IAA-Mediated Haustorium Formation in Phelipanche aegyptiaca: Transcriptional Insights and Anti-Parasitic Strategies

<i>Phelipanche aegyptiaca</i> is an obligate root-parasitic weed that parasitizes crop roots, threatening the safety of agricultural production. However, the molecular mechanisms underlying the formation of <i>P. aegyptiaca</i> haustorium remain largely unclear. Here, we employed transcriptomics to investigate the molecular events in <i>P. aegyptiaca</i> haustorium formation induced by indole-3-acetic acid. Our study revealed that during <i>P. aegyptiaca</i> haustorium formation, the cell proliferation activity at the tip of the radicle was highest during the young stage and then gradually declined. The differentially expressed genes upregulated during haustorium formation were mainly enriched in DNA replication and plant hormone signal transduction, while those that were downregulated were enriched in biosynthesis of secondary metabolites. Additionally, interfering with the auxin signal weakened the parasitic ability of <i>P. aegyptiaca</i>. These findings enhance our understanding of the mechanism of <i>P. aegyptiaca</i> haustorium formation and contribute to the targeted development of new pesticides for inhibiting <i>P. aegyptiaca</i>.