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中科院南土所丨紅柳和棉花在干旱脅迫下對硝吸收的差異
NMT是基因功能的活體檢測技術(shù)，已被31位諾貝爾獎得主所在單位，及北大、清華、中科院使用。
期刊：Tree Physiology
主題：紅柳和棉花在干旱脅迫下對硝吸收的差異
標(biāo)題：Characterization and comparison of nitrate fluxes in Tamarix ramosissima and cotton roots under simulated drought conditions
影響因子：3.389
檢測指標(biāo)：NO3-流速
檢測樣品：紅柳、棉花根部（距離根尖5mm，20mm）
NO3-流速流實(shí)驗處理方法：
15% PEG瞬時處理
NO3-流速流實(shí)驗測試液成份：
0.1 mM KNO3, 0.1 mM MgCl2, 0.1 mM NaCl, 0.1 mM CaCl2 and 0.3 mM 2-(N-morpholino) ethanesulfonic acid hydrate (MES), pH 6.2
作者：中科院南京土壤所施衛(wèi)明、李光杰、張琳
英文摘要
Tamarix ramosissima Ledeb., a major host plant for the parasitic angiosperm Cistanche tubulosa, and known for its unique drought tolerance, has significant ecological and economic benefits. However, the mechanisms of nitrogen acquisition by the T. ramosissima root system under drought have remained uncharacterized.
Here, uptake of nitrate (NO3−) in various regions of the root system was measured in T. ramosissima using Non-invasive Micro-test Technology at the cellular level, and using a 15NO3–-enrichment technique at the whole-root level. These results were compared with responses in the model system cotton (Gossypium hirsutum L.). Tamarix ramosissima had lower net NO3– influx and a significantly lower Km (the apparent Michalis–Menten constant; 8.5 μM) for NO3– uptake than cotton under normal conditions.
Upon simulated drought conditions, using polyethylene glycol (PEG), NO3– flux in cotton switched from net influx to net efflux, with a substantive peak in the white zone (WZ) of the root. There were no significant NO3– influx signals observed in the WZ of T. ramosissima under control conditions, whereas PEG treatment significantly enhanced NO3– influx in the WZ of T. ramosissima. The effect of PEG application on NO3– fluxes was highly localized, and the increase in net NO3– influx in response to PEG stimulation was also found in C. tubulosa-inoculated T. ramosissima. Consistently, root nitrogen (N) content and root biomass were higher in T. ramosissima than in cotton under PEG treatment.
Our study provides insights into NO3– uptake and the influence of C. tubulosa inoculation in T. ramosissima roots during acclimation to PEG-induced drought stress and provides guidelines for silvicultural practice and for breeding of T. ramosissima under coupled conditions of soil drought and N deficiency.
中文摘要（谷歌機(jī)翻）
Tamarix ramosissima Ledeb。是寄生被子植物肉stan蓉的主要寄主植物，以其*的耐旱性而聞名，具有顯著的生態(tài)和經(jīng)濟(jì)效益。然而，在干旱條件下，T。ramosissima根系對氮素的吸收機(jī)制尚未闡明。
在這里，使用非侵入性微測試技術(shù)在細(xì)胞水平上使用毛細(xì)線蟲，并在全根水平上使用15NO3-富集技術(shù)測量了毛滴蟲在根系各個區(qū)域中**鹽（NO3-）的吸收。將這些結(jié)果與模型系統(tǒng)棉（Gossypium hirsutum L.）中的響應(yīng)進(jìn)行比較。在正常條件下，柳的凈NO3-流入量較低，而NO3-吸收量的Km（表觀Michalis-Menten常數(shù)； 8.5μM）則顯著低于棉花。
在模擬干旱條件下，使用聚乙二醇（PEG），棉花中的NO3-通量從凈流入量轉(zhuǎn)換為凈流出量，在根部的白色區(qū)域（WZ）出現(xiàn)一個實(shí)質(zhì)性的峰值。在控制條件下，沒有觀察到明顯的NO3-流入信號，而PEG處理顯著增強(qiáng)了T. ramosissima的W3區(qū)NO3-流入。 PEG施用對NO3-通量的影響高度局限，并且在接種C.tubulosa的T. ramosissima中還發(fā)現(xiàn)了響應(yīng)PEG刺激的NO3-凈流入量的增加。一致地，在PEG處理下，T.ramosissima的根氮（N）含量和根生物量均高于棉花。
我們的研究為適應(yīng)PEG誘導(dǎo)的干旱脅迫提供了NO3的吸收以及在T. ramosissima根中接種C.tubulosa的影響，并為土壤干旱和N耦合條件下的營林實(shí)踐和T. ramosissima育種提供了指導(dǎo)。不足。
結(jié)果表明：使用PEG進(jìn)行瞬時處理后，棉花根系的NO3-由吸收轉(zhuǎn)為外排，值可達(dá)400 pmol·m-2·s-1，由此降低根系的N含量；而紅柳根系經(jīng)PEG瞬時處理后吸收明顯增加，可達(dá)300 pmol·m-2·s-1，提高了根系的N含量。