Ethylene sensitivity and relative air humidity regulate root hydraulic properties in tomato plants

• Published in: Planta 2017-11, Vol.246 (5), p.987-997
• Main Authors: Calvo-Polanco, Monica, Ibort, Pablo, Molina, Sonia, Ruiz-Lozano, Juan Manuel, Zamarreño, Angel María, García-Mina, Jose María, Aroca, Ricardo
• Format: Article
• Language: English
• Subjects: Abundance; Agriculture; Amino Acids, Cyclic - pharmacology; Aminoisobutyric Acids - pharmacology; Aquaporins; Aquaporins - genetics; Aquaporins - metabolism; Biological Transport; Biomedical and Life Sciences; Biosynthesis; Carboxylic acids; Ecology; Environmental changes; Ethylene; Ethylenes - metabolism; Forestry; Gene Expression Regulation, Plant - drug effects; Genotypes; Humidity; Hydraulic properties; Hydraulics; Kinases; Life Sciences; Lycopersicon esculentum - drug effects; Lycopersicon esculentum - genetics; Lycopersicon esculentum - physiology; ORIGINAL ARTICLE; Phosphorylation; Plant Growth Regulators - metabolism; Plant Leaves - drug effects; Plant Leaves - genetics; Plant Leaves - physiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - genetics; Plant Roots - physiology; Plant Sciences; Plant Stomata - drug effects; Plant Stomata - genetics; Plant Stomata - physiology; Plant Transpiration - physiology; Plants (botany); Properties (attributes); Relative humidity; Sensitivity; Stomata; Tomatoes; Water - metabolism; Water balance; Water uptake
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-017-2746-0

Relative air humidity (RH) is a main factor contributing to water balance in plants. Ethylene (ET) is known to be involved in the regulation of root water uptake and stomatal opening although its role on plant water balance under different RH is not very well understood. We studied, at the physiological, hormonal and molecular levels (aquaporins expression, abundance and phosphorylation state), the plant responses to exogenous 1-aminocyclopropane-1-carboxylic acid (ACC; precursor of ET) and 2-aminoisobutyric acid (AIB; inhibitor of ET biosynthesis), after 24 h of application to the roots of tomato wild type (WT) plants and its ET-insensitive never ripe (nr) mutant, at two RH levels: regular (50%) and close to saturation RH. Highest RH induced an increase of root hydraulic conductivity (Lpₒ) of non-treated WT plants, and the opposite effect in nr mutants. The treatment with ACC reduced Lpₒ in WT plants at low RH and in nr plants at high RH. The application of AIB increased Lpₒ only in nr plants at high RH. In untreated plants, the RH treatment changed the abundance and phosphorylation of aquaporins that affected differently both genotypes according to their ET sensitivity. We show that RH is critical in regulating root hydraulic properties, and that Lpₒ is affected by the plant sensitivity to ET, and possibly to ACC, by regulating aquaporins expression and their phosphorylation status. These results incorporate the relationship between RH and ET in the response of Lpₒ to environmental changes.