Ammonium Toxicity Alleviation by Silicon is Dependent on Cytokinins in Tomato cv. Micro-Tom

• Autor(a) principal: Barreto, Rafael Ferreira [UNESP]
• Data de Publicação: 2021
• Outros Autores: de Mello Prado, Renato [UNESP], Lúcio, José Clebson Barbosa [UNESP], López-Díaz, Isabel, Carrera, Esther, Carvalho, Rogério Falleiros [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1007/s00344-021-10314-5; http://hdl.handle.net/11449/207269
• topic: 6- benzyladenine; Ammonium nutrition; Beneficial element; CKX2; Cytokinins deficiency; Solanum lycopersicum

The objectives were to verify the effects of the lack of cytokinins (CKs), comparing tomato cv. Micro-Tom (MT, wild type) to MT CKX2 (transgenic with less CKs) fed with nitrate (NO3−) and ammonium (NH4+), in the presence and absence of silicon (Si); verify if the attenuation of NH4+ toxicity by Si depends on the increase of CKs in MT; and verify if 6-benzyladenine (6-BA) attenuates NH4+ toxicity in MT. Three experiments were performed with treatments via nutrient solution. First, MT and MT CKX2 were grown with NO3− or NH4+ (5.9 mmol L− 1), in the absence and presence of Si (1.28 mmol L− 1). Second, MT was grown with NO3− or NH4+ (5.9 mmol L− 1), in the absence and presence of Si (1.28 mmol L− 1). Third, MT was grown with NO3− or NH4+ (5.9 mmol L− 1) and 6-BA (from 1e−10 to 1e−6 mol L−1) associated with NH4+. The MT and MT CKX2 had a decrease of 18% and 48% in the shoot dry weight, respectively, when fed with NH4+, compared to NO3−. Si attenuated NH4+ toxicity in MT, but not in MT CKX2. This attenuation in MT was accompanied by a decrease in trans-zeatin (tZ) content in the roots and increase in the shoots. 6-BA did not improve the shoot growth of MT fed with NH4+. In conclusion, the alleviation of NH4+ toxicity by Si was dependent on the increase in tZ content in shoots. In CK-deficient plants, Si did not alleviate NH4+ toxicity, and 6-BA did not alleviate NH4+ toxicity in MT shoots.