Identification of QTL for target leaf spot resistance in Sorghum bicolor and investigation of relationships between disease resistance and variation in the MAMP response

Authors: KIMBALL, JENNIFER - University Of Minnesota; CUI, YAYA - University Of Missouri; CHEN, DONGQIN - University Of Missouri; BROWN, PAT - University Of California; ROONEY, WILLIAM - Texas A&M University; STACEY, GARY - University Of Missouri; Balint-Kurti, Peter

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2019
Publication Date: 12/4/2019
Citation: Kimball, J., Cui, Y., Chen, D., Brown, P., Rooney, W., Stacey, G., Balint Kurti, P.J. 2019. Identification of QTL for target leaf spot resistance in Sorghum bicolor and investigation of relationships between disease resistance and variation in the MAMP response. Scientific Reports. 9:1-9.

Interpretive Summary: We identified several places in the sorghum genome that contained genes conferring resistance to the fungal leaf disease target leaf spot. We also measured variation in the basal defense response of sorghum and examined its relationship to target leaf spot resistance. We did not find any evidence that variation in the basal defense response was responsible for variation in target leaf spot resistance.

Technical Abstract: 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 RIL 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 patterns (MAMPs) flg22 (a derivative of flagellin) and chitooctaose (a derivative of chitin). Flg22-induce ROS production varied between lines while results using chitooctaose were inconsistent. 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