A Database for Triticeae and Avena
EXPERIMENTAL INSITUTUE FOR CEREAL RESEARCH
via Mulino, 3 - 26866 S. Angelo Lodigiano (LO), Italy.
M. Perenzin, M. Corbellini, and G. Boggini.
The long-term history of wheat breeding has been characterized
in Italy and elsewhere by the constant release of leading cultivars
that in turn became progenitors of new cultivars, selected to
perform well under intensive crop management. In the present
economic and political context where farmers are forced to optimize
and reduce inputs, there is a need to release genotypes characterized
by high nitrogen-use efficiency.
Our recent data confirm that modern cultivars do not perform
well when the nitrogen supply is reduced. On the other hand,
the reintroduction of old cultivars is not realistic mainly because
of their low harvest index and very poor bread-making quality.
In order to meet the farmer's needs, a breeding strategy based
on selection under low-input management was used, and five lines
with stable yield and quality have been selected. All lines appeared
different from Donald's wheat ideotype at least in terms of plant
height, but highly efficient for dry matter and nitrogen accumulation
in the grain. Further studies are needed to establish if they
really represent an example of high nitrogen use efficiency.
G. Boggini, M. Cattaneo, S. Empilli, and P. Vaccino.
G. Boggini, M. Cattaneo, P. Vaccino, and C. Concaro.
Waxy wheats, characterized by reduction or absence of amylose
in the starch, may find a use in the production of modified food
starch and their flour may be used to extend the shelf life of
baked products. The primary enzyme responsible for the synthesis
of amylose in amyloplast, granule-bound starch synthase (GBSS),
is present in bread wheat in three isoforms encoded by the structural
genes Wx-A1, Wx-B1, and Wx-D1.
We have analyzed 288 cultivars of bread wheat, 139 cultivars
of durum wheat, and about 200 accessions from other Triticum
species in order to find genetic variability for the waxy trait.
Electrophoretic separation of GBSS allowed the identification
of 63 bread wheats deficient in Wx-B1, one in Wx-A1,
and one in Wx-D1 protein isoforms. The wheat accessions
with Wx mutations were evaluated with a Rapid Visco Analyser
to investigate starch properties. All the analyzed cultivars
showed peak and final viscosities different from normal wheat.
Analyses made in order to evaluate the amylose:amylopectin
ratio and the rheological characteristics of the partial-waxy
genotypes have been completed. The results suggest that the loss
of one of the three Wx-protein isoforms is not sufficient for
a significant reduction of amylose content, and the variation
in the gelatinization profiles is probably due to the dimension
or molecular weight of starch granules.
A crossing program to select double and null waxy-wheat mutants
is in progress; double mutants have been selected by means of
N.E. Pogna, L. Gazza, G. Boggini, M. Corbellini, P. Vaccino,
and E. Ponzoni.
Puroindolines a (pin a) and b (pin b), two lipid-binding proteins
affecting grain texture, were investigated in diploid and hexaploid
wheat species by A-PAGE fractionating and PCR amplification.
A-PAGE provided a clear separation of pin a and pin b, which occurred
as two or four major bands in T. aestivum and T. monococcum, respectively.
Using A-PAGE analyses, four different puroindoline patterns were
identified among 67 diploid wheat accessions, all of them exhibiting
a very soft grain texture as determined by the Single Kernel Characterization
System. Among the 66 bread wheat cultivars analyzed, four A-PAGE
patterns, two alleles coding for pina, and four alleles coding
for pinb were identified. Grain softness proved to be associated
with the presence of alleles pina-D1a, and pinb-D1a, coding for
wild-type pin a and pin b, respectively. On the other hand, medium-to-hard
grain texture was associated with either the absence of pin a
(allele pina-D1b) or the occurrence of a single amino-acid substitution
in wild-type pin b (alleles pinb-D1b, and pinb-D1d). Pin b alleles
have been sequenced and Southern analyses are in progress in order
to investigate the structures of the genes.
A. Brandolini, M. Corbellini, and G. Reffo.
A breeding program based on backcrossing and MAS selection
and aimed at the introgression of powdery mildew resistance gene
Pm13, derived from Ae. longissima, in bread wheat cultivars is
currently at the BC5 stage. To fix the gene, a cycle of selfing
will be made this season. Evaluation of lines for similarity
to the recurrent parents also is under way.
A. Brandolini, P. Vaccino, G. Bruschi, and M. Corbellini.
A consensus map of einkorn wheat, obtained in collaboration
with the Max-Planck Institut of Cologne, is completed and published.
The map was used to localize QTL for quality and agronomic traits.
A major QTL for bread-making quality was detected on chromosome
1S, and the gene responsible for free threshing was positioned
on 2S in a position compatible with Tg genes of polyploid
Progenies of two-, three-, and four-way crosses of lines with
good agronomic and quality traits (earliness, free-threshing,
short straw, gluten quality, and large kernel) are ongoing and
at different stages of evaluation.