Changes in Photosynthetic Pigments Content in Non-Transformed and AtCKX Transgenic Centaury (Centaurium erythraea Rafn) Shoots Grown under Salt Stress In Vitro

Abstract

The effects of graded sodium chloride (NaCl) concentrations (0-, 50-, 100-, 150-, and 200-mM) on photosynthetic pigment contents in in vitro grown shoots of important medicinal plant species (Centaurium erythraea Rafn) were investigated. Non-transformed, one AtCKX1 and two AtCKX2 transgenic centaury lines, with altered cytokinin profiles, were used in this study. The chlorophyll (Chl) and carotenoid contents differed in the non-transformed and transgenic lines. In general, salinity significantly reduced the Chl a and Chl b contents in comparison to the NaCl-free medium. The lowest Chl content was observed in AtCKX2 transgenic shoots grown on all the culture media. The total carotenoid content was increased in shoots of non-transformed and both AtCKX2 transgenic lines grown in 50-mM NaCl. On the other hand, in concentrations ˃50-mM NaCl, the total carotenoid content was decreased in all analysed centaury shoots. The Chl a/Chl b ratio in all the shoots increased progressively in the graded NaCl concentrations. Contrarily, the addition of NaCl in the culture medium reduced the Chl/carotenoid ratio in centaury shoots. Taken together, the results of this study partly explained the mode of centaury plant adaptations to salt stress in vitro. Thus, the results on centaury shoots confirmed that the determination of the photosynthetic pigment contents can be a very useful non-destructive screening method in order to discriminate susceptible and resistant plant species/lines to salt stress conditions.

Role of Sodium Nitroprusside on Potential Mitigation of Salt Stress in Centaury (Centaurium erythraea Rafn) Shoots Grown In Vitro

“…This work demonstrated that total Chl content was significantly decreased in control shoots grown on NaCl in comparison to the other control group of shoots grown on ½MS medium ( Figure 3 a). These results are in accordance with the results previously obtained in centaury shoots grown during NaCl-caused salt stress in vitro [ 37 , 39 ]. The lowest SNP concentration applied at pretreatment (50 μM) shown a positive effect on total Chl content in centaury leaves during salt stress.…”

“…The results presented in this work showed that NaCl had negative effect on total carotenoid content in centaury shoots grown in control conditions ( Figure 3 b). Decreased carotenoid content was also recently reported in centaury shoots under salt stress in vitro [ 39 ]. In centaury shoots treated with NaCl, the application of SNP pretreatments resulted in increased total carotenoid content in comparison to control group of shoots grown on medium also supplemented with NaCl.…”

“…Isolation of total chlorophyll ( Chl ) and carotenoids was accomplished from the leaves collected from the bottom part of the centaury rosette after four weeks of cultivation. Total Chl and carotenoid content were extracted using 96% ethanol as proposed by Lichtenthaler [ 43 ] and previously described in detail by Trifunović-Momčilov et al [ 39 ]. The absorbance of the photosynthetic pigments was measured using a UV–visible spectrophotometer (Agilent 8453, Life Sciences, Santa Clara, CA, USA).…”

“…Among the species belonging to the Centaurium genus, centaury is the plant species to which the greatest attention has been paid during recent years. The first and most important reason is the relatively easy manipulation of this plant species, which makes it an excellent model system for studying genetic transformation, secondary metabolites and salt stress physiology [ 37 , 38 , 39 , 40 ]. Moreover, centaury has recently shown to possess great developmental plasticity and the ability to induce somatic embryogenesis in root and leaf cultures [ 41 ].…”

Hydrogen peroxide as attenuator of salt stress effects on the physiology and biomass of yellow passion fruit

“…According to Figure 5A, the increase in the ECw decreased the chlorophyll a content of yellow passion fruit by 17.38% per unit increase in electrical conductivity of water, i.e., in yellow passion fruit plants irrigated with ECw of 2.8 dS m -1 the chlorophyll a concentration was reduced by 41.54% compared to plants under the lowest value of ECw (0.7 dS m -1 ). The degradation of photosynthetic pigments in plants grown under water salinity is probably a consequence of increased toxic ions, increased activity of the chlorophyllase enzyme, and damage to the photosynthetic apparatus (Trifunovic-Momcilov et al, 2021). As noted by Lima et al (2020), the increase in ECw from 0.3 to 3.5 dS m -1 led to reduction in the Chl a concentrations of yellow passion fruit plants.…”