Chronica - Acta Horticulturae

Several scientists announced the release of new
table grape cultivars, obtained from breeding
programs carried out in Chile, China, Israel,
Hungary, Korea, Spain, Turkey, and the United
States. Most of these programs make use of
seedless x seedless crosses and in vitro embryo
rescue. Dr. Zhao of the Hebei Academy of
Agricultural and Forestry Sciences, China and
Dr. Sarikhani of the Kyushu University, Japan
reported on the manipulation of the ploidy to
produce triploid seedless varieties.
BREEDING FOR PEST AND
DISEASE RESISTANCE
Bruce Reisch in his introductory talk to the meeting
reported that grape acreage covers only
8% of the total land exploited by agriculture in
Europe, but viticulture accounts for 40% of the
whole amount of pesticides used by the
European growers. This has been a great concern
of grape breeders for a long time and is
testified to the increasing efforts made to elucidate
the genetic determinants of resistance to
pests and pathogens and the very advanced
breeding projects oriented to the production of
resistant lines.
Concerning the basic genetic studies, these
were carried out by segregation analysis using
cross populations and by functional approaches
based on subtractive cDNA libraries and microarray-based
analysis of induced or repressed
genes following pathogen infection.
The resistance to powdery mildew is at the
latest stage of investigation. Candidate genes
underlying a major QTL, corresponding to the
Run1 gene identified in hybrids derived from
Muscadinia rotundifolia, are now being tested
for the complementation of a susceptible genotype.
These candidate genes, that resemble the
barley gene Mla12 and induce a hypersensitive
response, have been definitively located on LG
12. The isolation of several markers tightly
linked to the Run1 gene allowed the construction
of physical maps spanning the chromosomal
region of interest. BAC sequencing is in
progress, according to what Alain Bouquet
A nice view of vineyards from the Rosazzo
Abbey in the Colli Orientali DOC area of
Friuli.
reported on behalf of an international research
group that includes the INRAs of Montpellier,
Colmar and Evry, the University of Montpellier,
and the CSIRO of Australia.
The same Muscadinia rotundifolia carries resistance
also to downy mildew with two genes,
Rpv1 and Rpv2, identified up to now by Laure
Schmidlin, a brilliant PhD student of the Didier
Merdinoglu’s group in Colmar. Rpv2, which is
located on LG 18, is the one with the strongest
effect as it does not allow fungal sporulation
and generates small necrotic spots. Rpv1 is
located on LG 12 in the same region where
Run1 has been identified. It reduces sporulation
and generates necrotic flecks. A strong QTL for
resistance to downy mildew was located on LG
18, in a chromosomal region rich of NBS-LRR
receptors, also by Rudolf Eibach and Eva
Zyprian of the BAFZ of Geilweilerhof, Germany
and Gabriele Di Gaspero of the University of
Udine, Italy, but in this case the source of
resistance came from North American species
of the genus Vitis.
Sarolta Hoffmann, another brilliant PhD student
working in Pal Kozma’s group in Pécs, Hungary,
reported for the first time a source of resistance
to powdery mildew found in V. vinifera ‘Kismis
vatkana’.
Finally, a genetic locus conferring resistance to
Phylloxera has been identified in the rootstock
Börner by Tatjana Wolf of the Geisenheim
Research Centre, Germany. She isolated also a
number of over-expressed genes that are being
sequenced and annotated using cDNA subtractive
libraries and DNA microarrays.
GRAPE TRANSFORMATION
Grape transformation pursues two objectives:
the most common one is to transfer genes of
interest into commercial grape cultivars; the
second one is to create a collection of single
gene mutants for functional genomic studies.
Grape transformation was initiated many years
ago using Agrobacterium-mediated gene
delivery and several presentations in this conference
reported on the refinement of somatic
embryogenesis and plant regeneration techniques.
Two papers, one from Goetz Reustle of
IPR (Institute of Grapevine Breeding), Germany
and the other one from Lucia Martinelli of
IASMA, Italy dealt with the use of the Cre-lox
recombination system to excise selectable markers
and produce transformed plants free of
these markers, for one of which, the nptII gene
that confers resistance to antibiotics, public opinion
raised concern in the past regarding its use
in GM plants.
Genes tentatively transferred in grape were the
GFLV (Grapevine Fanleaf Virus) CP encoding
gene to create resistance to such a virus, endochitinase
and more often antimicrobial peptide
coding genes to confer resistance to the bacterium
Xylella fastidiosa and several pathogenic
fungi, the rd22 and dehydrin genes to confer
Serge Delrot of the University of Poitiers,
France (left) and Mark Thomas of the CSIRO
Plant Industry, Glen Osmond, Australia
(right), testing a glass of white wine at the
welcome party on Sunday evening.
grape resistance to drought and salinity, and the
DefH9-iaaM gene to promote IAA synthesis in
seedless table grape.
The second objective of grape transformation
aims to create lines over-expressing single genes
or – better – to create collections of mutants,
where individual genes have been silenced by
means of different techniques, such as the RNAi
and the siRNA induced gene silencing or mutagenesis-induced
gene knockout: a frontier topic
on which Goetz Reustle and Mark Thomas
amply reported.
TECHNICAL TOURS
The conference participants had the opportunity
to visit the “Vivai Cooperativi Rauscedo”,
which is the largest grape nursery in the world
with over 60 million grapevine plants sold every
year. The director showed the cold store and
packaging facilities, the winery for microvinification
and kindly offered wine testing and a
fine dinner of traditional cuisine.
The second technical visit, which took place in
the afternoon of the second day, was a trip to
several grapevine districts, such as “Collio” and
“Colli Orientali”, where participants were
offered a glass of the well-reputed white wines
(Tocai friulano, Ribolla, Verduzzo). A short stop
at the Aquileia Roman Basilica allowed participants
to see the largest mosaic ever produced in
the Roman Empire, a subject of which was the
logo selected to represent the 9th Conference:
a virgin hanging two clusters of grape.
The gala dinner was offered the third day at the
Summer mansion of the Venetian doge Manin,
with participants entertained by a concert of
baroque music and the French and Portuguese
colleagues anxiously crowding the TV room for
the soccer world cup semi-final game between
their respective countries.
The conference ended with a visit to the
University of Udine experimental farm, where a
significant repository of wild grape species,
breeding lines, international and local varieties
ISHS • 46