Department of Agro-Environmental Chemistry and Plant Nutrition, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Prague, Czech Republic.
Isotope Laboratory, Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic.
PLoS One. 2020 May 15;15(5):e0233055. doi: 10.1371/journal.pone.0233055. eCollection 2020.
Given the close relationship between cytokinins (CKs), photosynthesis and nitrogen metabolism, this study assessed the effect of arsenic (As) contamination on these metabolic components in the As-hyperaccumulators Pteris cretica L. var. Albo-lineata (Pc-A) and var. Parkerii (Pc-P) as well as the As-non-hyperaccumulator Pteris straminea Mett. ex Baker (Ps). The ferns were cultivated in a pot experiment for 23 weeks in soil spiked with As at the levels 20 and 100 mg·kg-1. For the purpose of this study, the CKs were placed into five functionally different groups according to their structure and physiological roles: bioactive forms (bCKs; CK free bases); inactive or weakly active forms (dCKs; CK N-glucosides); transport forms (tCKs; CK ribosides); storage forms (sCKs; O-glucosides); and primary products of CK biosynthesis (ppbCKs; CK nucleotides). An important finding was higher CKs total content, accumulation of sCKs and reduction of dCKs in As-hyperaccumulators in contrast to non-hyperaccumulator ferns. A significant depletion of C resources was confirmed in ferns, especially Ps, which was determined by measuring the photosynthetic rate and chlorophyll fluorescence. A fluorescence decrease signified a reduction in the C/N ratio, inducing an increase of bioactive CKs forms in Pc-P and Ps. The impact of As on N utilization was significant in As-hyperaccumulators. The glutamic acid/glutamine ratio, an indicator of primary N assimilation, diminished in all ferns with increased As level in the soil. In conclusion, the results indicate a large phenotypic diversity of Pteris species to As and suggest that the CKs composition and the glutamic acid/glutamine ratio can be used as a tool to diagnose As stress in plants.
鉴于细胞分裂素 (CKs)、光合作用和氮代谢之间的密切关系，本研究评估了砷 (As) 污染对 Pteris cretica L. var. Albo-lineata (Pc-A) 和 var. Parkerii (Pc-P) 这两种砷超积累植物以及 Pteris straminea Mett. ex Baker (Ps) 这一非砷超积累植物这些代谢成分的影响。本研究通过盆栽实验，在土壤中添加 20 和 100mg·kg-1 的 As，用 23 周的时间来培育这些蕨类植物。本研究根据其结构和生理作用将 CKs 分为五个不同的功能组：生物活性形式（bCKs；CK 游离碱基）；非活性或弱活性形式（dCKs；CK N-葡萄糖苷）；运输形式（tCKs；CK 核苷）；储存形式（sCKs；O-葡萄糖苷）；CK 生物合成的初级产物（ppbCKs；CK 核苷酸）。一个重要的发现是，与非超积累蕨类植物相比，砷超积累植物的 CKs 总含量较高，sCKs 积累，dCKs 减少。通过测量光合速率和叶绿素荧光，证实了蕨类植物中 C 资源的大量消耗，尤其是 Ps。荧光降低表明 C/N 比降低，导致 Pc-P 和 Ps 中生物活性 CKs 形式增加。As 对超积累植物中氮利用的影响是显著的。土壤中 As 水平升高时，所有蕨类植物的谷氨酸/谷氨酰胺比值（指示初级氮同化）均降低。综上所述，这些结果表明凤尾蕨属植物对 As 具有较大的表型多样性，并表明 CKs 组成和谷氨酸/谷氨酰胺比值可以作为诊断植物 As 胁迫的工具。
