title: The Role of Endogenous Strigolactones and Their Interaction with ABA during the Infection Process of the Parasitic WeedPhelipanche ramosain Tomato Plants.
abstract: The root parasitic plant speciesPhelipanche ramosa, branched broomrape, causes severe damage to economically important crops such as tomato. Its seed germination is triggered by host-derived signals upon which it invades the host root. In tomato, strigolactones (SLs) are the main germination stimulants forP. ramosa. Therefore, the development of low SL-producing lines may be an approach to combat the parasitic weed problem. However, since SLs are also a plant hormone controlling many aspects of plant development, SL deficiency may also have an effect on post-germination stages of the infection process, during the parasite-host interaction. In this study, we show that SL-deficient tomato plants (Solanum lycopersicum; SlCCD8RNAi lines), infected with pre-germinatedP. ramosaseeds, display an increased infection level and faster development of the parasite, which suggests a positive role for SLs in the host defense against parasitic plant invasion. Furthermore, we show that SL-deficient tomato plants lose their characteristic SL-deficient phenotype during an infection withP. ramosathrough a reduction in the number of internodes and the number and length of secondary branches. Infection withP. ramosaresulted in increased levels of abscisic acid (ABA) in the leaves and roots of both wild type and SL-deficient lines. Upon parasite infection, the level of the conjugate ABA-glucose ester (ABA-GE) also increased in leaves of both wild type and SL-deficient lines and in roots of one SL-deficient line. The uninfected SL-deficient lines had a higher leaf ABA-GE level than the wild type. Despite the high levels of ABA, stomatal aperture and water loss rate were not affected by parasite infection in the SL-deficient line, while in wild type tomato stomatal aperture and water loss increased upon infection. Future studies are needed to further underpin the role that SLs play in the interaction of hosts with parasitic plants and which other plant hormones interact with the SLs during this process.
authors.affiliation: Laboratory of Plant Physiology, Wageningen University Wageningen, Netherlands.
authors.forename: Xi
authors.initials: X
authors.lastname: Cheng
authors.affiliation: Laboratory of Plant Physiology, Wageningen UniversityWageningen, Netherlands; Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany AS CR and Faculty of Science, Palacký UniversityOlomouc, Czechia.
authors.forename: Kristýna
authors.initials: K
authors.lastname: Floková
authors.affiliation: Laboratory of Plant Physiology, Wageningen University Wageningen, Netherlands.
authors.forename: Harro
authors.initials: H
authors.lastname: Bouwmeester
authors.affiliation: Laboratory of Plant Physiology, Wageningen University Wageningen, Netherlands.
authors.forename: Carolien
authors.initials: C
authors.lastname: Ruyter-Spira
keywords: abscisic acid; plant architecture; post-attachment resistance; root parasitic plant; strigolactone