Brown PH, Bellaloui N, Hu H, Dandekar A
Department of Pomology, University of California, Davis, California 95616, USA.
Plant Physiol. 1999 Jan;119(1):17-20. doi: 10.1104/pp.119.1.17.
The mobility of elements within plants contributes to a plant species' tolerance of nutrient deficiencies in the soil. The genetic manipulation of within-plant nutrient movement may therefore provide a means to enhance plant growth under conditions of variable soil nutrient availability. In these experiments tobacco (Nicotiana tabacum) was engineered to synthesize sorbitol, and the resultant effect on phloem mobility of boron (B) was determined. In contrast to wild-type tobacco, transgenic tobacco plants containing sorbitol exhibit a marked increase in within-plant B mobility and a resultant increase in plant growth and yield when grown with limited or interrupted soil B supply. Growth of transgenic tobacco could be maintained by reutilization of B present in mature tissues or from B supplied as a foliar application to mature leaves. In contrast, B present in mature leaves of control tobacco lines could not be used to provide the B requirements for new plant growth. 10B-labeling experiments verified that B is phloem mobile in transgenic tobacco but is immobile in control lines. These results demonstrate that the transgenic enhancement of within-plant nutrient mobility is a viable approach to improve plant tolerance of nutrient stress.
植物体内元素的移动性有助于植物物种对土壤养分缺乏的耐受性。因此，对植物体内养分移动进行基因操作可能提供一种手段，以增强在土壤养分供应可变条件下的植物生长。在这些实验中，对烟草（Nicotiana tabacum）进行基因改造以合成山梨醇，并测定其对硼（B）韧皮部移动性的影响。与野生型烟草相比，含有山梨醇的转基因烟草植株在土壤硼供应有限或中断时，其体内硼的移动性显著增加，从而导致植物生长和产量增加。转基因烟草的生长可以通过重新利用成熟组织中存在的硼或通过向成熟叶片叶面喷施硼来维持。相比之下，对照烟草品系成熟叶片中的硼不能用于满足新植株生长对硼的需求。硼-10标记实验证实，硼在转基因烟草中可通过韧皮部移动，但在对照品系中则不能移动。这些结果表明，通过转基因增强植物体内养分移动性是提高植物对养分胁迫耐受性的一种可行方法。
