PhD candidate University of California, Davis / Plant Biology
Cuscuta species (dodders) are common agriculturally destructive parasitic angiosperms and use haustoria as physiological bridges to extract nutrients and water from hosts. However, some Heinz tomato hybrid cultivars exhibit resistance to dodders. The stem cortex in these resistant lines responds with local lignification upon C. campestris attachment, preventing parasite entry into the host. We compared gene expression patterns under C. campestris infestation in resistant and susceptible cultivars and identified LIF1 (Lignin Induction Factor 1, an AP2-like transcription factor), SlMYB55, and CuRLR1 (Cuscuta R-gene for Lignin-based Resistance 1, a CC-NBS-LRR) as key factors conferring host resistance. Transient overexpression results suggest that SlMYB55 and LIF1 directly regulate cortical lignification. We also identified SlWRKY16 as a negative regulator of LIF1 function. Moreover, CuRLR1 may play a role in signaling or function as a receptor for receiving C. campestris signals to regulate lignification-based resistance. These results will aid in developing parasitic plant-resistant crops.
Coauthors: Neelima Sinha – Professor, Department of Plant Biology, University of California, Davis