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Mg-SINE: a short interspersed nuclear element from the rice blast fungus, Magnaporthe grisea
P Kachroo1, S A Leong, B B Chattoo
1Department of Microbiology, Faculty of Science, M. S. University of Baroda, India.
Abstract:
A short interspersed nuclear element, Mg-SINE, was isolated and characterized from the genome of the rice blast fungus, Magnaporthe grisea. Mg-SINE was isolated as an insertion element within Pot2, an inverted-repeat transposon from M. grisea and shows typical features of a mammalian SINE. Mg-SINE is present as a 0.47-kb interspersed sequence at approximately 100 copies per haploid genome in both rice and non-rice isolates of M. grisea, indicating a common evolutionary origin. Secondary structure analysis of Mg-SINE revealed a tRNA-related region at the 5' end which folds into a cloverleaf structure. Genomic fusions resulting in chimeric Mg-SINEs (Ch-SINEs) composed of a sequence homologous to Mg-SINE at the 3' end and an unrelated sequence at its 5' end were also isolated, indicating that this and other DNA rearrangements mediated by these elements may have a major effect on the genomic architecture of this fungus.
Insights
Researchers identified a novel short interspersed nuclear element (Mg-SINE) in the rice blast fungus Magnaporthe grisea. This element, present in multiple copies, shows unique structural features and influences the fungus's genome.
Area of Science:
- Genomics
- Molecular Biology
- Mycology
Background:
- The genome of Magnaporthe grisea, the rice blast fungus, contains various repetitive elements that influence its evolution and pathogenicity.
- Short interspersed nuclear elements (SINEs) are non-autonomous retrotransposons found across eukaryotic genomes, but their characterization in fungi is less extensive.
Purpose of the Study:
- To isolate and characterize a novel SINE element from Magnaporthe grisea.
- To investigate the structural features, genomic distribution, and potential impact of this element on the fungal genome.
Main Methods:
- Isolation and sequencing of the Mg-SINE element from Magnaporthe grisea.
- Bioinformatic analysis of Mg-SINE structure, including secondary structure prediction.
- Southern blot hybridization to determine copy number and distribution in different isolates.
- Identification and characterization of chimeric SINE elements (Ch-SINEs).
Main Results:
- A 0.47-kb interspersed nuclear element, designated Mg-SINE, was identified in Magnaporthe grisea.
- Mg-SINE exhibits characteristics typical of mammalian SINEs, including a tRNA-related region at the 5' end.
- The element is present at approximately 100 copies per haploid genome in both rice and non-rice isolates, suggesting a common origin.
- Genomic fusions led to chimeric Mg-SINEs (Ch-SINEs), indicating DNA rearrangements mediated by these elements.
Conclusions:
- Mg-SINE represents a novel class of SINE elements in the rice blast fungus.
- The presence and potential for rearrangement of Mg-SINE suggest a significant role in shaping the genomic architecture of Magnaporthe grisea.
- Further research into Mg-SINE and Ch-SINEs could provide insights into fungal genome evolution and plasticity.