Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Aptdo 644, E-48080 Bilbao, Spain.
J Sci Food Agric. 2010 Sep;90(12):1994-9. doi: 10.1002/jsfa.4043.
Tocopherol (vitamin E) is an antioxidant essential in human nutrition. Several approaches have aimed to enhance tocopherol content in crops by the genetic modification of plants, a practice that generates some social concern. As tocopherol accumulates with leaf age in some wild plants and the antioxidant mechanisms respond with flexibility to stress conditions, it is hypothesised that tocopherol content can be increased in edible plants by the manipulation of harvesting time and growth conditions, in particular irradiance.
Ontogenic changes in tocopherol concentration have been studied in photosynthetic tissues of edible leaves (lettuce, spinach, corn salad and dandelion) and green fruits (cucumber and pepper). In all species, tocopherol content increased with tissue age. Spinach showed the fastest rate of tocopherol accumulation, and growth at higher irradiance had a synergistic effect on the rate of accumulation. The same irradiance dependence of this accumulation was observed in fruits, but a final decrease with senescence occurred in cucumber.
This study demonstrates that the content of tocopherol in vegetables can be notably enhanced (or reduced) by simply selecting the appropriate harvesting time and/or by manipulating the environmental conditions during the growth period.
生育酚（维生素 E）是人类营养中必不可少的抗氧化剂。通过对植物进行基因改造来提高作物中生育酚的含量，这是一种引起社会关注的做法。由于生育酚在一些野生植物中的叶龄增加而积累，并且抗氧化机制可以灵活应对胁迫条件，因此人们假设可以通过操纵收获时间和生长条件（特别是光照）来增加食用植物中的生育酚含量。
研究了可食用叶片（生菜、菠菜、玉米沙拉和蒲公英）和绿色果实（黄瓜和辣椒）的光合组织中的生育酚浓度的个体发育变化。在所有物种中，生育酚含量随组织年龄的增加而增加。菠菜显示出最快的生育酚积累速度，在较高光照下生长对积累速度有协同作用。在果实中观察到了这种积累对光照的依赖性，但在黄瓜中会随着衰老而最终下降。
本研究表明，通过简单选择合适的收获时间和/或在生长期间操纵环境条件，蔬菜中生育酚的含量可以显著提高（或降低）。
