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APAGE of seed gliadin revealed that the strong bands of S. africanum concentrated on aggregated zone and omaga-secalin zone (Shewry and Miller 1983), and the bands in gamma, beta and alpha zone are quite weak (Fig. 4). Most of the bands in amphiploid overlap in the corresponding zones from that in T. durum and S. africanum. But the aggregated secalin zone from S. africanum and weak gliadin bands in gamma and beta zones from both parents were not observed in those of amphiploid.

Resistance investigation of T. durum-S. africanum amphiploid were conducted with references to its parents when inoculated by powdery mildew isolates and stripe rust races (Table 1). S. africanum showed high resistance to these tested isolates in seedling and adult plants, respectively, T. durum showed high susceptible to powdery mildew isolates in seedling, but show intermediate to stripe rust races in adult plants. But the amphiploid with 2n=42 displayed high resistance to both diseases. These results indicated that the disease resistance from S. africanum was totally expressed in the amphiploid background.


Discussion

A stable amphiploid is a permanent resource to combine the genetic variations of donor species. The amphiploid between T. durum cv. Ailanmai and S. africanum contained the valuable genes from AABB genome from T. durum and RaRa genome of S. africanum. It was a new type of hexaploid triticale and can serve as a novel germplasm for triticale improvement. By crossing of the amphiploid with wheat, it can also provide desirable genes to wheat breeding.

To transfer the available genes from alien species, the characterization of alien chromatin in wheat background was vital. Giemsa-C banding techniques made chromosome identification fast, reliable and economical (Gill et al. 1991; Jiang et al. 1994). C-banded mitotic metaphase cell allows distinguishing the chromosomes from T. durum and S. africanum in the amphiploid (Fig. 2). Above all, five pairs of chromosomes with strong telomeric heterchromatins derived from S. africanum (Bennett et al. 1977) were easily observed, and the other two pairs of chromosomes with their characterized C-bands also were longer than the chromosomes of T. durum (Fig. 2). Therefore, in the process of gene transfer, the band pattern of S. africanum can be used to identify the introgression of S. africanum chromatin in wheat background.

The endosperm storage protein have been considered as useful genetic marker and utilized for gene pool evaluations, cultivar identification and chromosome markers for directed genetic manipulation (Konarev et al. 1979). In the amphiploid or F1 hybrids, the electrophoresis patterns were often additive , with bands from both parents. The present study showed that most gliadin and glutenin from T. durum and S. africanum were expressed in the endosperm of the amphiploid and these band patterns also confirmed the genealogy of the amphiploid. The gliadin patterns of S. cereale were used to trace the rye chromosome 1RS in wheat background (Sozinow et al. 1987). Therefore, the similar gliadin band pattern of S. africanum can also used as genetic marker to detect the corresponding chromosome in gene transfers to wheat.

The variation in HMW glutenin subunits, of wheat accounted for most of the variation in bread making qualities (Payne et al. 1987). Determination of HMW glutenin subunits was of importance to evaluate its quality contribution. Recently, we transfer the subunit 23+18 of Glu-B1 from a hexaploid triticale to Sichuan wheat. The result indicated that the advanced lines with this subunits appear relatively higher protein contents and SDS sedimentation volume than recipient wheat-with subunit 7+8 by Glu-B1. It is likely that the subunits 23+18 has a good influence for bread-making quality of wheat. The amphiploid expressed the subunits 2* of Glu-A1 and 23+18 of Glu-B1 from its Ailanmai parents. It is thus to note that the amphiploid can be used as a resources to exploit the desirable glutenin subunits to wheat quality improvement.

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