Plant Molecular Biology 51: 619–629, 2003.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.
Expression studies of plant genes differentially expressed in leaf and root
tissues of tomato colonised by the arbuscular mycorrhizal fungus Glomus
Jeanette Taylor and Lucy A. Harrier
Crop and Plant Science Division, Kings Buildings, Scottish Agricultural College, West Mains Road, Edinburgh,
Scotland UK. EH9 3JG
Address for Correspondence: Dr. L.A. Harrier, Crop and Plant Science Division, Scottish Agricultural College,
Kings Buildings West Mains Road, Edinburgh, Scotland, UK, Telephone: 00 44 (0)131 5354154, Fax: 00 44 (0)
131 5354144, E-mail: L.firstname.lastname@example.org.
Key words: AM fungi, Differential mRNA display, gene expression, Glomus mosseae, Lycopersicon esculentum
and semi-quantitative RT-PCR
Arbuscular mycorrhizal (AM) fungi are a multifaceted group of mutualistic symbionts that are common to terres-
trial ecosystems. The interaction between AM fungi and plant roots is of environmental and agronomic importance.
Understanding the molecular changes within the host plant upon AM fungal colonisation is a pre-requisite to a
greater understanding of the mechanisms underlying the interaction. Differential mRNA display was conducted
on leaf tissue of tomato plants colonised and non-colonised by the AM fungus Glomus mosseae and ﬁve putative
differentially regulated cDNAs were identiﬁed. All cDNAs isolated shared high sequence similarity to known
plant genes. Differential screening was initially used to establish whether the cDNAs were differentially expressed.
Semi-quantitative RT-PCR was used to establish gene expression patterns for all ﬁve clones within leaf and root
tissue of mycorrhizal and non-mycorrhizal colonised tomato plants. Differential regulation was observed for all
ﬁve cDNAs. Down-regulation within the leaf tissue of mycorrhizal plants was observed for 4 out of the 5 cDNAs
with an up-regulation observed only for one. Tissue speciﬁc regulation was observed for several cDNAs, with
down-regulation observed in mycorrhizal leaf tissue and up-regulation observed within mycorrhizal root tissue as
compared to non-mycorrhizal tissue.
Soil borne fungi of the unique phylum Glom-
eromycetes (Schussler et al., 2001) are obligate sym-
bionts that form mutualistic symbioses with the ma-
jority of higher plant root systems (Smith and Read,
1997). The beneﬁcial effect of the AM fungal sym-
biosis on plant growth and development occurs as the
result of a complex molecular dialogue between the
two symbiotic partners. The identiﬁcation of plants
genes which are either speciﬁcally and/or differen-
tially expressed within the plant upon AM fungal
colonisation is necessary for a greater understanding
of this highly complex interaction.
AM fungal colonisation is localised within the root
tissue of plants, with colonisation greatly affecting
whole plant physiology. Within leaf tissues of myc-
orrhizal plants, there is alteration of photosynthesis
(e.g. Bildusas et al., 1986; Brown and Bethlenfal-
vay, 1987; Davies et al., 1993), leaf hydration (e.g.
Gemma et al., 1997), leaf osmotic potential (e.g.
Goicoechea et al 1997), stomatal conductance (e.g.
Augé et al., 1992; Davies et al., 1993), reproduction
(e.g. Pendleton, 2000; Poulton et al., 2001, 2002)
and transpiration (e.g. Allen, 1982; Hardie, 1985;