The hemiparasitic plant Phtheirospermum japonicum (Phtheirospermum) 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 catalyze the first step of CK biosynthesis, confirmed the specific expression by in vivo imaging of a promoter-reporter, and further analyzed 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 IPT activity in vitro with differences in substrate specificity. Mutating PjIPT1a abolished parasite-induced CK responses in the host. A homolog of PjIPT1a also was identified in the related weed Striga hermonthica. With PjIPT1a, we identified the IPT enzyme that induces CK responses in Phtheirospermum japonicum-infected Arabidopsis roots. We propose that PjIPT1a exemplifies how parasitism-related functions evolve through gene duplications and neofunctionalization.
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http://dx.doi.org/10.1111/nph.17615 | DOI Listing |
Proc Natl Acad Sci U S A
October 2024
Department of Plant Physiology and Biochemistry, University of Hohenheim, Stuttgart 70599, Germany.
Plant Cell Physiol
December 2024
Laboratory of Plant Chemical Regulation, School of Agriculture, Meiji University, 1-1-1 Higashi-Mita, Tama-ku, Kawasaki, Kanagawa, 214-8571 Japan.
Phtheirospermum japonicum, a member of the Orobanchaceae family, is a facultative root parasitic plant that can survive without parasitizing the host. In contrast, obligate root parasitic plants, such as Striga and Orobanche, which are also members of the Orobanchaceae family, cannot survive in the absence of the host. The germination of obligate root parasitic plants is typically induced by host root-derived strigolactones (SLs) at very low concentrations.
View Article and Find Full Text PDFPlant Cell Physiol
December 2024
Department of Botany and Plant Sciences, University of California, 3401 Watkins Drive, Riverside, CA 92521, USA.
Many root parasitic plants in the Orobanchaceae use host-derived strigolactones (SLs) as germination cues. This adaptation facilitates attachment to a host and is particularly important for the success of obligate parasitic weeds that cause substantial crop losses globally. Parasite seeds sense SLs through 'divergent' KARRIKIN INSENSITIVE2 (KAI2d)/HYPOSENSITIVE TO LIGHT α/β-hydrolases that have undergone substantial duplication and diversification in Orobanchaceae genomes.
View Article and Find Full Text PDFJ Plant Physiol
May 2024
Institute of Life and Environmental Sciences, School of Science and Technology, University of Tsukuba, Tennodai 1-1-1, Tsukuba, 305-8577, Japan. Electronic address:
While parasites are likely to connect to multiple host plants in nature, parasitism dynamics under multiple association conditions remain unclear and are difficult to separate from competitive effects. In this study, a five-compartment split root-box was constructed to allow a single facultative root hemiparasite, Phtheirospermum japonicum, to connect to zero, one or two Medicago sativa hosts while maintaining constant plant number and independently controlling nutrient supply. In the first experiment, we found that P.
View Article and Find Full Text PDFPlant Signal Behav
December 2023
Department of Botany, Panjab University, Chandigarh, India.
shows induced expression of and genes during haustoria development in rice and Arabidopsis with increased PME activity, which leads to the modulated cell wall during parasitism. Moreover, how PME and PMEI proteins interact and balance during haustoria development remains elusive.
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