title: A tomato strigolactone-impaired mutant displays aberrant shoot morphology and plant interactions.
abstract: Strigolactones are considered a new group of plant hormones. Their role as modulators of plant growth and signalling molecules for plant interactions first became evident in Arabidopsis, pea, and rice mutants that were flawed in strigolactone production, release, or perception. The first evidence in tomato (Solanum lycopersicon) of strigolactone deficiency is presented here. Sl-ORT1, previously identified as resistant to the parasitic plant Orobanche, had lower levels of arbuscular mycorrhizal fungus (Glomus intraradices) colonization, possibly as a result of its reduced ability to induce mycorrhizal hyphal branching. Biochemical analysis of mutant root extracts suggested that it produces only minute amounts of two of the tomato strigolactones: solanacol and didehydro-orobanchol. Accordingly, the transcription level of a key enzyme (CCD7) putatively involved in strigolactone synthesis in tomato was reduced in Sl-ORT1 compared with the wild type (WT). Sl-ORT1 shoots exhibited increased lateral shoot branching, whereas exogenous application of the synthetic strigolactone GR24 to the mutant restored the WT phenotype by reducing the number of lateral branches. Reduced lateral shoot branching was also evident in grafted plants which included a WT interstock, which was grafted between the mutant rootstock and the scion. In roots of these grafted plants, the CCD7 transcription level was not significantly induced, nor was mycorrhizal sensitivity restored. Hence, WT-interstock grafting, which restores mutant shoot morphology to WT, does not restore mutant root properties to WT. Characterization of the first tomato strigolactone-deficient mutant supports the putative general role of strigolactones as messengers of suppression of lateral shoot branching in a diversity of plant species.
authors.affiliation: Institute of Plant Sciences, Agricultural Research Organization, the Volcani Center, PO Box 6, Bet Dagan 50250, Israel. hkoltai@volcani.agri.gov.il
authors.forename: Hinanit
authors.initials: H
authors.lastname: Koltai
authors.forename: Sivarama P
authors.initials: SP
authors.lastname: LekKala
authors.forename: Chaitali
authors.initials: C
authors.lastname: Bhattacharya
authors.forename: Einav
authors.initials: E
authors.lastname: Mayzlish-Gati
authors.forename: Nathalie
authors.initials: N
authors.lastname: Resnick
authors.forename: Smadar
authors.initials: S
authors.lastname: Wininger
authors.forename: Evgenya
authors.initials: E
authors.lastname: Dor
authors.forename: Kaori
authors.initials: K
authors.lastname: Yoneyama
authors.forename: Koichi
authors.initials: K
authors.lastname: Yoneyama
authors.forename: Joseph
authors.initials: J
authors.lastname: Hershenhorn
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Joel
authors.forename: Yoram
authors.initials: Y
authors.lastname: Kapulnik
mesh_terms: D007783:Lactones / Q000737:chemistry / Q000378:metabolism*; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D007783:Lactones; D010940:Plant Proteins; C483518:strigol