Response of sorghum accessions against newly documented pathotypes 5 and 6 of head smut pathogen, Sporisorium reilianum

Authors: Prom, Louis; PERUMAL, RAMASAMY - Kansas State University; ISAKEIT, THOMAS - Texas A&M University; ERATTAIMUTHU, SARADHA - Texas A&M University; MAGILL, CLINT - Texas A&M University

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2021
Publication Date: 3/31/2021
Citation: Prom, L.K., Perumal, R., Isakeit, T., Erattaimuthu, S., Magill, C. 2021. Response of sorghum accessions against newly documented pathotypes 5 and 6 of head smut pathogen, Sporisorium reilianum. American Journal of Plant Sciences. 12:432-443. https://doi.org/10.4236/ajps.2021.123028.
DOI: https://doi.org/10.4236/ajps.2021.123028

Interpretive Summary: Sorghum head smut is an important fungal disease and when susceptible cultivars/hybrids are planted, yield losses of up to 80% can occur. The use of resistant sources is the only effective means to control the disease. To identify resistant sources, sorghum accessions were evaluated against the two newly documented races of the head smut pathogen. The results showed that 18 accessions were resistant to both races. This work is significant because these resistant sources can be used to develop new breeding parental lines and hybrids for producers and the sorghum industry in the U.S. and abroad.

Technical Abstract: This study was conducted to identify resistance sources against the newly documented pathotypes (P5 and P6) of Sporisorium reilianum, causing sorghum head smut. A part of 63 sorghum association panel (SAP) accessions with checks BTx635 (resistant) and BTx643 (susceptible) were screened for two years 2017 and 2018 in the greenhouse. Each line was planted in 3-gallon pots replicated three times using a randomized complete design. At 18 to 20 days after planting, 61 and 40 accessions were respectively inoculated with P5 and P6 new pathotypes, by injecting the seedlings below the apical meristem with sporidial suspensions. Out of the 61 accessions challenged with P5, 62% were resistant, whereas 82% of the 40 accessions inoculated with P6 exhibited resistance to S. reilianum. Out of 38 accessions inoculated separately with P5 and P6, eighteen accessions, including PI533927, PI534075, PI534123, PI534135, PI534145, and PI651492 were resistance to both pathotypes. Among the 38 accessions inoculated with both pathotypes separately, eleven accessions including PI533965, PI533976, PI598069, PI642998 (Black Spanish), and PI656090 were resistant when challenged with P6 but susceptible to P5, while PI656015 and PI656033 were resistant to P5 but susceptible to P6 pathotypes. SAP accessions identified as new sources of resistance to pathotypes P5 and P6 of S. reilianum can be further used to develop new breeding parental lines and hybrids and mapping population for quantitative trait loci markers development closely linked to head smut resistance.