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南農：銅抑制水稻硝酸鹽吸收 | NMT植物氮營養創新科研平臺
NMT作為生命科學底層核心技術，是建立活體創新科研平臺的*技術。2005年~2020年，NMT已扎根中國15年。2020年，中國NMT銷往瑞士蘇黎世大學，正式打開歐洲市場。
研究使用平臺：NMT植物氮營養創新科研平臺
期刊：Ecotoxicology and Environmental Safety
主題：銅抑制水稻**鹽吸收
標題：Excess copper inhibits the growth of rice seedlings by decreasing uptake of nitrate
影響因子：4.527
檢測指標：NO3-流速
檢測樣品：根
NO3-流實驗處理方法：
水稻幼苗在氮環境中培養7天后，在0.2μmolL-1 CuSO4和10μmolL-1 CuSO4的無氮環境中處理15天
NO3-流實驗測試液成份：
0.1mM **銨及氯化鈣，pH5.5
作者：南京農業大學陳晨、霍塏
中文摘要（谷歌機翻）
銅（Cu）的毒性對植物的生長具有有害作用，而不同的氮（N）形式對植物對重金屬的吸收和積累的影響也大不相同。然而，目前尚不清楚過量的銅如何抑制不同氮素形態下水稻幼苗的生長。在這里，我們研究了銅毒性抑制不同形式氮素供應的水稻生長的機理。
在0.2μmolL-1 CuSO4或0.2μmolL-1的養分溶液中，水稻幼苗生長在含有0.81 mmol L-1 N的營養液中，如銨鹽（NH4+），**鹽（NO3-）和NH4++ NO3--或無氮（0 N）。10μmolL-1 CuSO4。在供給有NO3-的植物中，在過量的Cu下對芽生長的抑制作用比NH4 +更為明顯。芽中較高的Cu濃度不會誘導這種抑制作用。單獨施用NO3-可使溶液的pH值增加到6.2，但單獨施用NH4+和NH4++ NO3-可以將溶液的pH值分別降低到4.0和4.2。
溶液pH值的增加降低了單獨添加NO3-的水稻芽中的Cu濃度。銅的毒性降低了單獨提供NO3-的水稻幼苗中的NO3-濃度，但增加了提供NH4+或NH4+ + NO3-的植物中NH4+的濃度。通過對凈NO3-通量和NO3-同化酶活性的分析，高Cu水平降低了根部對NO3-的吸收。在過量的銅下，OsNPF6.5，OsNPF2.2和OsNPF2.4基因的轉錄水平受到抑制，而OsNRT2.1，OsNRT2.2和OsNAR2.1的根部升高。
總之，銅毒性通過調節NO3-轉運蛋白基因的表達水平來抑制NO3-的吸收和向上移位。當氮以NO3-的形式供應時，NO3-和總氮濃度的降低會降低水稻幼苗的莖生長。因此，在銅脅迫下，供應有NO3-的水稻幼苗的莖生物量要低于含有NH4 +的水稻。
Effect of Cu on the net NO3− fluxes at the root hair zone of rice. Plants were grown under hydroponic conditions supplied with N as NO3− for 7 days, and then were incubated in s lution without N in the presence of 0.2 μmol L−1 CuSO4 (CK) and10 μmol L−1 CuSO4 (Cu). Photographs of the measuring point (A, B) and the mean fluxes of NO3− within the measu ing period (C) are shown. Data are means of at least 6 replicates.
英文摘要
Copper (Cu) toxicity has a deleterious effect on plant growth, and different nitrogen (N) forms have significantly different impacts on the uptake and accumulation of heavy metals by plants. However, it remains unclear how excess Cu inhibits the growth of rice seedlings under different N forms. Here, we examined the mechanism of Cu toxicity inhibiting the growth of rice supplied with different N forms.
Rice seedlings were grown in a nutrient solution with 0.81 mmol L−1 N, as ammonium (NH4+), nitrate (NO3−) and NH4++ NO3−, or without N (0 N) in the presence of 0.2 μmol L−1 CuSO4 or 10 μmol L−1 CuSO4. The inhibition of shoot growth under excess Cu was more pronounced in plants that were supplied with NO3− than NH4+; such inhibition was not induced by higher Cu concentration in shoots. Applied with NO3− alone increased solution pH value up to 6.2, but supplied with NH4+ alone and NH4++NO3− decreased solution pH value to 4.0 and 4.2, respectively.
The increment of solution pH reduced Cu concentration in shoots of rice supplied with NO3 − alone. Copper toxicity decreased NO3− concentrations in rice seedlings that were supplied with NO3− alone but increased the NH4+ concentrations in plants that were supplied with NH4+ or NH4+ + NO3−. High Cu levels reduced the uptake of NO3− in roots by the analysis of net NO3− flux and NO3− assimilation enzymes activity. Under excess Cu, the transcript levels of OsNPF6.5, OsNPF2.2 and OsNPF2.4 genes were suppressed, while OsNRT2.1, OsNRT2.2 and OsNAR2.1 were raised in roots.
In conclusion, Cu toxicity inhibits NO3− uptake and upward translocation by modulating the expression level of NO3− transporter genes. The reduction in the concentrations of NO3− and total N decreased shoot growth of rice seedlings when N was supplied as NO3−. Hence, rice seedlings supplied with NO3− had lower shoot biomass than those with NH4+ under Cu stress.