Kovács Zoltán, Soós Áron, Kovács Béla, Kaszás László, Elhawat Nevien, Bákonyi Nóra, Razem Mutasem, Fári Miklós G, Prokisch József, Domokos-Szabolcsy Éva, Alshaal Tarek
Agricultural Botany, Plant Physiology and Biotechnology Department, University of Debrecen, Böszörményi Str. 138, 4032 Debrecen, Hungary.
Institute of Food Science, University of Debrecen, Böszörményi Str. 138, 4032 Debrecen, Hungary.
Plants (Basel). 2021 Jun 23;10(7):1277. doi: 10.3390/plants10071277.
A pot experiment, under greenhouse conditions, was carried out aiming at investigating the agronomic biofortification of alfalfa ( L.) with Se and monitoring the Se uptake and accumulation dynamics within four consecutive harvests within the same growing season. Two ionic Se forms, i.e., sodium selenate (Se (VI)) and sodium selenite (Se (IV)), were applied once at a rate of 1, 10, and 50 mg kg (added on Se basis), while 10 and 50 mg L of a red elemental Se (red Se) were used; all Se treatments were added as soil application. Application of Se (VI) at the rate of 50 mg kg was toxic to alfalfa plants. The effect of Se forms on Se accumulation in alfalfa tissues, regardless of the applied Se concentration, follows: Se (VI) > Se (IV) > red Se. The leaf, in general, possessed higher total Se content than the stem in all the treatments. The accumulation of Se in stem and leaf tissues showed a gradual decline between the harvests, especially for plants treated with either Se (VI) or Se (IV); however, the chemically synthesized red Se showed different results. The treatment of 10 mg kg Se (VI) resulted in the highest total Se content in stem (202.5 and 98.0 µg g) and leaf (643.4 and 284.5 µg g) in the 1st and 2nd harvests, respectively. Similar tendency is reported for the Se (IV)-treated plants. Otherwise, the application of red Se resulted in a lower Se uptake; however, less fluctuation in total Se content between the four harvests was noticed compared to the ionic Se forms. The Se forms in stem and leaf of alfalfa extracted by water and subsequently by protease XIV enzyme were measured by strong anion exchange (SAX) HPLC-ICP-MS. The major Se forms in our samples were selenomethionine (SeMet) and Se (VI), while neither selenocysteine (SeCys) nor Se (IV) was detected. In water extract, however, Se (VI) was the major Se form, while SeMet was the predominant form in the enzyme extract. Yet, Se (VI) and SeMet contents declined within the harvests, except in stem of plants treated with 50 mg L red Se. The highest stem or leaf SeMet yield %, in all harvests, corresponded to the treatment of 50 mg L red Se. For instance, 63.6% (in stem) and 38.0% (in leaf) were calculated for SeMet yield % in the 4th harvest of plants treated with 50 mg L red Se. Our results provide information about uptake and accumulation dynamics of different ionic Se forms in case of multiple-harvested alfalfa, which, besides being a good model plant, is an important target plant species in green biorefining.
在温室条件下进行了一项盆栽试验，旨在研究用硒对紫花苜蓿进行农艺生物强化，并监测同一生长季节内连续四次收获期间硒的吸收和积累动态。两种离子态硒形式，即硒酸钠（Se(VI)）和亚硒酸钠（Se(IV)），以1、10和50 mg/kg（以硒计添加）的速率一次性施用，同时使用10和50 mg/L的红色元素硒（红色硒）；所有硒处理均作为土壤施用。以50 mg/kg的速率施用Se(VI)对紫花苜蓿植株有毒。无论施用的硒浓度如何，硒形式对紫花苜蓿组织中硒积累的影响顺序为：Se(VI)>Se(IV)>红色硒。总体而言，在所有处理中，叶片的总硒含量均高于茎。茎和叶组织中硒的积累在收获期间呈逐渐下降趋势，尤其是用Se(VI)或Se(IV)处理的植株；然而，化学合成的红色硒表现出不同的结果。10 mg/kg Se(VI)处理在第一次和第二次收获时分别导致茎中总硒含量最高（202.5和98.0 μg/g）以及叶中总硒含量最高（643.4和284.5 μg/g）。用Se(IV)处理的植株也有类似趋势。否则，红色硒的施用导致较低的硒吸收；然而，与离子态硒形式相比，四次收获期间总硒含量的波动较小。通过强阴离子交换（SAX）HPLC-ICP-MS测定了用水随后用蛋白酶XIV酶提取的紫花苜蓿茎和叶中的硒形式。我们样品中的主要硒形式是硒代蛋氨酸（SeMet）和Se(VI)，未检测到硒代半胱氨酸（SeCys）和Se(IV)。然而，在水提取物中，Se(VI)是主要的硒形式，而SeMet是酶提取物中的主要形式。不过，Se(VI)和SeMet含量在收获期间下降，除了用50 mg/L红色硒处理的植株的茎。在所有收获中，最高的茎或叶SeMet产量百分比对应于50 mg/L红色硒处理。例如，在第四次收获时，用50 mg/L红色硒处理的植株的茎中SeMet产量百分比计算为63.6%，叶中为38.0%。我们的结果提供了关于多次收获的紫花苜蓿中不同离子态硒形式的吸收和积累动态的信息，紫花苜蓿除了是一种良好的模式植物外，还是绿色生物炼制中的重要目标植物物种。
