Biological and Molecular Variability of Sarocladium oryzae, the Sheath Rot Pathogen of Rice (Oryza sativa L.)

Abstract

Sheath rot disease of rice caused by Sarocladium oryzae (Sawada) (=Acrocylindrium oryzae, Sawada) has become an important production constraint in all rice-growing countries. Pathogenicity, phytotoxic metabolites, and random amplified polymorphic DNA (RAPD) markers were used to assess the level of genetic variability of S. oryzae derived from rice cultivars, CR1018, IR36, and IR50, of different locations in North East and South India. Variability in pathogenicity, phytotoxic metabolite production, and DNA polymorphisms was detected among S. oryzae isolates. Results indicated that S. oryzae isolates produced both cerulenin and helvolic acid at concentrations 0.3-0.62 and 0.9-4.8 microg mL(-1) of culture filtrate, respectively. Isolates that produce higher concentration of helvolic acid induced a high percent incidence of sheath rot disease. Oligonucleotide primers, GF and MR, generated either a simple (up to 2 bands) or complex (up to 6 bands) RAPD pattern. According to their level of similarity, S. oryzae isolates from North East and South India were grouped separately into two major clusters and 13 genotypes. Molecular- and pathogenicity-based classifications were not correlated, but a high level of genetic variability within S. oryzae isolates was identified. The molecular variability of S. oryzae isolates will be an important consideration in breeding programs to develop durable resistance for sheath rot disease.

The DinB Superfamily Includes Novel Mycothiol, Bacillithiol, and Glutathione S-Transferases

“…This suggests that BSH alone, or complexed with a suitable metal ((31) and unpublished results), may function together with a bacillithiol disulfide reductase (currently unidentified) to protect B. subtilis against peroxide toxicity. BsBST, but neither MsMST or EfGST, exhibited significant activity with the antibiotic cerulenin produced by the fungus Sarocladium oryzae (46). Other antibiotics, including antimycin A, azithromycin, lincomycin, spectinomycin and streptozocin, had little or no detectable activity (<2 nmol min -1 mg -1 ) with the three S -transferases in the thiol depletion assay.…”

Agro-ecological variations of sheath rot disease of rice caused by Sarocladium oryzae and DNA fingerprinting of the pathogen’s population structure

“…Variability among the population of S. oryzae has also been reported in India (Ayyadurai et al, 2005). Genetic variability among isolates collected from North East and South India, studied using VNTR with the GF and MR primers, revealed 2 major clusters.…”

“…Latif et al (2011 and successfully used VNTR with the GF, MR, and RY markers to examine the phylogenetic relationships among resistant and susceptible genotypes of rice blast, tungro, and ufra diseases. Development of durable disease-resistant varieties depends on pathogen variability (Ayyadurai et al, 2005;Miah et al, 2013). By understanding the population structure of S. oryzae, a plant breeder can enhance varietal development.…”

“…However, the development of durable, resistant varieties is necessary for understanding the pathogen population, particularly regarding genetic and pathogenic variability. Ayyadurai et al (2005) reported the genotypic variability of S. oryzae among isolates collected from North East and South India. Differences in the virulence among some isolates of S. oryzae were also observed in India (Yadav and Thrimurty, 2006).…”

Gliotoxin in Aspergillus fumigatus: an example that mycotoxins are potential virulence factors

“…S. oryzae isolates produce the mycotoxins cerulenin and helvolic acid. Isolates that produced higher concentrations of helvolic acid induced a higher percentage incidence of sheath rot disease (Ayyadurai et al 2005). Botrytis cinerea, a necrotrophic plant pathogen, is responsible for gray mold disease on more than 200 host plants.…”