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 - 5.05
ISOLATION OF GENES RESPONSIVE TO WATER STRESS
IN POTATO CELL CULTURES
COSTA
A.*, DI GIACOMO M.*, MASSARELLI I.*, LEONE A.**, GRILLO S.*
*) Research Institute for Vegetables and
Ornamental Plant Breeding - CNR-IMOF, Portici, Italy
**) Department of Pharmaceutical Science,
University of Salerno, Italy
water stress, gene isolation,
cDNA-AFLP, potato
Drought is one of major stress limiting
factors for crop productivity. This stress condition affects almost all plant
functions, including growth and development. Plants respond to osmotic stresses
by activating mechanisms of repair and protection of cellular metabolism as a
result of the action of different genes that operate in a complex and
coordinate network. In order to identify key genes involved in response to
drought, we studied the differential expression of potato cells upon
PEG-mediated osmotic stress of different intensity (5-20% PEG) and duration
(15min, 1h, 24h). The systematic comparison, by cDNA-AFLP, of changes in gene
expression during gradual adaptation to low water potential with those induced
by abrupt exposure to water stress, allowed to identify cDNA fragments specific
for each response. As first screening, about 60 cDNAs fragments were identified
as to be differentially expressed. Fourteen cDNA clones were isolated and their
pattern of expression confirmed a clear up-regulation upon stress as determined
by RT-PCR. Many of these AFLP tags match typical stress responsive genes
belonging to different functional classes, i.e. protein synthesis (elongation factor
1a, ribosomal proteins), chaperone activity and protein degradation (hsp20,
RER), ROS scavenging pathway (phenylalanine ammonia-lyase, peroxidase).
Sequence homology search revealed that the remaining six cDNA clones encode
hypothetical or unknown proteins, never described as to be stress-inducible
before. Three cDNAs are highly homologous to potato or tomato EST, one
homologous to a cDNA expressed during arabidopsis seed development. When potato cDNA
sequences were converted into arabidopsis hortologs, conserved domains were identified, such as plant
DNA binding homodomain (clone #96) or transmembrane domains (clones #102 and
103). No hits were found in current databases for fragments #114 and 131.
Further characterization of the most interesting clones is in progress for the
isolation of the corresponding full-length cDNAs and the functional analysis of
the genes in arabidopsis
mutants.