Sulfur nutrition stimulates lead accumulation and alleviates its toxicity in Populus deltoides

作   者：马超峰，陈颖豪，丁申，李子良，石文广，张一，罗志斌
期刊名称：Tree Physiology
影响因子：3.389
卷 期 号：38
页     码：1724-1741
关键词：glutathione, lead, phytochelatin, phytoremediation, poplar, sulfate transporter, sulfur.
论文摘要：
Sulfur (S) can modulate plant responses to toxic heavy metals, but the underlying physiological and transcriptional regulation
mechanisms remain largely unknown. To investigate the effects of S supply on lead (Pb)-induced toxicity in poplars, Populus
deltoides monilifera (Aiton) Eckenw. saplings were exposed to 0 or 50 μM Pb together with one of the three S concentrations (0
(low S), 100 (moderate S) or 1500 (high S) μM Na2SO4). Populus deltoides roots absorbed Pb and it was partially translocated to
the aerial organs, thereby decreasing the CO2 assimilation rate and leaf growth. Lead accumulation in poplars caused the overproduction
of O2
− and H2O2 to induce higher levels of total thiols (T-SH) and glutathione (GSH). Lead uptake by the roots and its
accumulation in the aerial organs were repressed by low S application, but stimulated by high S supply. Lead-induced O2
− and
H2O2 production were exacerbated by S limitation, but alleviated by high S supply. Moreover, the concentrations of S-containing
antioxidants including T-SH and GSH were reduced in S-deficient poplars, but increased in high S-treated plants, which corresponded
well to the changes in the activities of enzymes involved in S assimilation and GSH biosynthesis. The transcript levels of
both genes encoding sulfate transporters, i.e., SULTR1.1 and SULTR2.2, were elevated by low S application or high S supply in
the roots, and the transcriptional upregulation of both genes was more pronounced under Pb exposure. Furthermore, the mRNA
levels of several genes involved in S assimilation and the biosynthesis of GSH and phytochelatins, i.e., ATPS1, ATPS3, GSHS1,
GSHS2 and PCS1, were upregulated in poplar roots with high S supply, particularly under Pb exposure. These results indicate
that a high S supply can stimulate Pb accumulation and reduce its toxicity in poplars by improving S assimilation and stimulating
the biosynthesis of S-containing compounds including T-SH and GSH.