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

Autores: Calvo-Polanco, M.; Ibort, P.; Molina, S.; Ruiz-Lozano, J. M.; Zamarreño Arregui, Ángel; García-Mina Freire, José María; Aroca, R.
Título de la revista: PLANTA
ISSN: 0032-0935
Volumen: 246
Número: 5
Páginas: 987 - 997
Fecha de publicación: 2017
Lugar: WOS
The effect of ethylene and its precursor ACC on root hydraulic properties, including aquaporin expression and abundance, is modulated by relative air humidity and plant sensitivity to ethylene. 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 (Lp(o)) of non-treated WT plants, and the opposite effect in nr mutants. The treatment with ACC reduced Lp(o) in WT plants at low RH and in nr plants at high RH. The application of AIB increased Lp(o) 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 Lp(o) 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 Lp(o) to environmental changes.