Journal of General Plant Pathology

, Volume 67, Issue 2, pp 97–105

Construction and Genetic Analysis of Hybrid Strains between Apple and Tomato Pathotypes of Alternaria alternata by Protoplast Fusion

  •  SALAMIAH
  • Hajime AKAMATSU
  • Yukitaka FUKUMASA-NAKAI
  • Hiroshi OTANI
  • Motoichiro KODAMA

The genetic controls of host-specific toxin (HST) biosynthesis and the pathogenicity of A. alternata pathogens have been limited by the asexual nature of the life cycle of these fungi. We used a protoplast fusion system for A. alternata to analyze the genetics of HST production and its relation to the specific pathogenicity of these pathogens. Drug-resistant transformants were isolated by genetic transformation, using vectors conferring resistance to hygromycin B and geneticin, for the A. alternata apple pathotype (AM-toxin producer) and A. alternata tomato pathotype (AAL-toxin producer), respectively. Protoplasts of the respective transformants were fused by electrofusion. The majority of resultant stable fusants produced both AM- and AAL-toxins and were pathogenic to susceptible cultivars of both apple and tomato. Pulsed-field gel electrophoresis analysis demonstrated that these fusants (or hybrids) carried small 1.7-and 1.1-Mb chromosomes, characteristic of the parental strains of the apple and tomato pathotypes, respectively. Detection of the AMT gene, involved in AM-toxin biosynthesis, by polymerase chain reaction revealed that all fusants pathogenic to apple maintained this gene. Microfluorimetry analysis using propidium iodide staining suggested that the fusants might be diploid.

Key words : Alternaria alternata, AM-toxin, AAL-toxin, protoplast fusion. 

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Copyright information

© The Phytopathological Society of Japan 2001

Authors and Affiliations

  •  SALAMIAH
    • 1
  • Hajime AKAMATSU
    • 1
  • Yukitaka FUKUMASA-NAKAI
    • 2
  • Hiroshi OTANI
    • 1
  • Motoichiro KODAMA
    • 1
  1. 1.Faculty of Agriculture, Tottori University, Koyama, Tottori 680–8553, JapanJP
  2. 2.The Tottori Mycological Institute, Kokoge, Tottori 689–1125, JapanJP

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