The Oryza sativa (rice) carotenoid cleavage dioxygenase OsZAS was described to produce zaxinone, a plant growth-promoting apocarotenoid. A zas mutant line showed reduced arbuscular mycorrhizal (AM) colonization, but the mechanisms underlying this behavior are unknown. Here, we investigated how OsZAS and exogenous zaxinone treatment regulate mycorrhization. Micromolar exogenous supply of zaxinone rescued root growth but not the mycorrhizal defects of the zas mutant, and even reduced mycorrhization in wild-type and zas genotypes. The zas line did not display the increase in the level of strigolactones (SLs) that was observed in wild-type plants at 7 days post-inoculation with AM fungus. Moreover, exogenous treatment with the synthetic SL analog GR24 rescued the zas mutant mycorrhizal phenotype, indicating that the lower AM colonization rate of zas is caused by a deficiency in SLs at the early stages of the interaction, and indicating that during this phase OsZAS activity is required to induce SL production, possibly mediated by the Dwarf14-Like (D14L) signaling pathway. OsZAS is expressed in arbuscule-containing cells, and OsPT11prom::OsZAS transgenic lines, where OsZAS expression is driven by the OsPT11 promoter active in arbusculated cells, exhibit increased mycorrhization compared with the wild type. Overall, our results show that the genetic manipulation of OsZAS activity in planta leads to a different effect on AM symbiosis from that of exogenous zaxinone treatment, and demonstrate that OsZAS influences the extent of AM colonization, acting as a component of a regulatory network that involves SLs.
- Klíčová slova
- Oryza sativa, OsPT11, GR24, apocarotenoids, arbuscular mycorrhizal symbiosis, in situ hybridization, strigolactones, zaxinone, zaxinone synthase,
- MeSH
- dioxygenasy * metabolismus MeSH
- karotenoidy metabolismus MeSH
- kořeny rostlin metabolismus MeSH
- mykorhiza * metabolismus MeSH
- rýže (rod) * metabolismus MeSH
- symbióza fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- dioxygenasy * MeSH
- karotenoidy MeSH
Mineral nutrition is one of the key environmental factors determining plant development and growth. Nitrate is the major form of macronutrient nitrogen that plants take up from the soil. Fluctuating availability or deficiency of this element severely limits plant growth and negatively affects crop production in the agricultural system. To cope with the heterogeneity of nitrate distribution in soil, plants evolved a complex regulatory mechanism that allows rapid adjustment of physiological and developmental processes to the status of this nutrient. The root, as a major exploitation organ that controls the uptake of nitrate to the plant body, acts as a regulatory hub that, according to nitrate availability, coordinates the growth and development of other plant organs. Here, we identified a regulatory framework, where cytokinin response factors (CRFs) play a central role as a molecular readout of the nitrate status in roots to guide shoot adaptive developmental response. We show that nitrate-driven activation of NLP7, a master regulator of nitrate response in plants, fine tunes biosynthesis of cytokinin in roots and its translocation to shoots where it enhances expression of CRFs. CRFs, through direct transcriptional regulation of PIN auxin transporters, promote the flow of auxin and thereby stimulate the development of shoot organs.
- Klíčová slova
- macronutrient, nitrate, plant development,
- MeSH
- cytokininy metabolismus MeSH
- dusičnany * metabolismus MeSH
- kořeny rostlin metabolismus MeSH
- kyseliny indoloctové * metabolismus MeSH
- půda MeSH
- regulace genové exprese u rostlin MeSH
- signální transdukce MeSH
- výhonky rostlin MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cytokininy MeSH
- dusičnany * MeSH
- kyseliny indoloctové * MeSH
- půda MeSH
