Parthenium hysterophorus L. is a novel source of resistance to Cicer arietinum L. dry root rot pathogen Macrophomina phaseolina (Tassi) Goid.

Dry root rot (DRR) disease of chickpea (Cicer arietinum L.) is caused by the broad range necrotrophic fungus, Macrophomina phaseolina (Tassi) Goid. The host germplasm does not provide durable resistance to DRR disease. Furthermore, the disease is particularly devastating under concurrent drought. Even moderately resistant C. arietinum varieties become susceptible under combined stress. We hypothesized that nonhost resistance (NHR) could be durable even under combined stress. In this study, we screened 12 potential nonhost species via the blotter paper assay. We show that Parthenium hysterophorus L., an Asterid weed exhibits NHR to M. phaseolina. Results from confocal microscopy show that mycelia of M. phaseolina is unable to infect the root cortex and did not form microsclerotia within the nonhost root cortical and vascular tissue and stereomicroscopy [Ma1] . Further, our results indicate that in this particular case, NHR is durable even under combined stress. We employed transcriptomic and metabolomic tools to elucidate the putative molecular mechanisms involved in NHR. We found that xyz mechanisms to be a part of the NHR phenomenon. This study highlights the fact that NHR is a robust alternative in situations when host resistance falters. We conclude that P. hysterophorus exhibits post-invasive (Type-II) [Ma2] NHR to M. phaseolina via the xyz pathway.[Ma3]