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 electrophoretic analysis.
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 wheats.
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.