Chromosome-length polymorphism in fungi

Area of Science:

• * Genetics and Genomics
• * Mycology
• * Molecular Biology

Background:

• * Fungal chromosomes exhibit significant length variation across species.
• * Pulsed-field gel electrophoresis (PFGE) is a key technique for analyzing large DNA molecules like fungal chromosomes.
• * Chromosome length polymorphism (CLP) is a widespread phenomenon in fungi.

Purpose of the Study:

• * To review the characteristics of fungal chromosome-length polymorphism.
• * To explore potential mechanisms driving chromosome length changes during mitosis and meiosis.
• * To discuss the implications of CLP for fungal karyotype diversity and adaptation.

Main Methods:

• * Review of existing literature on fungal chromosome analysis using pulsed-field gel electrophoresis.
• * Analysis of reported instances of chromosome length variation in both sexual and asexual fungi.
• * Examination of proposed molecular mechanisms for chromosome length alteration.

Main Results:

• * Widespread chromosome length polymorphism observed in both sexual and asexual fungal species.
• * Long tandem repeats, particularly rRNA gene tracts, are frequently identified as sources of length variation.
• * Other chromosomal rearrangements are generally suppressed during mitotic growth, with exceptions for dispensable chromosomes/regions.
• * Meiotic recombination contributes to karyotypic variability in sexual species while suppressing translocations.

Conclusions:

• * Fungal CLP is a significant source of karyotypic diversity.
• * Mechanisms like tandem repeat expansion/contraction and dispensable chromosomes contribute to CLP.
• * Genetic changes underlying CLP may be neutral or advantageous for fungal adaptation to new environments.