Sabharwal N, Icoz I, Saxena D, Stotzky G
Laboratory of Microbial Ecology, Department of Biology, New York University, New York, NY 10003, USA.
Plant Physiol Biochem. 2007 Jun-Jul;45(6-7):464-9. doi: 10.1016/j.plaphy.2007.03.009. Epub 2007 Mar 14.
We determined the release in root exudates of human serum albumin (HSA), beta-glucuronidase (GUS), glycoprotein B (gB) from human cytomegalovirus, and green fluorescent protein (GFP) from genetically modified transgenic tobacco expressing the genes for these proteins in hydroponic culture and non-sterile soil. GUS, gB, and GFP were expressed in the plant but were not released in root exudates, whereas HSA was both expressed in the plant and released in root exudates, as shown by a 66.5-kDa band on SDS-PAGE and Western blot and confirmed by ELISA. Root exudates from GUS and gB plants showed no bands that could be attributed to these proteins on SDS-PAGE, and root exudates from GFP plants showed no fluorescence. The concentration of HSA in root exudates was estimated to be 0.021 ng ml(-1), whereas that in the plant biomass was estimated to be 0.087 ng ml(-1). The concentration of HSA in soil was estimated to be 0.049 ng g(-1). No significant differences in the number of microorganisms and the activity of selected enzymes were observed between rhizosphere soil of non-modified and HSA tobacco.
我们测定了水培和非无菌土壤中人类血清白蛋白（HSA）、β-葡萄糖醛酸酶（GUS）、人巨细胞病毒糖蛋白B（gB）以及表达这些蛋白基因的转基因烟草中的绿色荧光蛋白（GFP）在根系分泌物中的释放情况。GUS、gB和GFP在植物中表达，但未在根系分泌物中释放，而HSA在植物中表达且在根系分泌物中释放，SDS-PAGE和Western印迹显示为一条66.5-kDa条带，ELISA进一步证实。GUS和gB植物的根系分泌物在SDS-PAGE上未显示可归因于这些蛋白的条带，GFP植物的根系分泌物未显示荧光。根系分泌物中HSA的浓度估计为0.021 ng ml⁻¹，而植物生物量中的浓度估计为0.087 ng ml⁻¹。土壤中HSA的浓度估计为0.049 ng g⁻¹。未改良烟草和HSA烟草根际土壤之间的微生物数量和所选酶的活性未观察到显著差异。
