关键词: 蓝莓, 根系活力, 矿质元素, 铁代谢, 基因表达

Abstract: In order to reveal the mechanism behind the blueberry acidophilus，this research investigated whether the non-adaptation of blueberries（Vaccinium spp.）to the non-acid soil was associated with the metabolic disorders of the iron nutrition. The two-year seedlings of three blueberry cultivars （Biloxi，O’Neal and Brigitta）were subject to pH 5.5，pH 7.0 and pH 7.5 rhizospheric treatments. After 20 days of treatments，they were harvested to analyze their root activity，malondialdehyde contents，mineral elements content and expression of genes related to iron uptake and transportation. The results showed that the pH 7.0 and pH 7.5 treated hizosphere exhibited gradually decreased root activity and deteriorated membrane lipid oxidation. Meanwhile，the Fe concentration in roots of the pH 7.5 treatmentwas only 53.2% of that under the pH 5.5 treatment. The real-time fluorescent quantitative PCR analysis revealed that，in comparison to the pH 5.5 rhizosphere treatment，the expression levels of FRO2（Ferric reduction oxidase 2），Fer2（Ferritin 2）and Nramp3（Natural resistance-associated macrophage protein 3）in rhizospheric under the pH 7.5 conditions were significantly decreased，while no significant difference was observed in the expression of HA（Plasma membrane H+-ATPase）. The above results indicated that the alkaline treatment suppressed the expression of FRO2，which significantly decreased the Fe3+ reductive capacity in roots. Simultaneously，the iron binding storage and Fe transportation were suppressed，as indicated by the decreased expressions of Fer2 and Nramp3，all of which resulted in decreased Fe contents in blueberry roots and an Fe deficiency in leaves. Considering no regular change in contents of other mineral elements，we deduced that the Fe deficiency and the depressed expression of the Fe metablism related genes may be key factors causing the poor growth of blueberries under alkaline rhizosphere conditions.

Key words: blueberry, root activity, mineral element, iron metabolism, gene expression