Morpho-Anatomical and Biochemical Characterization of Embryogenic and Degenerative Embryogenic Calli of Phoenix dactylifera L.

Abstract

The study of morpho-anatomical aspects, metabolic changes of proteins, antioxidant substances, as well as phenolic compounds in embryogenic callus (EC) and degenerative embryogenic callus (DEC) was the aim of the present investigation. Ability to form somatic embryos (SEs) was associated with the softness of the EC, which exhibited a white or creamy color and was composed of isodiametric cells containing dense cytoplasm, conspicuous nuclei and minimal vacuoles with observed mitotic activity. Furthermore, protein, reduced glutathione (GSH) and ascorbic acid (ASC) concentrations and the ratio between ASC and dehydroascorborbic acid (DHA) were increased significantly in the EC in comparison to the DEC. In addition, the phenolic extract of the EC was proved to have higher scavenging activity than the extract from the DEC. A loss of embryogenic competence in the DEC was correlated with the presence of more rigid clumps and such calli had a yellowish to brown color and no cell division could be observed in the cells of such aggregates as the cells had large vacuoles and they have very thick walls. Moreover, these morphological and anatomical observations of the DEC were accompanied by accumulations of the oxidized form of ascorbic acid (DHA), H2O2, total soluble phenolic compounds and overaccumulation of naringenin. Alternations in cellular metabolism can affect and regulate the morphogenesis of somatic embryos.

Antioxidants Application Enhances Regeneration and Conversion of Date Palm (Phoenix dactylifera L.) Somatic Embryos

“…Also, endogenous antioxidant levels were discovered to be higher in proliferative cells than in developing cells [ 6 , 9 , 20 ]. Furthermore, Zein El Din et al [ 5 ] observed that the reduced forms of ASC and GSH were identified in higher amounts in EC than in the degenerative embryogenic callus (DEC) of date palm cv. Barhee grown in vitro.…”

“…Protein content within EC cells increased when EC was placed in antioxidants containing media ( Figure 2 A). The importance of protein deposition in EC can be explained by its correlation with higher cell division, and metabolic activities in date palm embryogenic callus [ 5 ] and in nodular cluster cultures of Vriesea reitzii [ 30 ]. Moreover, it has been discovered that proteins were stored in the nucleus of EC at a high level [ 31 ].…”

“…Several studies have been conducted in order to increase the productivity of somatic embryos with high qualitative and quantitative characteristics. Furthermore, these studies were carried out by analyzing the biochemical components of zygotic embryos (ZEs) and simulating their endogenous hormonal, nutritional, and reduced-oxidized environments, as well as providing the appropriate physical conditions throughout somatic embryogenesis [ 3 , 4 , 5 ]. In general, during growth and development, the cellular redox milieu is altered, and it is detected by special sensors that activate particular metabolic pathways, causing short- and long-term reactions [ 6 ].…”

“…Moreover, early embryonic stages, high ASC/DHA and GSH/GSSG ratios stimulate cellular proliferation. While low ASC/DHA and GSH/GSSG ratios promote embryo development and increase embryos number and conversion rate that improve the quality of produced SEs [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ].…”

Influence of maturity stages on postharvest physico-chemical properties of grapefruit (Citrus paradisi var. ‘Shamber Tarnab’) under different storage durations

“…The marketability of fruits and vegetables depends on the quality attributes such as physical appearance, firmness, and shelf life of commodities which are important from the consumer point of view (Abdallah et al, 2021). At the time of purchasing, consumers judge the quality of commodities based on the appearance and firmness of fruits and vegetables (Rezk et al, 2019;Dawi et al, 2021;Zein et al, 2021). Storage performance and quality of fruits depend on maturity stages.…”