PJB-2018-1615
Effects of NaCl on plant growth, root ultrastructure, water content, and ion accumulation in a halophytic seashore beach plum (Prunus maritima)
Li-Min Wang, Xiao-Li Bu, Jin-Lin Chen, Dong-Feng Huang and Tao Luo
Abstract
A pot culture experiment was conducted to evaluate the effect of NaCl on the growth, root ultrastructure, water content, and ion distribution in two - year - old beach plum (Prunus maritima) seedlings. The seedlings were subjected to different levels of NaCl addition (0, 50, and 150 mM) for 120 days under natural conditions. Under high salinity (150 mM NaCl), the ultrastructure of root cells in P. maritima showed the earliest sign of salt injury: including partial fuzzy nuclear membrane and plasma membrane invagination in the root cells of P. maritima. The root cells were unaffected by low salinity (50 mM NaCl). Their root cells exhibited complete karyotheca, obvious nucleolus, numerous organelles, and normal cell wall structure. However, P. maritima maintained higher water content in plant tissues under salinity conditions compared with that of the control. Meanwhile, the salt - treated seedlings also maintained high concentrations of Ca2+, Mg2+, and K+ in leaf tissues. Furthermore, high salinity led to an increase in K+/Na+, Ca2+/Na+ and Mg2+/Na+ selectivity ratios from stems to leaves in P. maritima seedlings. In addition, the growth rate, fresh and dry weights of P. maritima were significantly promoted by low salinity, whereas the growth parameters were unaffected or even decreased at high salinity compared to that of the control. The results indicated that low salinity had a positive effect on the growth of P. maritima by keeping the normal ultrastructure of root cells and increasing the uptake of Ca2+, Mg2+, and K+ ions, especially in leaf tissues. The negative effect of high salinity on plant growth could be ameliorated to some extent by increasing water content in leaves and selective transport of K+, Ca2+ and Mg2+ from stems to leaves in P. maritima seedlings
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