Adamczyk B, Godlewski M, Zimny J, Zimny A
Laboratory of Plant Morphogenesis, Department of Plant Cytology and Cytochemistry, Institute of Plant Physiology, Cytology and Cytogenetic, University of Łódź, Łódź, Poland.
Plant Biol (Stuttg). 2008 Nov;10(6):718-24. doi: 10.1111/j.1438-8677.2008.00079.x.
This paper reports on the role of proteases secreted by roots in nitrogen capture by plants. The study was conducted on aseptically cultivated wheat seedlings (Triticum aestivum cv. Tacher) obtained from embryos isolated from grains. Seedlings were cultivated for 21 days on deionised water, Murashige Skoog medium (MS), MS without inorganic nitrogen (IN), and MS without IN, in which IN was replaced by casein (0.01%, 0.1% or 1%). Comparison of seedlings grown on these media showed that casein entirely compensated for the lack of inorganic nitrogen in the medium. Shoots and roots of seedlings cultivated on MS medium with this protein had higher fresh weight than those cultivated on MS medium without casein. The increase in fresh weight of seedlings was correlated with casein concentration and proteolytic activity in the medium. In conclusion, wheat that uses proteases secreted by the roots can directly utilise proteins in the medium as a source of nitrogen without prior digestion by microbial proteases and without protein mineralisation. These results suggest the important role of organic nitrogen fertilisers in increasing wheat yield.
本文报道了根系分泌的蛋白酶在植物氮素捕获中的作用。该研究以从谷物分离的胚获得的无菌培养小麦幼苗（普通小麦品种塔切尔）为材料。幼苗在去离子水、Murashige Skoog培养基（MS）、无无机氮的MS（IN）以及用酪蛋白（0.01%、0.1%或1%）替代无机氮的无IN的MS上培养21天。在这些培养基上生长的幼苗比较表明，酪蛋白完全补偿了培养基中无机氮的缺乏。在含有这种蛋白质的MS培养基上培养的幼苗的地上部分和根系的鲜重高于在不含酪蛋白的MS培养基上培养的幼苗。幼苗鲜重的增加与培养基中酪蛋白浓度和蛋白水解活性相关。总之，利用根系分泌的蛋白酶的小麦可以直接将培养基中的蛋白质作为氮源利用，无需微生物蛋白酶预先消化，也无需蛋白质矿化。这些结果表明有机氮肥在提高小麦产量方面的重要作用。
