged with soilborne inoculum became infected in aboveground plant parts (stem and/or leaves), indicating that root infection can lead to asymptomatic systemic colonization of the plants. Many of the traits observed for C. graminicola have been previously reported for other root-pathogenic fungi, suggesting that these traits are evolutionally conserved in multiple fungal lineages. These observations suggest that root infection may be an important component of the maize anthracnose disease cycle.

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“…By tunneling through stalk tissue, they create entry points for fungal invasion, serve as vectors of some fungal pathogens, and cause physiological stress that can predispose maize plants to stalk rot development (3,6,7,12,26). This relationship between ECB damage and stalk rot is an important factor in pest management decision making, because the yield loss attributed to ECBs often is due in part to subsequent fungal decay of tissue injured by the larvae (7,13).…”

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A Comparison of Maize Stalk Rot Occurrence in Bt and Non-Bt Hybrids

2002

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Stalk rots, caused by a complex of fungal species, are among the most widespread and destructive diseases of maize. Larvae of the European corn borer (ECB) (Ostrinia nubilalis) promote stalk rot development by creating entry points for fungi, serving as vectors of pathogens, and causing physiological stress that may predispose plants to stalk decay. Field experiments were conducted in 1998, 1999, and 2000 to determine whether the use of transgenic Bt hybrids expressing insecticidal proteins would influence stalk rot symptoms (pith disintegration, pith discoloration, and lodging). Five hybrids representing different Bt types (or "Bt events") (176, BT11, MON810, DBT418, and CBH351) were paired with their near-isogenic, non-Bt counterparts and subjected to treatments of manual and natural infestation with ECB larvae. Manual infestation resulted in significantly more ECB tunneling than natural infestation in 1998 and 1999 and significantly more lodging in 1998. There were significant linear correlations between ECB injury and stalk rot symptoms in non-Bt hybrids in 1998 and 1999, but not in 2000. A standard foliar insecticide treatment for ECB did not significantly affect stalk rot symptoms. In 1998, Bt hybrids had significantly less ECB tunneling, stalk discoloration, pith disintegration, and lodging compared with non-Bt hybrids, but these effects depended upon the Bt event and the infestation treatment. Similar but less pronounced effects of Bt events were observed in 1999. The 2000 results were more variable; the amount of pith disintegration was significantly lower but discoloration was significantly higher in the BT11 hybrid compared with its non-Bt counterpart, and the amount of lodging was significantly higher in the event 176 hybrid compared with its non-Bt counterpart. The ratio of stalk strength to grain weight did not consistently differ between Bt and nonBt hybrids. These results indicate that, although specific Bt events in some years may cause reductions in stalk rot, the overall effect of Bt transformation on stalk rot occurrence is highly variable. Stalk rot is one of the most persistent and destructive diseases of maize throughout the world. The stalk rot complex comprises several fungal pathogens and secondary colonizers (15). The most common stalk rot pathogens in the United States include Gibberella zeae (Schwein.) Petch, Colletotrichum graminicola (Ces.) G. W. Wils., and Fusarium verticillioides (Sacc.) Nirenberg (16,27). Losses in the form of reduced grain-fill and premature death can occur when these pathogens invade maize stalks prior to physiological maturity (15).Destruction of the pith tissue also predisposes the plants to lodging.Stalk rot fungi overwinter in infected plant residue and invade maize plants through natural entry points such as nodes, through wounds created by insects or mechanical damage, or by direct penetration of root and stalk tissue (1,9,14,15,26). Plants are predisposed to stalk rot by any stress that reduces the photosynthetic capacity of the plant followin...

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Potential Yield Reductions in Maize Associated with an Anthracnose/European Corn Borer Pest Complex in New York

Cited by 41 publications

References 0 publications

Identity, regulation, and activity of inducible diterpenoid phytoalexins in maize

Identity, regulation, and activity of inducible diterpenoid phytoalexins in maize

Root Infection and Systemic Colonization of Maize byColletotrichum graminicola

A Comparison of Maize Stalk Rot Occurrence in Bt and Non-Bt Hybrids

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