Departamento de Ciencias Vegetales, Facultad de Agronomía e Ingeniería Forestal, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, Santiago 7820436, Chile.
Centro UC Desierto de Atacama, Pontificia Universidad Católica de Chile, Avenida Vicuña Mackenna 4860, Macul, Santiago 7820436, Chile.
Int J Mol Sci. 2018 Dec 7;19(12):3921. doi: 10.3390/ijms19123921.
Grafting has become a common practice among tomato growers to obtain vigorous plants. These plants present a substantial increase in nitrogen (N) uptake from the root zone. However, the mechanisms involved in this higher uptake capacity have not been investigated. To elucidate whether the increase in N uptake in grafted tomato plants under high N demand conditions is related to the functioning of low- (high capacity) or high-affinity (low capacity) root plasma membrane transporters, a series of experiments were conducted. Plants grafted onto a vigorous rootstock, as well as ungrafted and homograft plants, were exposed to two radiation levels (400 and 800 µmol m s). We assessed root plasma membrane nitrate transporters ( and ) expression, Michaelis‒Menten kinetics parameters ( and ), root and leaf nitrate reductase activity, and root respiration rates. The majority of nitrate uptake is mediated by and in grafted and ungrafted plants. Under high N demand conditions, vigorous rootstocks show similar levels of expression for and , whereas ungrafted plants present a higher expression of . No differences in the uptake capacity (evaluated as ), root respiration rates, or root nitrate assimilation capacity were found among treatments.
嫁接已成为番茄种植者获得健壮植株的常用方法。这些植株在根区从氮 (N) 中的吸收能力显著提高。然而，涉及这种更高吸收能力的机制尚未得到研究。为了阐明在高氮需求条件下嫁接番茄植株中氮吸收的增加是否与低亲和力（高容量）或高亲和力（低容量）根质膜转运体的功能有关，进行了一系列实验。将植株嫁接到生长旺盛的砧木上，以及未嫁接和同系嫁接的植株，暴露在两种辐射水平（400 和 800 µmol m s）下。我们评估了根质膜硝酸盐转运体（和）的表达、米氏动力学参数（和）、根和叶硝酸还原酶活性以及根呼吸速率。大多数硝酸盐吸收是由 和 在嫁接和未嫁接的植株中介导的。在高氮需求条件下，生长旺盛的砧木表现出相似水平的 和 表达，而未嫁接的植株则表现出更高的 表达。在处理之间，未发现吸收能力（评估为 ）、根呼吸速率或根硝酸盐同化能力有差异。
