Department of Plant Nutrition, Aula Dei Experimental Station (CSIC), P.O. Box 13034, E-50080 Zaragoza, Spain.
J Plant Physiol. 2010 Mar 1;167(4):255-60. doi: 10.1016/j.jplph.2009.09.007. Epub 2009 Oct 24.
In this study, the effects of Fe resupply on the composition of the xylem sap and apoplastic fluid of Fe-deficient sugar beet plants were investigated. Experiments were carried out in growth chambers with plants grown in hydroponics, and Fe resupply to Fe-deficient plants was carried out by adding 45muM Fe(III)-EDTA to the nutrient solution. In the short term (within 24h), Fe resupply caused marked changes in the xylem sap and apoplastic fluid composition and in leaf physiological parameters when de novo chlorophyll (Chl) synthesis was still beginning. Major changes included: (i) 10- and 5-fold increases in Fe concentrations in apoplastic fluid and xylem sap, respectively; (ii) marked decreases in the concentrations of organic acids in apoplastic fluid, but not in xylem sap and (iii) large decreases in the citrate/Fe ratios, both in apoplastic fluid and in xylem sap. Two to four days after Fe resupply, xylem sap and apoplastic fluid Fe and organic acid concentrations and pH reached values similar to those obtained in Fe-sufficient leaves. Leaf mesophyll ferric chelate-reductase (FC-R) activities and photosynthetic rates increased gradually during recovery from Fe deficiency.
在这项研究中，研究了铁供应对缺铁甜菜植物木质部汁液和质外体液组成的影响。在生长室中用水培植物进行了实验，并通过向营养液中添加 45μM Fe(III)-EDTA 来向缺铁植物供应铁。在短期内（24 小时内），当新合成叶绿素（Chl）仍在开始时，铁供应导致木质部汁液和质外体液组成以及叶片生理参数发生明显变化。主要变化包括：（i）质外体液和木质部汁液中的铁浓度分别增加了 10 倍和 5 倍；（ii）质外体液中有机酸浓度明显降低，但木质部汁液中没有；（iii）质外体液和木质部汁液中的柠檬酸/铁比均大幅降低。铁供应后 2 至 4 天，木质部汁液和质外体液中的铁和有机酸浓度以及 pH 值达到了在铁充足叶片中获得的值。在从缺铁中恢复时，叶片叶肉铁螯合还原酶（FC-R）活性和光合速率逐渐增加。
