Antifungal Proteins and Other Mechanisms in the Control of Sorghum Stalk Rot and Grain Mold

Cereal Quality Laboratory, Texas A&M University, College Station, Texas 77843-2474, USA.
Journal of Agricultural and Food Chemistry (Impact Factor: 2.91). 11/2001; 49(10):4732-42. DOI: 10.1021/jf010007f
Source: PubMed


Research on antifungal proteins and other mechanisms that provide the biochemical basis for host-plant resistance to stalk rot and grain molds is reviewed in this paper. Stalk rot caused by Fusarium species leads to substantial yield loss due to poor grain filling and/or lodging. A transgenic sorghum expressing high levels of chitinase exhibited less stalk rot development when exposed to conidia of F. thapsinum. Grain mold of sorghum is associated with warm humid environments and results from colonization by several fungi (F. thapsinum, Curvularia lunata, and Alternaria alternata) of the developing caryopsis. The roles of several biochemical mechanisms (tannins, phenolic compounds, red pericarp, proteins, hard endosperm, and antifungal proteins) on grain mold resistance are discussed. Resistance mechanisms related to these compounds appear to be additive, and pyramiding of genes is a feasible approach to limit grain deterioration. Several experimental approaches are proposed to extend current findings.

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Available from: Arun Chandrashekar, Mar 08, 2014
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    • "practices, host plant resistance and/or tolerance to these stresses have been widely recognized as the most viable approach to enhancing productivity under these conditions (Waniska et al. 2001). Stalk rots are among the most important diseases of sorghum worldwide. "
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    ABSTRACT: Stalk rots are important biotic constraints to sorghum production worldwide. Several pathogens may be associated with the disease, but Macrophomina phaseolina and Fusarium thapsinum are recognized as the major causal organisms. The diseases become more aggressive when drought and high-temperature stress occur during grain filling. Progress in genetic improvement efforts has been slow due to lack of effective phenotyping protocol and the strong environmental effect on disease incidence and severity. Deployment of modern molecular tools is expected to accelerate efforts to develop resistant hybrids. This study was aimed at identifying genomic regions associated with resistance to both causal organisms. A sorghum diversity panel consisting of 300 genotypes assembled from different parts of the world was evaluated for response to infection by both pathogens. Community resources of 79,132 single nucleotide polymorphic (SNP) markers developed on the panel were used in association studies using a multi-locus mixed model to map loci associated with stalk rot resistance. Adequate genetic variation was observed for resistance to both pathogens. Structure analysis grouped the genotypes into five subpopulations primarily based on the racial category of the genotypes. Fourteen loci and a set of candidate genes appear to be involved in connected functions controlling plant defense response. However, each associated SNP had relatively small effect on the traits, accounting for 19-30% of phenotypic variation. Linkage disequilibrium analyses suggest that significant SNPs are genetically independent. Estimation of frequencies of associated alleles revealed that durra and caudatum subpopulations were enriched for resistant alleles, but the results suggest complex molecular mechanisms underlying resistance to both pathogens.
    Full-text · Article · Jun 2015 · G3-Genes Genomes Genetics
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    • "Many of these proteins, when expressed showed increased tolerance to fungal infection (Ulaganathan et al., 2001, 2003). Many antifungal proteins have been isolated from and characterized from sorghum seeds (Gosh and Ulaganathan, 1996, 2004, Waniska et al., 2001, Seetharaman et al., 1996; Bueso et al., 2000; Prom et al., 2005). Many of the antifungal proteins isolated from sorghum seeds have shown toxicity towards grain mold fungi but it is difficult to "

    Full-text · Chapter · Jan 2011
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    • "This study indicated that percentage of Pseudomonas isolates producing HCN increased through cycling of seedlings while those with phl declined except for those associated with soil planted with Redlan, in which an increase in percent of isolates with this trait was observed (Funnell-Harris et al. 2008). Herein we examined the effect of sorghum genotypes on populations of root-associated and soil fluorescent Pseudomonas spp., Fusarium spp., and another fungal genus, Alternaria, which also includes species pathogenic to sorghum (Waniska et al. 2001). No reports of numbers or characteristics of fluorescent Pseudomonas spp. in rhizospheres of differing sorghum genotypes, grown in different soils, are presently known. "
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    ABSTRACT: Sorghum [Sorghum bicolor (L.) Moench] is valued for bioenergy, feed and food. Potential of sorghum genotypes to support differing populations of root- and soil-associated fluorescent Pseudomonas spp. or Fusarium spp., in two soils, was assessed. Culturable pseudomonads were enumerated from roots and soil of sorghum (Redlan and RTx433) and wheat (Lewjain) seedlings repeatedly grown in cycled soils in the growth chamber. Pseudomonads and Fusarium spp. were assessed from roots and soil of field-grown sorghum along with biological control traits hydrogen cyanide (HCN) and 2,4-diacetylphlorogluconol (phl) production. After four 4-week cycles, soil associated with Redlan seedlings had greater numbers of fluorescent pseudomonads than Lewjain. In dryland field conditions, RTx433 roots had greater numbers of pseudomonads than Redlan before anthesis but similar numbers after. There were no differences in numbers of pseudomonads from dryland soil or roots or soil of irrigated plants. Percentages of HCN-producing root isolates and phl soil isolates declined on irrigated Redlan plants, but percentages of HCN-producers increased in dryland conditions. Redlan roots had greater percentages of Fusarium isolates in the Gibberella fujikuroi complex. Results indicated that sorghum genotype affected root-associated populations of fluorescent Pseudomonas spp. and Fusarium spp. across soil environments.
    Preview · Article · Oct 2010 · Plant and Soil
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