An insight into tissue culture-induced variation origin shared between anther culture-derived triticale regenerants

Abstract

Background: The development of the plant in vitro techniques has brought about the variation identified in regenerants known as somaclonal or tissue culture-induced variation (TCIV). S-adenosyl-L-methionine (SAM), glutathione (GSH), low methylated pectins (LMP), and Cu(II) ions may be implicated in green plant regeneration efficiency (GPRE) and TCIV, according to studies in barley (Hordeum vulgare L.) and partially in triticale (× Triticosecale spp. Wittmack ex A. Camus 1927). Using structural equation models (SEM), these metabolites have been connected to the metabolic pathways (Krebs and Yang cycles, glycolysis, transsulfuration), but not for triticale. Using metabolomic and (epi)genetic data, the study sought to develop a triticale regeneration efficiency statistical model. The culture's induction medium was supplemented with various quantities of Cu(II) and Ag(I) ions for regeneration. The period of plant regeneration has also changed. The donor plant, anther-derived regenerants, and metAFLP were utilized to analyze TCIV concerning DNA in symmetric (CG, CHG) and asymmetric (CHH) sequence contexts. Attenuated Total Reflectance-Fourier Transfer Infrared (ATR-FTIR) spectroscopy was used to gather the metabolomic information on LMP, SAM, and GSH. To frame the data, a structural equation model was employed.

Results: According to metAFLP analysis, the average sequence change in the CHH context was 8.65%, and 0.58% was de novo methylation. Absorbances of FTIR spectra in regions specific for LMP, SAM, and GSH were used as variables values introduced to the SEM model. The average number of green regenerants per 100 plated anthers was 2.55.

Conclusions: The amounts of pectin demethylation, SAM, de novo methylation, and GSH are connected in the model to explain GPRE. By altering the concentration of Cu(II) ions in the medium, which influences the amount of pectin, triticale's GPRE can be increased.

Keywords: Anther culture; Copper ions; DNA methylation; DNA sequence; GSH; Green plant regeneration efficiency; Low methylated pectins; SAM; Structural equation modeling; Triticale.

Fig. 1

The schematic illustration of relationships between the biochemical pathways and cycles and the hypothesized SEM model, along with FTIR spectra bands specific for the metabolomic compounds included in the model The hypothesized SEM model with variables Cu(II), CHH_DNMV, CHH_SV, the FTIR absorbances at: 990.950 cm⁻¹ assigned to low methylated pectins (LMP), 1630…1470 cm⁻¹ assigned to S-adenosyl-L-methionine (SAM), and 2550 − 2540 cm⁻¹ assigned to glutathione (GSH) as a function of GPRE (in purple). Red arrows indicate the SEM paths, whereas metabolites in the SEM are indicated by blue fonts and by blue arrows, indicating their position in biochemical paths and cycles and respective FTIR bands. The action of pectins via ascorbic acid (AA) on the tricarboxylic acid cycle (TCA) / Krebs cycle and the involvement of AA in the ascorbate-glutathione cycle, as well as other paths and cycles are given in green. Cu(II) (in red) denotes the concentration of copper ions (M) in the IM. GPRE stands for green plant regeneration efficiency (number of regenerants per 100 plated anthers). CHH_SV and CHH_DNMV are the metAFLP quantitative characteristics of sequence variation and de novo DNA methylation variation affecting CHH sequence contexts (in the dark), respectively λ ₁ -λ ₁₂ path coefficients, δ ₁ -δ ₅ residuals (experimental errors)