Analysis of mitochondrial genetic diversity of Ustilago maydis in Mexico

Abstract

The current understanding of the genetic diversity of the phytopathogenic fungus Ustilago maydis is limited. To determine the genetic diversity and structure of U. maydis, 48 fungal isolates were analyzed using mitochondrial simple sequence repeats (SSRs). Tumours (corn smut or ‘huitlacoche’) were collected from different Mexican states with diverse environmental conditions. Using bioinformatic tools, five microsatellites were identified within intergenic regions of the U. maydis mitochondrial genome. SSRMUM4 was the most polymorphic marker. The most common repeats were hexanucleotides. A total of 12 allelic variants were identified, with a mean of 2.4 alleles per locus. An estimate of the genetic diversity using analysis of molecular variance (AMOVA) revealed that the highest variance component is within states (84%), with moderate genetic differentiation between states (16%) (F_ST= 0.158). A dendrogram generated using the unweighted paired-grouping method with arithmetic averages (UPGMA) and the Bayesian analysis of population structure grouped the U. maydis isolates into two subgroups (K = 2) based on their shared SSRs.

Keywords:

• Basidiomycete
• genetic diversity
• mitochondrial SSR
• plant pathogen

Disclosure statement

The authors report no conflict of interest. JMGP and MSO are National Investigators, SNI, Mexico.

Additional information

Funding

This work was supported by 20090636 and 20100524 SIP-IPN grants and partially by 84557 CONACYT grant. JMGP, SHD, MSO are supported by COFAA and EDI-IPN.