CellBio  Vol.8 No.3 , September 2019
The Effects of Lead on the Meristem of Wheat Seedlings
Abstract: The ultrastructure of apical meristem cells was studied in Triticum aestivum L. cv. “Trizo” seedlings grown on soil without or enriched with selenium and survived 14 days’ stress caused by lead pollution in the soil. The soil treatments: control—the original soil; (Pb1)—50 mg·kg−1; (Pb2)—100 mg·kg−1; (Pb1 + Se1) —0.4 mg·kg−1 Se added to Pb1 treated soil; (Pb1 + Se2)—0.8 mg·kg−1 Se added to Pb1 treated soil; (Pb2 + Se1)—0.4 mg·kg−1 Se added to Pb2 treated soil; (Pb2 + Se2)—0.8 mg·kg−1 Se added to Pb2 treated soil were used. Light and other conditions were optimal for plant growth. A distinctive feature of the cells of the apical meristem of control plants was the absence of nuclear membranes. Proplastids were membrane vesicles 1 - 2 microns in diameter, filled with contents of varying degrees of density, from membrane vesicles containing only plastid DNA up to a fully formed structure of proplastids. In (Pb1)-plants, the amount of cytoplasmic ribosomes and proplastids in the meristematic cells was less than in the control. The structure of the forming proplastids was almost the same as that of the control plants. Signs of degradation of meristematic proplastids, such as a decrease of their diameter, observed in (Pb2)-plants. The introduction of selenium into lead contaminated soil increased the accumulation of Pb in plants, especially in the roots and apical meristem. In (Pb1 + Se1)-, (Pb1 + Se2)-, (Pb2 + Se1)-, and (Pb2 + Se2)-plants, the number of cytoplasmic ribosomes in meristematic cells increased, which indirectly indicates an increase in protein synthesis. Based on our concept about the formation (assembly) of proplastids in the cells of the apical meristem, we believe that toxic agents, such as lead, which inhibit the development of proplastids into chloroplasts in mesophyll cells, act on apical meristem cells at the stage when plastid DNA is replicated in the cytoplasm and is not yet surrounded by a plastid membrane.
Cite this paper: Semenova, G. , Fomina, I. , Bakaeva, E. and Balakhnina, T. (2019) The Effects of Lead on the Meristem of Wheat Seedlings. CellBio, 8, 41-51. doi: 10.4236/cellbio.2019.83003.

[1]   Balakhnina, T.I. and Nadezhkina, E.S. (2017) Effect of Selenium on Growth and Antioxidant Capacity of Triticum aestivum L. during Development of Lead-Induced Oxidative Stress. Russian Journal of Plant Physiology, 64, 215-223.

[2]   Semenova, G.A., Fomina, I.R., Kosobryukhov, A.A., Lyubimov, V.Yu., Nadezhkina, E.S. and Balakhnina, T.I. (2017) Mesophyll Cell Ultrastructure of Wheat Leaves Etiolated by Lead and Selenium. Journal of Plant Physiology, 219, 37-44.

[3]   Fargašová, A., Pastierová, J. and Svetková, K. (2006) Effect of Se-Metal Pair Combinations (Cd, Zn, Cu, Pb) on Photosynthetic Pigments Production and Metal Accumulation in Sinapis alba L. Seedlings. Plant, Soil and Environment, 52, 8-15.

[4]   Lin, L., Zhou, W., Dai, H., Cao, F., Zhang, G. and Wu, F. (2012) Selenium Reduces Cadmium Uptake and Mitigates Cadmium Toxicity in Rice. Journal of Hazardous Materials, 235-236, 343-351.

[5]   Semenova, G.A. (2018) Formation of Proplastids in the Apical Meristem of Wheat. Journal of Plant Cell Development, 1, 23-30.

[6]   Pyke, K.A. (2007) Plastid Biogenesis and Differentiation. In: Bock, R. (Ed.), Cell and Molecular Biology of Plastids, Topics Current Genetics, vol. 19, Springer, Berlin, Heidelberg, 1-28.