Influence of Seed Origin on Morphological Characteristics and Phytochemicals Levels in Brassica oleracea var. acephala

Brassica oleracea var. acephala production and seed selection in the Mediterranean region is traditionally limited to private, family needs or small enterprises. In recent years it became popular, especially in the US, and known as a superfood due to the presence of specialized metabolites associated with health benefits, mainly from polyphenols, glucosinolates, and carotenoids groups. With the increasing popularity of this plant, there is a growing interest in its commercial production. Therefore, in the present work we aimed to study how seed origin influences the content of specialized metabolites in B. oleracea var. acephala. We grew plants from six different seed producers, in a hydroponic system under controlled conditions, and determined seed germination percentage, morphological characteristics, pigments, polyphenols, glucosinolates, and carotenoids content, as well as antioxidant activity. Seed origin influenced germination percentage, yield, and slightly morphological characteristic, but did not influence pigments, total polyphenols, phenolic acids, glucosinolates, and carotenoids content. However, content of flavonoids, ferulic, sinapinic, and, consequently, antioxidant activity was slightly different

Salinity Stress as an Elicitor for Phytochemicals and Minerals Accumulation in Selected Leafy Vegetables of Brassicaceae

The potential role of NaCl (50–200 mM) as an eustressor for the accumulation of health promoting phytochemicals and maintaining the homeostasis of macro- and micro-elements in three, hydroponically grown Brassica leafy vegetables (Chinese cabbage, white cabbage, and kale) was investigated. Considering K+/Na+ ratio and proline contents as reliable stress markers, we confirmed more prominent stress status in Chinese cabbage followed by white cabbage and kale. Low to moderate salinity treatments (50 and 100 mM NaCl) caused an increase in most of the phenolic compounds in the analyzed Brassica leafy vegetables. Total glucosinolates were elicited by NaCl in a dose dependent manner. Salt treatment caused an increase in total chlorophylls but did not significantly affect carotenoid content. Furthermore, low to moderate treatments did not significantly disturb homeostasis of macro- and micro-elements, particularly in white cabbage and kale where the K level did not decrease significantly and Ca was even increased in white cabbage. We may conclude that salinity may elicit phytochemical accumulation in selecting vegetables grown on saline soils without undesirable disturbance in macro- and micro- elements homeostasis depending on salt concentration and species/varieties. This information may be of great importance in the selection of crops grown on saline soils

Beneficial Microbes and Molecules for Mitigation of Soil Salinity in Brassica Species: A Review

Salt stress results from excessive salt accumulation in the soil can lead to a reduction in plant growth and yield. Due to climate change, in the future climatic pressures, changed precipitation cycles and increased temperature will increase the pressures on agriculture, including increasing severity of salt stress. Brassica species contains oilseed and vegetable crops with great economic importance. Advances in understanding the mechanisms of salt stress in Brassica plants have enabled the development of approaches to better induce plant defense mechanisms at the time of their occurrence through the use of beneficial microorganisms or molecules. Both endophytic and rhizospheric microbes contribute to the mitigation of abiotic stresses in Brassica plants by promoting the growth of their host under stress conditions. In this review we summarized so far reported microorganisms with beneficial effects on Brassica plants and their mode of action. Another approach in mitigating the harmful effect of soil salinity may involve the application of different molecules that are involved in the stress response of Brassica plants. We reviewed and summarized their potential mode of action, methods of application and pointed out further research directions

Effects of short-term xposure to low temperatures on proline, pigments, and phytochemicals level in kale (Brassica oleracea var. acephala)

Kale (Brassica oleracea var acephala) is known as a vegetable with good tolerance of environmental stress and numerous beneficial properties for human health, which are attributed to different phytochemicals. In the present study, investigation of how low temperatures affect proline, pigments and specialized metabolites content was performed using 8-weeks old kale plants subjected to chilling (at 8 °C, for 24 h) followed by short freezing (at −8 °C, for 1 h after previous acclimation at 8 °C, for 23 h). Plants growing at 21 °C served as a control. In both groups of plants (exposed to low temperatures and exposed to short freezing) a significant increase in proline content (14% and 49%, respectively) was recorded. Low temperatures (8 °C) induced an increase of pigments (total chlorophylls 7%) and phytochemicals (phenolic acids 3% ; flavonoids 5% ; carotenoids 15% ; glucosinolates 21%) content, while exposure to freezing showed a different trend dependent upon observed parameter. After freezing, the content of chlorophylls, carotenoids, and total phenolic acids retained similar levels as in control plants and amounted to 14.65 ± 0.36 mg dw g−1, 2.58 ± 0.05 mg dw g−1 and 13.75 ± 0.07 mg dw CEA g−1, respectively. At the freezing temperature, total polyphenol content increased 13% and total flavonoids and glucosinolates content decreased 21% and 54%, respectively. Our results suggest that acclimatization (23 h at 8 °C) of kale plants can be beneficial for the accumulation of pigments and phytochemicals, while freezing temperatures affect differently specialized metabolite synthesis. The study suggests that growing temperature during kale cultivation must be considered as an important parameter for producers that are orientated towards production of crops with an increasing content of health- related compounds

Comparative analysis of phytochemicals and activity of endogenous enzymes associated with their stability, bioavailability and food quality in five Brassicaceae sprouts

Five Brassicaceae sprouts (white cabbage, kale, broccoli, Chinese cabbage, arugula) were comparatively analyzed based on phytochemicals (polyphenols, glucosinolates, carotenoids, chlorophylls, ascorbic acid) content and accompanying enzymes associated with phytochemical stability and bioavailability (peroxidases, myrosinase, and polyphenoloxidase) that consequently impact food quality. Significantly high content of polyphenols and glucosinolates, as well as a high antioxidant activity were found in white cabbage, followed by kale sprouts. In addition, white cabbage contained higher amount of fibers and lower polyphenol-oxidase activity which potentially indicates prevention of browning and consequently better sprout quality. Arugula and broccoli showed higher activity of myrosinase that may result in higher bioavailability of active glucosinolates forms. According to our data, sprouts are cheap, easy- and fast-growing source of phytochemicals but also they are caracterized by different endogenous enzymes activity. Consequently, this parameter should also be taken into consideration in the studies related to the health benefits of the plant-based food