Godlewski Mirosław, Adamczyk Bartosz
Laboratory of Plant Morphogenesis, Department of Plant Cytology and Cytochemistry, Institute of Plant Physiology, Cytology and Cytogenetics, University of Łódź, 90-237 Łódź, Poland.
Plant Physiol Biochem. 2007 Sep;45(9):657-64. doi: 10.1016/j.plaphy.2007.06.001. Epub 2007 Jun 21.
The aim of our study was to find out if the culture medium of aseptically cultivated seedlings exhibits proteolytic activity and if this event is universal in angiospermous plants. Seedlings of 15 agricultural and wild-living plant species were cultivated for 14days without any addition of nutrients. Our studies showed that roots of higher plants could secrete proteases and that levels of proteolytic activity in the culture medium of individual species (and cultivars of the same species) could be significantly different. The differences between quantities of the secreted proteases were connected neither with the fresh weight of the growing seedlings nor with the surface of the root system. No proteins were required to induce secretion of proteases. The culture medium of a few studied species (Allium porrum, Zea mays, Helianthus annuus) showed the highest proteolytic activity at pH 7. Studies of the influence of standard protease inhibitors showed that examined proteases belong to the cysteine protease family. The results suggest that the apical parts of roots exuded proteases more intensively than mature parts. Our studies suggest that some plant species could develop a strategy to actively increase the level of free amino acids in the soil solution as a source of N. Our results may contribute to studying plant N nutrition in natural ecosystems and to increasing yield after organic fertilization of agricultural species.
我们研究的目的是弄清楚无菌培养幼苗的培养基是否具有蛋白水解活性，以及这一现象在被子植物中是否普遍存在。15种农作物和野生植物的幼苗在不添加任何养分的情况下培养14天。我们的研究表明，高等植物的根能够分泌蛋白酶，并且各个物种（以及同一物种的不同栽培品种）培养基中的蛋白水解活性水平可能存在显著差异。分泌的蛋白酶数量差异既与生长中的幼苗鲜重无关，也与根系表面积无关。诱导蛋白酶分泌不需要蛋白质。一些研究物种（韭葱、玉米、向日葵）的培养基在pH 7时表现出最高的蛋白水解活性。对标准蛋白酶抑制剂影响的研究表明，所检测的蛋白酶属于半胱氨酸蛋白酶家族。结果表明，根尖比成熟部位更强烈地分泌蛋白酶。我们的研究表明，一些植物物种可能会制定一种策略，积极提高土壤溶液中游离氨基酸的水平作为氮源。我们的结果可能有助于研究自然生态系统中的植物氮营养，并有助于提高农作物有机施肥后的产量。
