Response of Sorghum Accessions against Newly Documented Pathotypes 5 and 6 of Head Smut Pathogen, <i>Sporisorium reilianum</i>

This study was conducted to identify resistance sources against the newly documented pathotypes (P5 and P6) of Sporisorium reilianum, causing sorghum head smut. A subset of 67 sorghum association panel (SAP) accessions, 29 in 2017 and 38 in 2018 along with checks BTx635 (resistant) and BTx643 (susceptible) were screened in the greenhouse against P5 and P6 pathotypes in two separate experiments in both years. At 18 to 20 days after planting, accessions were inoculated by injecting the seedlings below the apical meristem with sporidial suspensions following an established inoculation procedure. Three accessions (PI656091, PI533919, and PI533821) in 2017 and 17 accessions (PI597961, PI656071, PI656048, PI576435, PI534075, PI534145, PI656057, PI576437, PI651492, PI656014, PI656025, PI655999, PI656010, PI656082, PI534123, PI533927, PI656100) in 2018 were identified as potential resistant sources to both P5 and P6 pathotypes of S. reilianum. These SAP accessions are new sources that can be further used to develop new breeding parental lines and hybrids and mapping populations for quantitative trait loci markers closely linked to head smut resistance.