Biology subjects

Spallek, T.

Publications and source records attributed to Spallek, T..

4 recordsLinked to original sources

bioRxiv2026

Virus-induced genome editing in the parasitic plant Phtheirospermum japonicum

Phtheirospermum japonicum is a genetic model for parasitic Orobanchaceae, a plant family that includes noxious parasitic weeds from the genera Striga, Orobanche, and Phelipanche (Ishida et al., 2011). Striga species alone cause billions of dollars in annual losses by reducing yields of major crops (Pennisi, 2010). The lack of stable transgenesis protocols often hinders heritable CRISPR/Cas9 genome editing for gene function analysis in crops and species beyond standard model plants, including parasitic Orobanchaceae (Steinberger and Voytas, 2025). Here, we adapted a virus-mediated delivery system for ultracompact TnpB nucleases, enabling genome editing independently of tissue regeneration or floral dip transformation in the parasitic plant P. japonicum (Nagalakshmi et al., 2025; Weiss et al., 2025).

plant biology↗

bioRxiv2026

The parasitic plant Phtheirospermum japonicum suppresses host immunity

The parasitic plant Phtheirospermum japonicum invades the host root xylem to extract nutrients and water. We show that this invasion triggers a phosphate-starvation response in its host, Arabidopsis thaliana, causing systemic suppression of immunity, including defence responses against microbial pathogens. Consequently, plants infested by xylem-feeding parasitic plants were more susceptible to secondary infections, underscoring the need to consider multitrophic interactions when improving crop resilience to parasitic infestation.

plant biology↗

bioRxiv2021

The Phtheirospermum japonicum isopentenyltransferase PjIPT1a regulates host cytokinin responses in Arabidopsis

The hemiparasitic plant Phtheirospermum japonicum is a nutritional specialist that supplements its nutrient requirements by parasitizing other plants through haustoria. During parasitism, the Phtheirospermum haustorium transfers hypertrophy-inducing cytokinins (CKs) to the infected host root. The CK biosynthesis genes required for haustorium-derived CKs and the induction of hypertrophy are still unknown. We searched for haustorium-expressed isopentenyltransferases (IPTs) that catalyse the first step of CK biosynthesis, confirmed the specific expression by in vivo imaging of a promoter-reporter, and further analysed the subcellular localization, the enzymatic function, and contribution to inducing hypertrophy by studying CRISPR-Cas9 induced Phtheirospermum mutants. PjIPT1a was expressed in intrusive cells of the haustorium close to the host vasculature. PjIPT1a and its closest homolog PjIPT1b located to the cytosol and showed isopentenyltransferases activity in vitro with differences in substrate specificity. Mutating PjIPT1a abolished parasite-induced CK responses in the host. A homolog of PjIPT1a with shared characteristics was also identified in the related weed Striga hermonthica. We propose that PjIPT1a exemplifies how parasitism-related functions evolve through gene duplications and neofunctionalization.

plant biology↗

bioRxiv2020

Subtilase activity in the intrusive cells mediates haustorium maturation in parasitic plants

Parasitic plants that infect crops are devastating to agriculture throughout the world. They develop a unique inducible organ called the haustorium, which connects the vascular systems of the parasite and host to establish a flow of water and nutrients. Upon contact with the host, the haustorial epidermal cells at the interface with the host differentiate into specific cells called intrusive cells that grow endophytically towards the host vasculature. Then, some of the intrusive cells re-differentiate to form a xylem bridge that connects the vasculatures of the parasite and host. Despite the prominent role of intrusive cells in host infection, the molecular mechanisms mediating parasitism in the intrusive cells are unknown. In this study, we investigated differential gene expression in the intrusive cells of the facultative parasite Phtheirospermum japonicum in the family Orobanchaceae by RNA-Sequencing of laser-microdissected haustoria. We then used promoter analyses to identify genes that are specifically induced in intrusive cells, and used promoter fusions with genes encoding fluorescent proteins to develop intrusive cell-specific markers. Four of the intrusive cell-specific genes encode subtilisin-like serine proteases (SBTs), whose biological functions in parasitic plants are unknown. Expression of an SBT inhibitor in the intrusive cells inhibited their development, inhibited the development of the xylem bridge, and reduced auxin response levels near the site where the xylem bridge normally develops. Therefore, we propose that subtilase activity plays an important role in haustorium development in this parasitic plant. One sentence summaryTissue-specific analysis showed that the subtilases specifically expressed in intrusive cells regulate auxin-mediated host-parasite connections in the parasitic plant Phtheirospermum japonicum.

plant biology↗