Target leaf spot (TLS) of sorghum, a foliar disease caused by the necrotrophic fungus Bipolaris cookei (also known as Bipolaris sorghicola), can affect grain yield in sorghum by causing premature drying of leaves and defoliation. Two sorghum recombinant inbred line (RIL) populations, BTx623/BTx642 and BTx623/SC155-14E, were assessed for TLS resistance in replicated trials. Using least square mean trait data, four TLS resistance QTL were identified, two in each population. Of these, three were previously unidentified while a major QTL on chromosome 5 in the BTx623/BTx642 RIL population corresponded to the previously identified TLS resistance gene ds1. A set of sorghum lines were assessed for production of reactive oxygen species induced by treatment with the microbe-associated molecular pattern (MAMP) flg22 (a derivative of flagellin). Flg22-induced ROS production varied between lines in a consistent fashion. One QTL associated with variation in the flg22 response was detected in the RIL populations. No evidence was found to link variation in the MAMP response to variation in TLS resistance.
Bibliographical noteFunding Information:
We thank Drs. Steve Kresovich for provision of sorghum lines and advice on seed handling and agronomic practice, Dr. Patricia Klein for genotypic data of the Btx623/SC155-14E RIL populations and Dr Burt Bluhm for providing isolates of B. cookei and for general advice. We thank Cathy Herring and the staff at Central Crops Research Station for their work facilitating the field trials. Dr. Shannon Sermons and Greg Marshall assisted with several aspects of the field research. This work was funded by the DOE Plant Feedstock Genomics for Bioenergy program grant #DE-SC0014116.
© 2019, The Author(s).