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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Insect Control and Cotton Disease Research » Research » Publications at this Location » Publication #410091
Research Project: Molecular and Genetic Approaches to Manage Cotton and Sorghum Diseases

Location: Insect Control and Cotton Disease Research

Title: Genetic and pathogenic variability among isolates of Sporisorium reilianum causing sorghum head smut

Author
item Prom, Louis
item Ahn, Ezekiel
item PERUMAL, RAMASAMY - Kansas State University
item ISAKEIT, THOMAS - Texas A&M University
item ODVODY, GARY - Texas A&M University
item MAGILL, CLINT - Texas A&M University

Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2024
Publication Date: 1/12/2024
Citation: Prom, L.K., Ahn, E.J., Perumal, R., Isakeit, T.S., Odvody, G.N., Magill, C.W. 2024. Genetic and pathogenic variability among isolates of Sporisorium reilianum causing sorghum head smut. The Journal of Fungi. 10(1). Article 62. https://doi.org/10.3390/jof10010062.
DOI: https://doi.org/10.3390/jof10010062

Interpretive Summary: Head smut is an important fungal disease of sorghum that occurs in most production regions. Although resistant cultivars or hybrids exist, control of head smut can be difficult due to the occurrence of different strains within the pathogen population. In this study, we identified the strains of the pathogen that exist in Texas, and examined the genetic variation among strains. The work showed high genetic diversity among strains and revealed the occurrence of a new head smut strain in Texas. The existence of this new strain in Texas will require the screening of sorghum lines to identify resistant sources to this new strain before it becomes a problem for sorghum producers.

Technical Abstract: Sporisorium reilianum, the causal agent of sorghum (Sorghum bicolor (L.) Moench) head smut is present in most sorghum producing regions. This seed replacement fungal disease can reduce yield by up to 80% in severely infected fields. Management of this disease can be challenging due to the appearance of different pathotypes within the pathogenic population. In this research, the genetic variability and pathogenicity of isolates collected from five Texas Counties was conducted. The results revealed the occurrence of a new pathotype 1A and four previously documented US pathotypes when the 21 isolates were evaluated for virulence pattern against six sorghum differentials. The most prevalent was pathotype 5 which was recovered from Brazos, Hidalgo, Nueces, and Willacy Counties, Texas. This pathotype was followed by 1A and 6 in frequency of recovery. Pathotype 4 was identified only from isolates collected from Hidalgo County, while pathotype 1 was from Burleson County, Texas. It appeared that the previous US head smut pathotypes (2 and 3) are no longer common and the new pathotypes 1A, 5, and 6 are now predominant. The phylogenetic tree constructed from the single nucleotide polymorphisms (SNPs) data through the Maximum Likelihood method showed high genetic diversity among the tested isolates. Some of the diverse clades among the tested isolates were independent of their sampled locations. Notably, HS37, HS49 and HS65 formed a clade and were classified as 1A in the virulence study, while HS 61 and HS 66, which were collected from Nueces County, were grouped, and identified as pathotype 5.