The role of the root in water supply and plant viability is especially important if plants are subjected to stress at the juvenile stage. This article describes the study of morphophysiological and cytological responses, as well as elements of the anatomical structure of primary roots of three wheat species, Triticum monococcum L., Triticum dicoccum Shuebl., and Triticum aestivum L., to osmotic stress. It was shown that the degree of plasticity of root morphology in water deficit affected the growth and development of aboveground organs. It was found that in conditions of osmotic stress, the anatomical root modulations were species-specific. In control conditions the increase in absolute values of root diameter was reduced with the increase in the ploidy of wheat species. Species-specific cytological responses to water deficit of apical meristem cells were also shown. The development of plasmolysis, interpreted as a symptom of reduced viability apical meristem cells, was revealed. A significant increase in enzymatic activity of superoxide dismutase under osmotic stress was found to be one of the mechanisms that could facilitate root elongation in adverse conditions. The tetraploid species T. dicoccum Shuebl. were confirmed as a source of traits of drought tolerant primary root system for crosses with wheat cultivars.
Tetraploid species T. dicoccum Shuebl is a potential source of drought tolerance for cultivated wheat, including common wheat. This paper describes the genotyping of nine stable allolines isolated in the offspring from crossing of T. dicoccum x T. aestivum L. using 21 microsatellite (simple sequence repeats—SSR) markers and two cytoplasmic mitochondrial markers to orf256, rps19-p genes; evaluation of drought tolerance of allolines at different stages of ontogenesis (growth parameters, relative water content, quantum efficiency of Photosystem II, electron transport rate, energy dissipated in Photosystem II); and the study of drought tolerance regulator gene Dreb-1 with allele-specific PCR (AS-MARKER) and partial sequence analysis. Most allolines differ in genomic composition and T. dicoccum introgressions. Four allolines—D-b-05, D-d-05, D-d-05b, and D-41-05—revealed signs of drought tolerance of varying degrees. The more drought tolerant D-41-05 line was also characterized by Dreb-B1 allele introgression from T. dicoccum. A number of non-specific patterns and significant differences in allolines in regulation of physiological parameters in drought conditions is identified. Changes in photosynthetic activity in stress-drought are shown to reflect the level of drought tolerance of the forms studied. The contribution of different combinations of nuclear/cytoplasmic genome and alleles of Dreb-1 gene in allolines to the formation of stress tolerance and photosynthetic activity is discussed.
Chl -chlorophyll; ChlFP -chlorophyll fluorescence parameter; Ek -minimum saturation irradiance; ETRmax -PSII maximum electron transport rate; Fm' -maximum fluorescence yield of the light-adapted leaf; Ft -fluorescence yield just before the saturation pulse; RLC -rapid light curve; Y(II)65,625 -PSII quantum yield of photochemical quenching at PPFD of 65 and 625 µmol m -2 s -1 ; Y(NO)65,625 -nonorganized energy passive dissipation in form of heat and fluorescence at PPFD of 65 and 625 µmol m -2 s -1 ; Y(NPQ)65,625nonphotochemical energy conversion due to downregulation mechanisms at PPFD of 65 and 625 µmol m -2 s -1 ; α -the initial slope of RLC.Acknowledgements: This research was carried out in the framework of the project AP05131734 'Physiological and molecular genetic features of the functioning of the photosynthetic apparatus of alloplasmic lines of wheat, obtained as a result of interspecific crossings, in connection with their drought resistance ' (2018-2020). This grant was funded by the Ministry of Education and Science of the Republic of Kazakhstan. Conflict of interest: The authors declare that they have no conflict of interest.
Highlights• PSII quantum yields at early vegetation stages can predict the fertility of wheat • Rapid light curves appeared to be productivity potential indicators • Allolines of T. dicoccum × T. aestivum are perspective for drought tolerance induction
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