**5. Kafirins as the markers of endosperm genetic structure**

In addition to variation of a number of β-kafirin fractions in different sorghum entries described above, we have revealed polymorphism of the α-kafirins. The line Volzhskoe-4w (V-4w) that is used as a tester line to distinguish the hybrid seedlings from the maternal ones, possessed specific kafirin spectrum, which was rarely observed in other sorghum lines and cultivars. The α1 fraction was composed from three polypeptides: α1-1, α1-2, and α1-3; α2 fraction was composed from two polypeptides: α2-1 and α2-2 (Fig. 7, lanes 1-3). We hypothesized that this polymorphism could be used in studies of genetic structure of endosperm in apomixis research in sorghum.

Gel Electrophoresis as a Tool to Study Polymorphism and

marker (kDa). Gels were stained with AgNO3.

methods of classical genetics or genetic engineering.

storage proteins and starch in sorghum endosperm.

2004).

**6. Conclusion** 

Nutritive Value of the Seed Storage Proteins in the Grain Sorghum 475

of a seedling. Another part was used in SDS-PAGE to study its kafirin spectrum. In the case of autonomous endosperm development, no V-4w proteins should be found in the kafirin spectra of the kernels yielded maternal seedlings, while in the case of pseudogamous endosperm development, in the electrophretic spectra of these kernels, the SDS-PAGE must reveal V-4w proteins. It was found that kafirin spectra of kernels, which yielded maternal seedlings (Fig. 7, lanes 11,12) did not differ from the spectrum of AS-1a line (Fig. 7, lanes 4-6), while in the spectra of the kernels, which yielded hybrid seedlings the α1-3 protein was clearly distinguished (Fig. 7, lanes 7-10). These data support the results of our cyto-embryological observations of autonomous endosperm development in the AS-1a line (Elkonin et al., 2012) and are in accordance with the literature data on other sorghum lines with apomictic potentials (Rao et al., 1978; Wu et al., 1994; Ping et al.,

Fig. 7. Kafirin spectra of Volzhskoe-4w (lanes 1-3), AS-1а (4-6) and of the kernels, which were set on emasculated panicles of AS-1a pollinated with the Volzhskoe-4w pollen and yielded the F1 hybrid seedlings (7-10) and maternal plants (11-12); М – molecular weight

Summarizing, the results of our investigation demonstrate that gel electrophoresis of the seed storage proteins is a powerful instrument in researches on sorghum genetics and breeding that have both fundamental and applied orientation. It allowed to isolate of sorghum lines with individual kafirin fractions more sensitive to protease action, and, therefore, with increased protein digestibility – one of the main trait characterizing the nutritive value of sorghum grain. These lines may be used in breeding programs for developing new CMS-lines and F1 hybrids. In addition, these lines (for example, KVV-45) may be used in future investigations on molecular organization of genes encoding structure and/or deposition of kafirins, their cloning and transfer into other sorghum lines by

Gel electrophoresis of the flour subjected to amylolitic enzyme action has demonstrated that starch digestion decreases content of kafirin polymers and reduces subsequent kafirin digestion by pepsin. This finding may explain the reduced nutrient value of sorghum grain, in comparison with other cereals. These data point on the complex mode of interactions of

To test this possibility we used the AS-1a line, which is characterized by ability for development of aposporous embryo sacs and parthenogenetic embryos (Elkonin et al., 2012). Gel electrophoresis showed that kafirin spectrum of this line differs from V-4w (Fig. 7). Two polypeptides were observed in the α1 fraction (α1 and α1-2), the α1-2 was in trace amount, and α1-3 was absent; the α2 fraction did not subdivide into two polypeptides (Fig. 7, lanes 4-6).


Mean data of two replications; data followed by the same letter did not differ significantly (*p*<0.05) according to Duncan Multiple Range Test;

\*, and \*\*\* significant at p<0.05, and p<0.001, respectively.

Table 5. Densitometry of seed storage proteins electrophoretic patterns of F1 A2 Sudzern/Topaz and its parents after treatment with pepsin and/or α-amylase and amyloglucosidase

In order to use this polymorphism for identification of seeds formed via apomixis, the kernels obtained by pollination of emasculated panicles of AS-1a with the pollen of V-4w were split into two parts. The part with an embryo was used to study the phenotypic traits of a seedling. Another part was used in SDS-PAGE to study its kafirin spectrum. In the case of autonomous endosperm development, no V-4w proteins should be found in the kafirin spectra of the kernels yielded maternal seedlings, while in the case of pseudogamous endosperm development, in the electrophretic spectra of these kernels, the SDS-PAGE must reveal V-4w proteins. It was found that kafirin spectra of kernels, which yielded maternal seedlings (Fig. 7, lanes 11,12) did not differ from the spectrum of AS-1a line (Fig. 7, lanes 4-6), while in the spectra of the kernels, which yielded hybrid seedlings the α1-3 protein was clearly distinguished (Fig. 7, lanes 7-10). These data support the results of our cyto-embryological observations of autonomous endosperm development in the AS-1a line (Elkonin et al., 2012) and are in accordance with the literature data on other sorghum lines with apomictic potentials (Rao et al., 1978; Wu et al., 1994; Ping et al., 2004).

Fig. 7. Kafirin spectra of Volzhskoe-4w (lanes 1-3), AS-1а (4-6) and of the kernels, which were set on emasculated panicles of AS-1a pollinated with the Volzhskoe-4w pollen and yielded the F1 hybrid seedlings (7-10) and maternal plants (11-12); М – molecular weight marker (kDa). Gels were stained with AgNO3.
