Proceedings of the XLVI Italian
Society of Agricultural Genetics - SIGA Annual Congress
Giardini
Naxos, Italy - 18/21 September, 2002
ISBN 88-900622-3-1
Poster
Abstract - 5.03
OZONE INDUCED GENE RESPONSES IN TOLERANT AND
SENSITIVE PLANTS
RIZZO
M.*, SALVINI M.*,
**, TADDEI S.*, BERNARDI R.*, NALI C.***, LORENZINI G.***, DURANTE M.*
*)
Dipartimento di Biologia delle Piante Agrarie, Sezione di Genetica, Via
Matteotti 1/B, 56124 Pisa
mrizzo@agr.unipi.it , rbernard@agr.unipi.it , mdurante@agr.unipi.it
**)
Scuola Normale Superiore di Pisa, Piazza dei Cavalieri 7, 56126 Pisa
***)
Dipartimento di Coltivazione e Difesa delle Specie Legnose "G.
Scaramuzzi", Via del Borghetto 80, 56124 Pisa
cnali@agr.unipi.it , glorenz@agr.unipi.it
ozone stress, Phaseolus vulgaris,
Populus, suppression subtractive hybridisation
Among
the major gaseous pollutants, tropospheric ozone surely possesses the higher
phyto-toxic potential: ozone has been demonstrated to alter basic metabolic processes
of plants, and the alterations can affect crop productivity and contribute to
forest decline.
Environmental
concentrations of ozone increased from 1% to 2% per year during the past 20
years in Europe and United States, and in the next decades the critical
threshold concentration of 40 nl l-1 will be reached more often in
rural regions than in urban areas.
The response of
plant to ozone exposure includes a number of physiological and biochemical
changes that are the direct result of selective increase or decreases in gene
expression. Although the physiological and morphological responses of plant to
ozone have been well characterised, little is known about the molecular basis
for these responses.
To elucidate the
molecular mechanisms of ozone responses in arboreous and herbaceous species, we
have chosen hybrid poplars (Populus deltoides x maximowiczii
Eridano clone, O3-sensitive, e P. x euramericana I-214
clone, O3-tolerant) and bean (Phaseolus vulgaris var. Groffi, O 3-tolerant, e Phaseolus
vulgaris var. Pinto, O3-sensitive).
With the aim to
characterise the gene expression induced by ozone exposure and the molecular
basis of ozone tolerance we have applied an improved techniques for finding
differentially regulated genes, such as Suppressive Subtractive Hybridisation
(SSH): this methods is based on the construction of subtracted cDNA libraries
that allow the identification and isolation of differentially expressed
transcript.
At
present we have isolated some interesting clones. The sequences, coming from
automated sequencing of the clones, were analysed using the FASTA, BLAST,
ProDom, BLOCK software for their
identification. For example, in the cDNA library obtained from Phaseolus vulgaris var.
Pinto, O3-sensitive, proteins
were recognised that are required in the defence response for different type of
biotic or abiotic stress (components of 26S proteasome; proteins that catalyse
the covalent attachment of ubiquitin to other proteins; glutathione
S-transferases that participate in the detoxification of reactive electrophilic
compounds by catalysing their conjugation to glutathione). This may suggest
that the mechanisms involving ozone-induced proteins are quite different in
sensitive or tolerant varieties and that the roles of the above mentioned
proteins are not sufficient in conferring tolerance.