Parasexual reproduction in Alternaria solani: Simple sequence repeat molecular evidence for haploidization

Area of Science:

• Mycology
• Molecular Biology
• Plant Pathology

Background:

• Alternaria solani, a significant plant pathogen, exhibits complex genetic behavior.
• Previous observations of multiple alleles and sectoring in A. solani suggested a potential parasexual cycle.
• The absence of documented sexual reproduction in A. solani necessitates investigation into alternative genetic recombination mechanisms.

Purpose of the Study:

• To investigate the potential parasexual cycle in Alternaria solani using molecular markers.
• To provide molecular evidence for parasexual reproduction in A. solani.
• To utilize simple sequence repeat (SSR) markers to track genetic changes during mitosis and parasexuality.

Main Methods:

• Codominant SSR markers were employed as molecular probes on A. solani chromosomes.
• Single-conidium subculturing was used to simulate natural mitotic processes.
• Allele dynamics at the As-95236 locus were monitored to identify haploidization events.

Main Results:

• The number of alleles at the As-95236 locus decreased from two to one, indicating haploidization.
• Testing of fifty monosporic F1 strains revealed allele loss in 38% of parent strains.
• Analysis of F2 strains showed a 75% probability of allele loss in all four F1 strains.

Conclusions:

• The observed allele loss in A. solani subcultures provides strong molecular evidence for parasexual reproduction.
• Parasexuality may play a significant role in the genetic variation and adaptation of A. solani.
• This study contributes to understanding the reproductive biology of a key agricultural pathogen.