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张福锁. 根分泌物与禾本科植物对缺铁胁迫的适应机理[J]. 植物营养与肥料学报, 1995, 1(1): 17-23. DOI: 10.11674/zwyf.1995.0103
引用本文: 张福锁. 根分泌物与禾本科植物对缺铁胁迫的适应机理[J]. 植物营养与肥料学报, 1995, 1(1): 17-23. DOI: 10.11674/zwyf.1995.0103
Zhang Fusuo. ROOT EXUDATES AND THEIR ROLE IN ADAPTATION TO Fe DEFICIENCY IN GRAMINACEOUS PLANTS[J]. Journal of Plant Nutrition and Fertilizers, 1995, 1(1): 17-23. DOI: 10.11674/zwyf.1995.0103
Citation: Zhang Fusuo. ROOT EXUDATES AND THEIR ROLE IN ADAPTATION TO Fe DEFICIENCY IN GRAMINACEOUS PLANTS[J]. Journal of Plant Nutrition and Fertilizers, 1995, 1(1): 17-23. DOI: 10.11674/zwyf.1995.0103

根分泌物与禾本科植物对缺铁胁迫的适应机理

ROOT EXUDATES AND THEIR ROLE IN ADAPTATION TO Fe DEFICIENCY IN GRAMINACEOUS PLANTS

  • 摘要: 本文系统地总结了自然基金重点项目根分泌物在根际微生态系统中的营养机理的研究进展和部分主要成果。研究表明,养分专一性根分泌物是植物营养遗传特性控制基因的标记物,它受某一养分缺乏的诱导,是在植物体内合成并可通过主动分泌作用进入根际的代谢产物。它的合成和分泌只受该养分胁迫的专一诱导和控制,只要改善这一营养状况就能抑制或阻止其合成和分泌。当植物缺乏这一养分时,植物体可通过自身的调节能力,合成专一性物质并自根分泌到根际,促进该养分的活化并提高植物对其吸收利用效率,从而达到克服或缓解该营养胁迫的目的。用单基因突变材料进行的研究表明,植物铁载体的生物合成和吸收利用是受单基因控制的过程。这一发现不仅使人类有可能运用生物学研究技术来解决营养缺乏问题,而且也为有效地利用自然资源、降低生产成本、减少环境污染提供了可能性。麦根酸类(mugineic.acids)植物铁载体(phytosiderophores)在缺铁禾本科植物体内的生物合成,从植物根内向根际的分泌、在根际环境中对铁的活化及植物对F63+植物铁载体螯合体的吸收四个过程组成了禾本科植物对缺铁胁迫的适应机理。植物铁载体只在早晨日出后2~6h内大量分泌的节律性增加了它们在根际土壤中的相对浓度,减少了它们与土壤颗粒的接触和被吸附;分泌部位集中在微生物尚未侵染的根尖避开了微生物的破坏和分解,同时也增加了它们在土壤微区中的相对浓度。分泌作用和螯合作用不受介质pH值和Ca2+离子浓度影响的特性使该机理在经常出现缺铁现象的石灰性土壤上具有特殊意义。研究结果还表明,缺铁可以诱导激活根细胞原生质膜上可能存在的Fe3+植物铁载体复合体的专一性吸收和运载蛋白,高pH值和CaCO3对这一蛋白的载体功能只有很小的抑制作用,即使在pH值和CaCO3含量都较高的石灰性土壤上,也能有效地发挥作用。这一结论揭示了小麦等禾本科植物适应铁胁迫的实质及其生态学意义。

     

    Abstract: The role of root exudates in the adaptation to Fe deficiency in graminaceous plants was studied in nutrient solution and model experiments under controlled environmental conditions. The results demostrated that the specific root exudates were most important marks of the genetic control of the mineral nutrition in plants. The enhancement or inhibition of biosynthesis and release of specific root exudate was controlled by specific nutrient stress. The efficiency of this mechanism was dependent on both element and plant specificity.The results indicated that the release of phytosiderphores are not a specific reaction to iron deficiency, but also to zinc deficiency. The phytosiderophores were able to mobilze not only iron, but also zinc, copper and manganese from calcareous soil. The uptake of phytosiderophore chelated Fe (Ⅲ) was specific to iron deficiency in comprison to zinc and manganese deficiency. The higher efficiency of Fe (Ⅲ) uptake by phytosiderophore chelate compared with synthetic and microbial chelates indicated a specific transport mechanism of phytosiderophore chelated Fe(Ⅲ) in graminaceous plants.

     

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