Seedling Biometry of Knockout and Knockout Barley Lines under Ionizing Radiation.

The genes and play a regulatory role in cuticle organization in barley. A knockout (KO) of each gene may alter plant mechanisms of adaptation to adverse environmental conditions. A putative pleiotropic effect of or gene mutations in barley can be assessed in a series of experiments in the presence or absence of a provoking factor. Ionizing radiation is widely used in research as a provoking factor for quantifying adaptive potential of living organisms. Our aim was to evaluate initial stages of growth and development of barley lines with a KO of or under radiation stress. Air-dried barley grains with different KOs and wild-type control (WT) were exposed to γ-radiation at 50, 100, or 200 Gy at a dose rate of 0.74 R/min. Approximately 30 physiological parameters were evaluated, combined into groups: (1) viability, (2) radiosensitivity, and (3) mutability of barley seed progeny. Seed germination, seedling survival, and shoot length were similar among all barley lines. Naked KO lines showed lower weights of seeds, roots, and seedlings and shorter root length as compared to KO lines. The shoot-to-root length ratio of KO lines' seedlings exceeded that of KO and WT lines. In terms of the number of seedlings with leaves, all the KO lines were more sensitive to pre-sowing γ-irradiation. Meanwhile, the radioresistance of KO lines (50% growth reduction dose [RD] = 318-356 Gy) and WT plants (RD = 414 Gy) judging by seedling weight was higher than that of KO lines (RD = 201-300 Gy). Resistance of KO lines to radiation was also demonstrated by means of root length (RD = 202-254 Gy) and the shoot-to-root length ratio. WT seedlings had the fewest morphological anomalies. In KO lines, mainly alterations of root shape were found, whereas in KO lines, changes in the color and shape of leaves were noted. Thus, seedlings of KO lines are characterized mainly by changes in the root system (root length, root number, and root anomalies). For KO lines, other parameters are sensitive (shoot length and alterations of leaf shape and color). These data may indicate a pleiotropic effect of genes and in barley.