plant surface microbiology.pdf

11 Interactions of Microbes with Genetically
Modified Plants
Michael Kaldorf, Chi Zhang, Uwe Nehls, Rüdiger Hampp
and François Buscot
1 Introduction
The introduction of molecular biological methods into plant breeding has
offered the possibility to construct genetically modified plants (GMPs) with
new qualities. Major goals of genetic engineering are the improvement of
product quality as well as the enhancement of resistance or tolerance to
pathogen infections, herbicides and abiotic stress factors.
Attempts to improve the quality of agricultural products include the
manipulation of the softening of fruits like strawberry (Jimenez-Bermudez et
al. 2002) and tomato (Quiroga and Fraschina 1997) in order to allow longer
storage after harvesting, the modification of oil composition of oilseed crops
(Thelen and Ohlrogge 2002), or the elevation of the provitamin A content of
rice (Ye et al. 2000) and tomato (Romer et al. 2000). Even in forestry, increased
wood production and quality are of great commercial interest (Mullin and
Bertrand 1998). For example, the lignin content of transgenic aspen, in which
the lignin biosynthesis pathway was downregulated by antisense inhibition,
was greatly reduced (Hu et al. 1999), indicating that some technical limitations
for the use of these fast growing trees for cellulose fiber production (e.g., in
paper industry) might be reduced by genetic engineering.
In contrast to the examples given above, the basic target of constructing
GMPs with enhanced resistance to biotic or abiotic stress factors is not a modified
product quality, but an enhanced productivity and reduction of the production
costs in agriculture and forestry. The possibility to overcome different
types of abiotic stress in GMPs has been demonstrated in several
experiments [e.g., drought-resistant sugar beet (Pilon-Smits et al. 1999), salttolerant
tomato plants (Zhang and Blumwald 2001), or aluminium-resistant
Brassica napus plants (Basu et al. 2001)], but until now, none of these GMPs is
being used for commercial production.
All GMPs introduced on a large scale into agriculture in the 1990s possess
resistance genes either against herbicides or against plant pathogens. Many
different herbicide-resistant transgenic plants like corn, cotton, lettuce,
Plant Surface Microbiology
A.Varma, L. Abbott, D. Werner, R. Hampp (Eds.)
© Springer-Verlag Berlin Heidelberg 2004