Quality of partial waxy and complete waxy tetraploid lines from the durum wheat cultivar Svevo.

The introduction of the "waxy" character in wheat plants is a subject of interest in cereal science and technology. The nutritional and technological properties of waxy cereals, related to the reduced amylose content of waxy starch and to other accompanying features, are in fact very peculiar. At present, the selection of waxy lines from wheat and the assessment of their characteristics and functional properties in relation to specific endproducts are the object of extensive studies worldwide. Our study aimed at characterizing waxy durum wheat lines derived from the Italian cultivar Svevo, widely used in the manufacture of traditional Italian wheat products. This cv., commonly used for pasta making thanks to its good gluten qualities, was crossed with the Japanese bread wheat cultivar Kanto 107 lacking the Wx-A1 and Wx-B1 proteins. Electrophoretic selection of backcrossed generations permitted the production of the two partial waxy lines (wx-A1 and wx- B1 null lines) along with the complete waxy (wx-A1/wx-B1 null line) in durum wheat. Grains of the conventional cv. and of the complete waxy line coming from two harvests (years 2007 and 2008), together with grains of the two partial waxy lines coming from harvest 2008 (not available in 2007) were analysed for thousand kernel weight, ash, insoluble and soluble fibre, total protein, dry gluten, gluten index, SDS sedimentation index, ?-amylase activity, falling number and resistant starch. As regards kernel characteristics of harvest 2008: thousand kernel weight was higher for the wx-A1null line and for the conventional cv., lower for the wx-B1 null line and for the complete waxy line; ash content was lower in the conventional cv., higher in the complete waxy line and intermediate in the two partial waxy lines; protein content was increasing in the order: wx-B1 null, conventional, wx-A1 null, complete waxy. As regards protein quality indicators: relative SDS sedimentation index was not found to be different in the samples, whereas gluten index was halved in the complete waxy line with respect to the conventional cv. and to both the partial waxy lines. As regards parameters related to starch: ?-amylase activity was higher in the complete waxy and in the wx-B1 null lines, lower in the conventional cv.; resistant starch was very low in all samples and therefore it was impossible to detect any difference. Similar results were found for the conventional cv. And the complete waxy line in the 2007 year.