Polyamines in conventional and organic vegetables exposed to exogenous ethylene

Organic plant products are of more improved chemical composition than conventional ones

Considering the negative effects of conventional agricultural production, organic food production is a sustainable approach to production, which preserves the environment and protects human health. Organic products are products of high quality, without residues of pesticides and other harmful chemicals. Through the review of literature data, the authors of this paper presented a comparative study on the chemical compositions of organically vs. conventionally grown plants and their products. Dry matter, nitrates, sugars, vitamins, macro-and microelements, as well as, secondary metabolites have been singled out. The analysis of collected data revealed that organic products contained more dry matter, significantly fewer nitrates, fewer proteins and a higher proportion of amino acids, more sugars, vitamin C, numerous macro-and microelements (particularly Fe, Mg and P), more polyphenols and they had higher total antioxidant capacity than conventional products. Although many authors have been dealing for many years with the comparison of the nutritional composition of organic and conventional food products, a clear consensus whether organic products have an improved chemical composition compared to conventional products has not been reached yet, i.e. the conclusions are ambivalent. Therefore, further long-term studies are necessary to clarify the existing doubts.

Organic plant products are of more improved chemical composition than conventional ones

Considering the negative effects of conventional agricultural production, organic food production is a sustainable approach to production, which preserves the environment and protects human health. Organic products are products of high quality, without residues of pesticides and other harmful chemicals. Through the review of literature data, the authors of this paper presented a comparative study on the chemical compositions of organically vs. conventionally grown plants and their products. Dry matter, nitrates, sugars, vitamins, macro-and microelements, as well as, secondary metabolites have been singled out. The analysis of collected data revealed that organic products contained more dry matter, significantly fewer nitrates, fewer proteins and a higher proportion of amino acids, more sugars, vitamin C, numerous macro-and microelements (particularly Fe, Mg and P), more polyphenols and they had higher total antioxidant capacity than conventional products. Although many authors have been dealing for many years with the comparison of the nutritional composition of organic and conventional food products, a clear consensus whether organic products have an improved chemical composition compared to conventional products has not been reached yet, i.e. the conclusions are ambivalent. Therefore, further long-term studies are necessary to clarify the existing doubts.

The Variation Tendency of Polyamines Forms and Components of Polyamine Metabolism in Zoysiagrass (Zoysia japonica Steud.) to Salt Stress with Exogenous Spermidine Application

To understand dynamic changes in polyamines (PAs) forms and components of polyamine metabolism in zoysiagrass (Zoysia japonica Steud.) response to salt stress with exogenous spermidine (Spd) application, two Chinese zoysia cultivars, z081 and z057, were exposed to sodium chloride stress for 2, 4, 6, and 8 days. The z057 cultivar possesses higher salinity tolerance than the z081 cultivar. Salt stress decreased the zoysiagrass fresh weight (FW) and increased free Spd and spermine (Spm) levels and soluble and insoluble putrescine (Put), Spd and Spm levels in both cultivars. Moreover, salt stress enhanced the activities of arginine decarboxylase (ADC), ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), and diamine oxidase (DAO). Exogenous Spd increased PA metabolism and ADC, SAMDC, and DAO activities and decreased free Put levels under salt stress conditions in both cultivars. In addition, structural equation modeling (SEM) showed that ODC, SAMDC, and DAO contributed to PA metabolism, and endogenous Spd levels also contributed to endogenous Spm levels. Free PAs may be the primary factor influencing the variation of other PA forms. SEM also indicated that ADC and polyamine oxidase (PAO) play a limited role in enhancing zoysia salt tolerance via PA metabolism under salt stress.

Low-temperature derivatization followed by vortex-assisted liquid-liquid microextraction for the analysis of polyamines in Nicotiana Tabacum

Polyamines are ubiquitous polycationic molecules that play a key role in many biological processes such as nucleic acid metabolism, protein synthesis, cell growth, and nicotine synthesis precursors. This work describes a rapid, sensitive, convenient, green, and cost-effective method for the determination of polyamines in Nicotiana tabacum by ultra high performance liquid chromatography with photodiode array detection. The analytes were derivatized with 3,5-dinitrobenzoyl chloride at low temperature (about 4°C) and then extracted with vortex-assisted liquid-liquid microextraction. The experimental designs based on quarter-fractional factorial design and Doehlert design were used to screen and optimize the important factors in microextraction process. Under the optimal conditions, the method was linear over 0.05-8.00 μg/mL with an r(2) ≥ 0.992 and exhibited good repeatability and reproducibility less than 6.0 and 6.9%, respectively. The limit of detection ranged between 0.013 and 0.029 μg/g. The newly developed method was successfully employed to analyze different leaf samples of Nicotiana tabacum, among which the polyamines contents were found to be very different. Moreover, tyramine, 1,3-diaminopropane, homospermidine, and canavalmine were tentatively identified with the electrospray ionization quadrupole time-of-flight mass spectrometry. To our knowledge, this is the first report of identification of canavalmine in Nicotiana Tabacum.