School of Plant Biology and Institute of Agriculture, University of Western Australia, Crawley, Western Australia, 6009, Australia; Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, 38040, Pakistan.
Plant Cell Environ. 2015 Apr;38(4):790-9. doi: 10.1111/pce.12450. Epub 2014 Nov 11.
Study of plants with unusual phosphorus (P) physiology may assist development of more P-efficient crops. Ptilotus polystachyus grows well at high P supply, when shoot P concentrations ([P]) may exceed 40 mg P g(-1) dry matter (DM). We explored the P physiology of P. polystachyus seedlings grown in nutrient solution with 0-5 mM P. In addition, young leaves and roots of soil-grown plants were used for cryo-scanning electron microscopy and X-ray microanalysis. No P-toxicity symptoms were observed, even at 5 mM P in solution. Shoot DM was similar at 0.1 and 1.0 mM P in solution, but was ∼14% lower at 2 and 5 mM P. At 1 mM P, [P] was 36, 18, 14 and 11 mg P g(-1) DM in mature leaves, young leaves, stems and roots, respectively. Leaf potassium, calcium and magnesium concentrations increased with increasing P supply. Leaf epidermal and palisade mesophyll cells had similar [P]. The root epidermis and most cortical cells had senesced, even in young roots. We conclude that preferential accumulation of P in mature leaves, accumulation of balancing cations and uniform distribution of P across leaf cell types allow P. polystachyus to tolerate very high leaf [P].
研究具有异常磷（P）生理学特性的植物可能有助于培育更高效利用 P 的作物。当 Ptilotus polystachyus 植株在高 P 供应下生长时，其地上部 P 浓度（[P]）可能超过 40mg P g(-1)干物质（DM）。我们研究了在 0-5mM P 的营养液中生长的 P. polystachyus 幼苗的 P 生理学特性。此外，我们还利用土壤中生长的幼苗的幼叶和根进行了 cryo-扫描电子显微镜和 X 射线微分析。即使在 5mM P 的溶液中，也未观察到 P 毒性症状。在 0.1 和 1.0mM P 的溶液中，地上部 DM 相似，但在 2 和 5mM P 时，DM 降低了约 14%。在 1mM P 时，成熟叶片、幼叶、茎和根中的 [P]分别为 36、18、14 和 11mg P g(-1) DM。叶片钾、钙和镁浓度随 P 供应的增加而增加。叶片表皮和栅栏薄壁组织细胞的 [P]相似。根表皮和大部分皮层细胞已经衰老，即使是在幼根中也是如此。我们的结论是，P 在成熟叶片中的优先积累、平衡阳离子的积累以及 P 在叶片细胞类型中的均匀分布使 P. polystachyus 能够耐受非常高的叶片 [P]。
