Abstract：
Broccoli serves as a functional food because it can accumulate selenium (Se), well-known bioactive amino-acid-derived secondary metabolites, and polyphenols. The chemical and physical properties of Se are very similar to those of sulfur (S), and competition between sulfate and selenate for uptake and assimilation has been demonstrated. Towards an efficient agronomic fortification of broccoli florets, the working questions were whether we could overcome this competition by exogenously applying the S-containing amino acids cysteine (Cys) or/and methionine (Met), or/and the precursors of Glucosinolate (GSL) types along with Se application. Broccoli plants were cultivated in a greenhouse and at the beginning of floret growth, we exogenously applied sodium selenate in the concentration gradient of 0, 0.2, 1.5, and 3.0 mM to study the impact of increased Se concentration on the organic S (Sorg) content of the floret. The Se concentration of 0.2 mM (Se0.2) was coupled with the application of Cys, Met, their combination, or a mixture of phenylalanine, tryptophane, and Met. The application took place through fertigation or foliar application (FA) by adding isodecyl alcohol ethoxylate (IAE) or a silicon ethoxylate (SiE) surfactant. Fresh biomass, dry mass, and Se accumulation in florets were evaluated, along with their contents of Sorg, chlorophylls (Chl), carotenoids (Car), glucoraphanin (GlRa), glucobrassicin (GlBra), glucoiberin (GlIb), and polyphenols (PPs), for the biofortification efficiency of the three application modes. From the studied selenium concentration gradient, the foliar application of 0.2 mM Se using silicon ethoxylate (SiE) as a surfactant provided the lowest commercially acceptable Se content in florets (239 μg or 0.3 μmol g-1 DM); it reduced Sorg (-45%), GlIb (-31%), and GlBr (-27%); and it increased Car (21%) and GlRa (27%). Coupled with amino acids, 0.2 mM Se provided commercially acceptable Se contents per floret only via foliar application. From the studied combinations, that of Met,Se0.2/FA,IAE provided the lowest Se content per floret (183 μg or 0.2 μmol g-1 DM) and increased Sorg (35%), Car (45%), and total Chl (27%), with no effect on PPs or GSLs. Cys,Met,Se0.2/FA,IAE and amino acid mix,Se0.2/FA,IAE increased Sorg content, too, by 36% and 16%, respectively. Thus, the foliar application with the IAE surfactant was able to increase Sorg, and methionine was the amino acid in common in these treatments, with varying positive effects on carotenoids and chlorophylls. Only the Cys,Met,Se0.2 combination presented positive effects on GSLs, especially GlRa, but it reduced the fresh mass of the floret. The foliar application with SiE as a surfactant failed to positively affect the organic S content. However, in all studied combinations of Se 0.2 mM with amino acids, the Se content per floret was commercially acceptable, the yield was not affected, the content of GSLs was increased (especially that of GlRa and GlIb), and PPs were not affected. The content of GlBr decreased except for the treatment with methionine (Met,Se0.2/FA,SiE) where GlBr remained unaffected. Hence, the combination of Se with the used amino acids and surfactants can provide enhanced biofortification efficiency in broccoli by providing florets as functional foods with enhanced functional properties.
摘要：
西兰花作为一种功能性食品，因为它可以积累硒（Se），众所周知的生物活性氨基酸衍生的次级代谢产物，和多酚。Se的化学和物理性质与硫（S）非常相似，并且已经证明了硫酸盐和硒酸盐之间在吸收和同化方面的竞争。西兰花小花的有效农艺强化，工作问题是我们是否可以通过外源应用含S的氨基酸半胱氨酸（Cys）或/和蛋氨酸（Met）来克服这种竞争，或/和硫代葡萄糖苷（GSL）类型的前体以及硒的应用。西兰花植物在温室中种植，在小花生长开始时，我们以0、0.2、1.5和3.0mM的浓度梯度外源施用硒酸钠，以研究硒浓度增加对小花有机S（Sorg）含量的影响。0.2mM（Se0.2）的Se浓度与Cys的应用相结合，Met,他们的组合，或苯丙氨酸的混合物，色氨酸,和Met。通过添加异癸醇乙氧基化物（IAE）或硅乙氧基化物（SiE）表面活性剂，通过灌溉施肥或叶面施用（FA）进行施用。新鲜生物质,干质量,并评估了小花中硒的积累，以及他们的索格内容，叶绿素（Chl），类胡萝卜素（汽车），葡萄糖苷(GlRa),葡糖大素（GlBra），葡萄糖苷（GlIb），和多酚（PPs），三种应用模式的生物强化效率。从研究的硒浓度梯度来看，使用硅乙氧基化物（SiE）作为表面活性剂的0.2mMSe的叶面施用提供了小花中商业上可接受的最低Se含量（239μg或0.3μmolg-1DM）；它降低了Sorg（-45％），GlIb（-31%），和GlBr（-27%）；它增加了汽车（21%）和GlRa（27%）。再加上氨基酸，0.2mMSe仅通过叶面施用提供商业上可接受的每个小花的Se含量。从研究的组合中，Met的，Se0.2/FA,IAE提供了每个小花的最低Se含量（183μg或0.2μmolg-1DM）和增加的Sorg（35％），汽车（45%），和总Chl(27%)，对PP或GSL没有影响。Cys,Met,Se0.2/FA,IAE和氨基酸混合，Se0.2/FA,IAE增加了Sorg含量，也是,36%和16%，分别。因此，IAE表面活性剂的叶面施用能够增加Sorg，蛋氨酸是这些治疗中常见的氨基酸，对类胡萝卜素和叶绿素有不同的积极作用。只有Cys,Met,Se0.2组合对GSL有积极影响，尤其是GlRa,但它减少了小花的新鲜质量。以SiE作为表面活性剂的叶面施用未能对有机S含量产生积极影响。然而,在所有研究的硒0.2mM与氨基酸的组合中，每个小花的硒含量是商业上可以接受的，产量没有受到影响，GSL的含量增加(尤其是GlRa和GlIb的含量)，PPs未受影响。除了用蛋氨酸处理外，GlBr的含量降低(Met，Se0.2/FA,SiE），其中GlBr未受影响。因此，Se与使用的氨基酸和表面活性剂的组合可以通过提供小花作为具有增强的功能特性的功能食品而在西兰花中提供增强的生物强化效率。
