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我室在盐害(NaCl)显著缓解缺铁植物铁营养状况的研究中取得进展
发布时间:2017-04-25  来源:土壤与农业可持续发展国家重点实验室  浏览:442

    铁是所有生物生长发育的必须营养元素之一,包括植物和动物,因为其参与生物体内众多氧化还原过程,同时还参与植物体内叶绿素的形成。虽然铁在土壤中的含量相当高,但在碱性土壤中,铁是以氧化铁和氢氧化铁的形式存在的,其有效性很低。据报道,世界上大约有三分之一的土壤属于碱性土壤,因此在农业生产上盐毒害是存在的,且与缺铁一样,是植物生长发育的限制因子,然而,目前关于植物如何同时响应缺铁与盐毒害的研究尚不清楚。

     我室沈仁芳课题组以模式植物拟南芥为材料,在水培的条件下,研究了在盐毒害与缺铁同时存在的情况下拟南芥的生长状况。发现盐毒害(外源添加氯化钠)能显著缓解拟南芥对缺铁胁迫的响应,即叶片的失绿现象有所缓解,同时伴随着根系细胞壁半纤维素含量的降低,以及半纤维素/细胞壁所吸附的铁含量的降低,表明外源添加氯化钠能通过促进细胞壁所吸附的铁的释放达到体内铁的再利用。此外,外源添加氯化钠也能促进铁从根部到地上部分的转运,主要是通过上调FRD3 (FERRIC REDUCTASE DEFECTIVE3), YSL2 (YELLOW STRIPE-LIKE) and NAS1 (NICOTIANAMINE SYNTHASE1)这些铁长距离运输相关基因的表达,从而有效的改善了地上部铁的营养状况。本研究为缺铁土壤上植物的生长提供了一种新的策略。

Zhu XF, Wu Q, Zheng L, Shen RF. NaCl alleviates iron deficiency through facilitating root cell wall iron reutilization and its translocation to the shoot in Arabidopsis thaliana. Plant and Soil, doi:  10.1007/s11104-017-3248-3

Abstract

Aims

The present study was undertaken to investigate the mechanism underlying NaCl-alleviated Fe (iron) deficiency in Arabidopsis thaliana Col-0 (Columbia ecotype).

Methods

Six-week-old Col-0 with rosettes of similar diameters was grown in full-strength nutrient solution lacking Fe (Fe-deficient) or full-strength nutrient solution (Fe-sufficient) with or without 10 mM NaCl for 7 days. Roots were then harvested for analysis of total Fe content, soluble Fe concentration, and abscisic acid (ABA) content as well as for cell wall and RNA extraction, while shoots were harvested for total Fe content and soluble Fe concentration measurements.

Results

The total Fe content and the soluble Fe concentration were higher in roots and shoots of −Fe + NaCl-treated plants than −Fe-treated plants, whereas Fe retention in the cell wall was reduced, suggesting the presence of a cell wall Fe-reutilization mechanism. This conclusion was confirmed by the observation that less hemicelluloses Fe was found in plants under −Fe + NaCl treatment. In addition, associated to the upregulation of genes related to the long-distance transport of Fe, such as FRD3 (FERRIC REDUCTASE DEFECTIVE3), YSL2 (YELLOW STRIPE-LIKE), and NAS1 (NICOTIANAMINE SYNTHASE1) under −Fe + NaCl treatment, more Fe was available in shoots. Furthermore, endogenous ABA is involved in NaCl-alleviated Fe deficiency, as the addition of Flu (fluridone), an inhibitor of ABA biosynthesis, abolished the positive effect of NaCl on Fe deficiency.

Conclusions

Under −Fe condition, NaCl not only is involved in the reutilization of cell wall Fe but also participates in the translocation of Fe from root to shoot in Arabidopsis, partially through its effect on ABA contents.

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