Exploring the relationship between pattern-triggered immunity and quantitative resistance to Xanthomonas vasicola pv. vasculorum in maize

Bacterial leaf streak (BLS) of maize is an emerging foliar disease of maize in the Americas. It is caused by the gram-negative non-vascular bacterium Xanthomonas vasicola pv. vasculorum (Xvv). There are no chemical controls available for BLS, and thus, host resistance is crucial for managing Xvv. The objective of this study was to examine the genetic determinants of resistance to Xvv in maize, as well as the relationship between other defense-related traits and BLS resistance. Specifically, we examined the correlations among BLS severity, severity for three fungal diseases, flg-22 response, hypersensitive response and auricle color. We conducted quantitative trait locus (QTL) mapping for Xvv resistance using the maize recombinant inbred line population Z003 (B73 × CML228). We detected three QTL for BLS resistance. In addition to the disease resistance QTL, we detected a single QTL for auricle color. We observed significant, yet weak, correlations among BLS severity, levels of pattern-triggered immunity (PTI) response and leaf flecking. These results will be useful for understanding resistance to Xvv and mitigating the impact of BLS on maize yields.