Book of Abstracts - Geyseco

FESPB 2010 - XVII Congress of the Federation of European Societies of Plant Biology
length, and root length density at 1% and root diameter in 5%. 2)
More tolerant genotypes had more root length, root length density
and less root diameter. 3) the rooting density of sesame in
surface layers is higher 4)sesame rooting depth differs with water
condition 5) non branching genotypes has a better root distribution
in the soil profile in comparison to branching types.
P01-078: BIOCHEMICAL MECHANISMS RELATED TO
ENHANCED CHILLING TOLERANCE IN CHERIMOYA
FRUIT BY POSTHARVEST HIGH-CARBON DIOXIDE
TREATMENT
Goñi, O.* - Sanchez-Ballesta, M.T. - Merodio, C. - Escribano, M.I.
Instituto del Frio (CSIC)
*Corresponding author, e-mail: oscargr@if.csic.es
The tolerance of plants species to chilling can be achieved by
accumulation of substances as osmoprotectants or cryoprotective
proteins. In cherimoya fruit (Annona cherimola Mill.), a
treatment with high concentrations of CO2 enhances its chilling
tolerance during storage at 6ºC. LT-SEM studies in the mesocarp
of treated fruits showed a consolidated structure and maintenance
of membrane integrity.
Consistent with these observations, an accumulation of betaine
was noted in the fruit throughout the storage period. Moreover,
the gaseous treatment induced the synthesis of a low molecular
mass basic chitinase, BChi14, and acidic 1,3-β-glucanase,
AGlu19, which were associated with a raise in the cryoprotective
activity in vitro of protein extracts. Functional study of purified
PR proteins revealed that BChi14 and AGlu19 are very effective
in protecting the cold-labile enzyme LDH from freeze-induced
inactivation. On a molar basis, both enzymes are about 3-times
more effective than the cryoprotective protein BSA.
These results indicate that BChi14, AGlu19 and betaine may be
concerned in the cherimoya active cold defence mechanism induced
by postharvest CO 2
treatment. This protection against chilling
injury could be explained in the context of cross-resistance
between storage at chilling temperatures and a gaseous treatment.
P01-079: PHYTOCHELATINS GOVERN ZINC/COPPER
HOMEOSTASIS AND CADMIUM DETOXIFICATION IN
THE PARASITIC INTERACTION BETWEEN CUSCUTA
CAMPESTRIS AND DAUCUS CAROTA
Sanita’ di Toppi, L.* - Vurro, E. - Ruotolo, R. - Ottonello, S. - Elviri,
L. - Maffini, M. - Falasca, G. - Zanella, L. - Altamura, M.M.
Universitá Degli Studi di Parma
*Corresponding author, e-mail: luigi.sanitaditoppi@unipr.it
Cuscuta sp., a member of the Convolvulaceae family, known
with the common name of “dodder”, is an obligate parasite capable
of invading stems and leaves of a wide range of host plants.
Dodder stem usually coils counterclockwise around the host and,
within a few days, develops haustorial structures at each point
of contact. As soon as dodder haustoria reach the host vascular
bundles, they start tapping water, photosynthates and minerals
from the host. Metal ions such as zinc (Zn) and copper (Cu) are
essential for normal dodder growth and metabolism, although an
exceedingly high (over-homeostatic) supply of these micronutrients
can result in growth inhibition and cellular toxicity. Even
more so, non-essential metals such as cadmium (Cd), if transferred
from the host to the parasite, need to be neutralized by timely
detoxification mechanisms.
The first goal of this work was thus to demonstrate that Cuscuta
campestris can indeed parasitize a model plant such as carrot
(Daucus carota) and establish effective haustorial connections,
capable of transferring Cd and essential metal ions such as Zn
and Cu from the host vascular bundles to the parasite. Having
proven the above point, we subsequently addressed the hypothesis
that the presence of glutathione (GSH) as well as GSH
derivatives such as phytochelatins (PCs) might be particularly
important in dodder for Zn and Cu homeostasis and Cd detoxification.
In fact, throughout its life-cycle, dodder is exposed to
simultaneous fluxes of essential and non-essential metal ions
coming from the host. Last but not least, we wished to verify
whether PCs could be synthesized by C. campestris on its own,
rather than being massively imported from the host.
Results on the above issues will be presented and discussed.
P01-080: ISOLATION AND QUANTITATIVE ANALYSIS
OF HEMOGLOBIN 1 INTO SPINACH TISSUES IN RES-
PONSE TO ANAEROBIOSIS
Antonacci, S.* - Ferrarese, M. - Faoro, F. - Ferrante, A.
DiProVe - Università degli Studi di Milano
*Corresponding author, e-mail: simona.antonacci@unimi.it
Class I Hemoglobins (Hb1s) have an extremely high affinity
for oxygen and are induced in plants during hypoxic and anoxic
stresses or by the oversupply of nitrogen (N) compounds. It
has been proposed that in case of hypoxia Hb1 acts as a nitric
oxide scavenger within a NO 3
-/NO 2
-/NO cycle in which most
intracellular nitrate is utilized. In this case Hb1 activity would
have a dual effect of detoxifying excessive NO production and
tuning NO in its action as a stress signal. Inorder to study Hb1
expression and activity in response to different external stimuli
a full-length coding sequence showing high similarity to known
anaerobiosis-induced non-symbiotic Class1 Hemoglobins was
isolated from anoxic spinach roots. The full length sequence encoded
for a putative protein of 167 aa. Blast analysis showed
conserved protein domains that confirmed the similarity with
Hb1-like protein class. Microarray experiments on 3 h anoxic
roots and qPCR analysis of SoHb1 expression after a prolonged
anaerobic stress showed a strong upregulation in roots and in
leaves collected in the dark from waterlogged spinach plants. In
vivo NO levels were analyzed on anaerobic root samples through
DAF staining and confocal microscopy. The experiments showed
an augmented fluorescence into stressed samples. To further investigate
on Hb1-NO interactions an RNAi construct was designed
with an anti-LyHb1 and tomato plants were transformed.
Transformed lines will be assayed for nitrate metabolism and NO
content under anaerobiosis.
P01-081: PHOTOSYSTEM II EFFICIENCY EXPLAIN A
SIGNIFICANT PART BUT NOT ALL THE REDUCTION
OF RADIATION USE EFFICIENCY OF MAIZE CULTI-
VATED UNDER CHILLING CONDITIONS.
Postaire, O. - Louarn, G. - Fournier, C. - Andrieu - Giauffret C.
INRA
The higher light interception efficiency of the maize is reached
at flowering, which usually occurs at the end of July when solar
radiation is already decreasing. Moreover, water availability after
flowering is often limiting grain filling. Because earlier sowing
would allow a better fit between plants crop cycle and overall
resource availability, breeders are seeking for strategies enabling
plants to grow more efficiently under cool temperature. Biomass
production depends on the amount of photosynthetically active
radiation (PAR) intercepted by the crop and on radiative use efficiency
(RUE). Suboptimal temperatures have negative impact on
PAR interception and on RUE. The aim of this work was to evaluate
the targets for improving maize tolerance to chilling stress
under the field conditions. Field experiments were carried out
from 2005 to 2009 with a flint inbred line from temperate climate.
Each year, two sowing dates were used to generate contrasted
temperatures regimes during seedling establishment. The relative
contribution of the intercepted PAR and the RUE on the biomass
reduction at silking in the early sowings were similar for four
years. Low temperatures reduced the surface of laminas, even
for leaves that were growing after the cold period. Lamina size
reduction is strongly depended on the climatic scenario. RUE
was higly correlated with mean air temperature (r² = 0.91). The
RUE variation during the sowing-silking period can be very high