title: Osmotic stress represses strigolactone biosynthesis in Lotus japonicus roots: exploring the interaction between strigolactones and ABA under abiotic stress.
abstract: Strigolactone changes and cross talk with ABA unveil a picture of root-specific hormonal dynamics under stress. Strigolactones (SLs) are carotenoid-derived hormones influencing diverse aspects of development and communication with (micro)organisms, and proposed as mediators of environmental stimuli in resource allocation processes; to contribute to adaptive adjustments, therefore, their pathway must be responsive to environmental cues. To investigate the relationship between SLs and abiotic stress in Lotus japonicus, we compared wild-type and SL-depleted plants, and studied SL metabolism in roots stressed osmotically and/or phosphate starved. SL-depleted plants showed increased stomatal conductance, both under normal and stress conditions, and impaired resistance to drought associated with slower stomatal closure in response to abscisic acid (ABA). This confirms that SLs contribute to drought resistance in species other than Arabidopsis. However, we also observed that osmotic stress rapidly and strongly decreased SL concentration in tissues and exudates of wild-type Lotus roots, by acting on the transcription of biosynthetic and transporter-encoding genes and independently of phosphate abundance. Pre-treatment with exogenous SLs inhibited the osmotic stress-induced ABA increase in wild-type roots and down-regulated the transcription of the ABA biosynthetic gene LjNCED2. We propose that a transcriptionally regulated, early SL decrease under osmotic stress is needed (but not sufficient) to allow the physiological increase of ABA in roots. This work shows that SL metabolism and effects on ABA are seemingly opposite in roots and shoots under stress.
authors.affiliation: Department of Agricultural, Forest and Food Sciences (DISAFA), University of Turin, Largo P. Braccini 2, 10095, Grugliasco, TO, Italy, junweiliu4037@gmail.com.
authors.forename: Junwei
authors.initials: J
authors.lastname: Liu
authors.forename: Hanzi
authors.initials: H
authors.lastname: He
authors.forename: Marco
authors.initials: M
authors.lastname: Vitali
authors.forename: Ivan
authors.initials: I
authors.lastname: Visentin
authors.forename: Tatsiana
authors.initials: T
authors.lastname: Charnikhova
authors.forename: Imran
authors.initials: I
authors.lastname: Haider
authors.forename: Andrea
authors.initials: A
authors.lastname: Schubert
authors.forename: Carolien
authors.initials: C
authors.lastname: Ruyter-Spira
authors.forename: Harro J
authors.initials: HJ
authors.lastname: Bouwmeester
authors.forename: Claudio
authors.initials: C
authors.lastname: Lovisolo
authors.forename: Francesca
authors.initials: F
authors.lastname: Cardinale
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics; D055864:Droughts; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D007783:Lactones / Q000378:metabolism* / Q000494:pharmacology; D000070116:Lotus / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D009997:Osmotic Pressure; D010710:Phosphates / Q000494:pharmacology; D053147:Plant Exudates / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000502:physiology; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013312:Stress, Physiological / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics
chemical_list: C528323:5-deoxystrigol; D007783:Lactones; D010710:Phosphates; D053147:Plant Exudates; D012333:RNA, Messenger; D000040:Abscisic Acid