Qualitative differences between day- and night-time rhizodeposition in maize (Zea mays L.) as investigated by pyrolysis-field ionization mass spectrometry

Pyrolysis-field ionization mass spectrometry of rhizodeposits – a new approach to identify potential effects of genetically modified plants on soil organisms

“…The C and N concentrations in potato rhizodeposits were lower than the values obtained for maize in our previous research, whereas the concentration of S was higher (Melnitchouck et al, 2005). Since we used the same soil for the two experiments, this difference indicates that the composition of the rhizodeposits may be crop specific.…”

“…This was also concluded from investigations of fulvic acids in fen soils (Leinweber et al, 2001), and more recently, of rhizodeposits leached from non-transgenic crops (Kuzyakov et al, 2003;Melnitchouck et al, 2005). Thus, either a higher sensitivity of Py-FIMS, or principal differences between potato and pea, can explain the disagreement to Gransee and Wittenmeyer (2000), who did not find significant differences in carbohydrates, amino acids and carboxylic acids between the exudates of two non-transgenic pea cultivars with common chromatographic techniques.…”

“…Most intense in the lower mass range were signals assigned to peptides (m/z 45, 57, 70, 74, 84 and 97, 146, 147), heterocyclic N containing compounds (m/z 59, 67, 79, 81, 95, 103, 109) and carbohydrates (m/z 84, 96, 110 and 126). In the medium and higher mass range, signals of phenols and lignin monomers (m/z 152, 178, 180, 194, 196, 208, 210) Figure 1, are explained by the potato rhizopedosits cumulated over the six-week growth period, their microbial decomposition products, and leachable products of interaction with the genuine soil organic matter (Kuzyakov et al, 2003;Melnitchouck et al, 2005). The Py-FI mass spectra in Figure 2 also indicate visual differences in the molecular composition of leachates among the four variants with potatoes grown.…”

“…Recently, pyrolysis-field ionization mass spectrometry (Py-FIMS) was shown to be a rapid and highly sensitive method for the analysis of leached maize rhizodeposits (Kuzyakov et al, 2003), which enabled detection of differences in the composition of maize rhizodeposits between day-and nighttime (Melnitchouck et al, 2005). Rhizodeposits of potato plants have not been investigated by modern analytical methods and, accordingly, rhizodeposits of transgenic plants have not been compared to those of non-transgenic ones.…”

Filamentous fungi isolated from the rhizosphere of melon plants (Cucumis melo L. cv. Gold Mine) cultivated in soil with organic amendments

“…According to Melnitchouk et al (2005) and Wellbaum et al (1999), this may be associated with the changes in the composition of root exudates over the phenological cycle of the plant, causing variation in the rhizodeposition, and with the hydrosoluble substances released by decomposition of organic matter, which represent an energy source promptly available for the microorganisms. In addition, Parkinson et al (1963) apud Souza-Motta et al (2003) mentioned that the young roots are initially colonized by a diversity of soil fungi which after some days are substituted by a more restricted mycobiota that remains until the senescence of the roots.…”