植物对硼元素的吸收转运机制

硼是植物生长发育所必需的微量元素，但是在世界范围内，土壤中硼含量过高或者过低都会对植物生长产生影响，是农业生产上的主要问题.近来人们对硼的吸收转运机制的研究取得了突破性进展，鉴定了一些硼的转运通道和转运蛋白，例如：NIP5；1、NIP6；1、BOR1和BOR4，并对它们的转运机制有了一些了解.植物在硼缺少的情况下首先通过转运通道NIP5；1把硼吸收到共质体，然后通过转运蛋白BOR1运入中柱；在高硼毒害时，通过转运蛋白BOR4把过多的硼转出植物体，同时在植物中增加糖醇的含量，过表达BOR1或BOR4都能改变植物对硼含量变化的耐受性.因此,对植物中硼吸收转运机制的研究将有利于人们通过生物学手段提高作物对土壤中硼过高或过低的抗性.

Mechanisms of Boron Transport in Plants

Boron is an essential nutrient for the normal growth of higher plants. Boron deficiency is a worldwide problem in major grain producing areas that results in the rapid inhibition of plant growth. In recent years, the studies of the molecular basis of boron absorption and transport in plants has advanced significantly, several boron transports and channels were identified, for examples, NIP5；1, NIP6；1, BOR1 and BOR4. Under boron restriction, boron is taken into the symplasm mainly through NIP5；1, forms boric acid to be transported toward steles via plasmodesmata, then exported into stellar apoplasm by BOR1. In the boron-rich soils, BOR4 is important for the directional export of boron fromthe roots to prevent the accumulation of boron in the xylem or growing cells. The selected or transgenic cultivars with overexpressed transporters BOR1 or BOR4 or increased sugar alcohol content showed increased boron deficiency or toxicity tolerance. The current study of boron absorption and transport mechanisms in plants has provided clues for the improvement of crop production in boron-deficient or boron-toxic soils by manipulating specific boron transporters or channels