CAJ | 학술논문

研究了渗透胁迫和盐胁迫下一年生胡杨(Populus euphratica Oliv.)幼苗的木质部汁液脱落酸(ABA)、离子浓度及叶片气体交换的变化.PEG 6000 (溶液渗透势 -0.24 MPa)、50 mmol/L含钠离子的盐溶液 (NaNO3∶NaHCO3∶NaH2PO4=5∶4∶1, pH 6.8, 渗透势 -0.24 MPa)和50 mmol/L含氯离子的盐溶液 (KCl∶NH4Cl=1∶1, 渗透势 -0.24 MPa) 3种处理都显著降低了苗木的净光合速率(Pn)和蒸腾速率(TRN),但盐处理植株的TRN高于PEG处理的苗木.木质部汁液ABA的浓度在PEG处理后1 h达到峰值,之后开始下降,降到对照水平后又逐渐回升.盐处理苗木的ABA也是在处理开始后就迅速升高,但之后ABA水平明显高于PEG处理的植株.结果显示,渗透胁迫和离子胁迫都能提高胡杨木质部汁液ABA的浓度: 盐处理开始后ABA的迅速升高主要是渗透胁迫的作用,而此后离子胁迫(Na+和Cl-)对ABA水平的提高具有重要作用.钠盐处理对胡杨净光合速率和蒸腾速率的抑制作用高于氯盐处理,其木质部汁液中较高水平的ABA和盐离子(Na+和Cl-)是可能的原因.钠盐处理苗木的盐离子(Na+和Cl-)水平高于氯盐处理,主要是由以下两方面的原因所致: (1)细胞膜上的Ca2+被Na+所取代, 增加了膜的透性; (2)胡杨根细胞液泡对Na+的区隔化能力较弱(与区隔Cl-相比).另外,盐胁迫下胡杨能保持对营养元素K+、Ca2+和Mg2+的吸收,这也是其抗盐性强的重要原因.
연구료삼투협박화염협박하일년생호양(Populus euphratica Oliv.)유묘적목질부즙액탈락산(ABA)、리자농도급협편기체교환적변화.PEG 6000 (용액삼투세 -0.24 MPa)、50 mmol/L함납리자적염용액 (NaNO3∶NaHCO3∶NaH2PO4=5∶4∶1, pH 6.8, 삼투세 -0.24 MPa)화50 mmol/L함록리자적염용액 (KCl∶NH4Cl=1∶1, 삼투세 -0.24 MPa) 3충처리도현저강저료묘목적정광합속솔(Pn)화증등속솔(TRN),단염처리식주적TRN고우PEG처리적묘목.목질부즙액ABA적농도재PEG처리후1 h체도봉치,지후개시하강,강도대조수평후우축점회승.염처리묘목적ABA야시재처리개시후취신속승고,단지후ABA수평명현고우PEG처리적식주.결과현시,삼투협박화리자협박도능제고호양목질부즙액ABA적농도: 염처리개시후ABA적신속승고주요시삼투협박적작용,이차후리자협박(Na+화Cl-)대ABA수평적제고구유중요작용.납염처리대호양정광합속솔화증등속솔적억제작용고우록염처리,기목질부즙액중교고수평적ABA화염리자(Na+화Cl-)시가능적원인.납염처리묘목적염리자(Na+화Cl-)수평고우록염처리,주요시유이하량방면적원인소치: (1)세포막상적Ca2+피Na+소취대, 증가료막적투성; (2)호양근세포액포대Na+적구격화능력교약(여구격Cl-상비).령외,염협박하호양능보지대영양원소K+、Ca2+화Mg2+적흡수,저야시기항염성강적중요원인.
We investigated the osmotic stress and ion-specific effects on xylem abscisic acid (ABA), ion uptake and transport and gas exchange in one-year-old seedlings of Populus euphratica Oliv. Net photosynthetic rates (Pn) and unit transpiration rates (TRN) were both significantly decreased upon an osmotic shock caused by PEG 6000 solution (osmotic potential=-0.24 MPa) or a saline, which was applied by 50 mmol/L Na+-salts (NaNO3∶NaHCO3∶NaH2PO4=5∶4∶1, pH 6.8, osmotic potential=-0.24 MPa) or by 50 mmol/L Cl--salts (KCl∶NH4Cl=1∶1, osmotic potential=-0.24 MPa). However, salt-treated P. euphratica plants maintained typically higher TRN than those exposed to PEG. Xylem ABA concentrations increased rapidly following the PEG treatment, exhibiting peaking values at 1 h, then returning to pre-stress levels, followed by a gradual increase. Similarly, both Na+-treated and Cl--treated trees exhibited a rapid rise of ABA after salt stress was initiated. Notably, salt-treated plants maintained a relatively higher ABA than PEG-treated plants in a longer term. Collectively, results suggest that osmotic stress and ion-specific effects were both responsible for salt-induced ABA in P. euphratica: the initial rapid increase of xylem ABA appears to be a consequence of an osmotic shock, whereas specific salt effects seem to be responsible for ABA accumulation later on. Compared with Cl--treated trees, a higher inhibitory effect on gas exchange (Pn and TRN) was observed in Na+-salt plants, resulting from its long-sustained ABA and higher salt concentrations in the xylem. Displacement of membrane-associated Ca2+ by Na+ and the lesser capacity in Na+ compartmentation in root vacuoles likely contribute to the high influx of Na+ and Cl- in Na+-treated plants. Xylem K+, Ca2+ and Mg2+ concentrations were elevated by external Na+-salts and Cl--salts, suggesting that P. euphratica maintained a higher capacity in nutrient uptake under saline conditions, which makes a contribution to its salinity tolerance.