**4. Endosperm texture in plants with genetic construct for RNA silencing of the γ‐kafirin gene**

It is known that one of the consequences of silencing of γ‐prolamins in maize and sorghum is a disruption of the formation of the vitreous layer of the endosperm. In previously obtained transgenic sorghum lines with genetic constructs for γ‐kafirin silencing [24, 26, 27], as well as in the mutant with high digestibility [37], the kernels had a floury endosperm type. In trans‐ genic maize plants, silencing of γ‐zein also resulted in reduction of the vitreous layer and the formation of floury endosperm that suggests its role in interaction with starch granules and in the formation of the vitreous endosperm [36]. In this connection, we paid special attention to the endosperm texture in the kernels of our transgenic plants.

Careful examination of the kernels developed on panicles of T<sup>1</sup> plants obtained in our experi‐ ments revealed three plants, #94‐3, #94‐4 and #94‐6, in which the kernels with almost floury endosperm were found (**Figure 7A**) [28]. Such kernels clearly differed from those of the origi‐ nal non‐transgenic line, which have a thick vitreous layer (**Figure 7B**). The amount of such kernels varied in different panicles of one and the same T<sup>1</sup> plants. For example, in T1 plant, #94‐2, all kernels developed on its first panicle did not express floury phenotype, although kernels on its second panicle had either almost floury or modified structure of endosperm. In such kernels, the vitreous layer was significantly reduced and developed as sectors or blurs surrounded by floury endosperm (**Figure 7C**–**E**). Remarkably, these kernels resemble the ker‐ nels of recombinant sorghum lines obtained by hybridization of highly digestible mutant with floury endosperm (*hdhl*) with ordinary sorghum lines with low protein digestibility and vitre‐ ous endosperm [38]. Formation of this endosperm type in our transgenic plants apparently reflects peculiarities of expression of inserted genetic construct during kernel development.

Modified endosperm type of plant #94‐2 inherited for three generations and was observed in Т2 and T3 families (94‐2‐04; 94‐2‐05 and 94‐2‐11) characterized by high *in vitro* protein digest‐ ibility (see Section 5), although kernels with thin or irregularly developed vitreous endosperm (**Figure 7F**–**H**) also formed in panicles of plants from these families. The plants from T2 and T3 families from the progeny #94‐3 (94‐3‐04; 94‐3‐08) had both modified, irregularly developed and normal vitreous endosperm types.

No variation of endosperm type was observed in the kernels developed in other PCR‐positive T1 plants, #94‐1 and #94‐5.

**Figure 7.** Cross sections of kernels with different types of endosperm of transgenic sorghum plants with genetic construct for silencing of the γ‐kafirin gene. (A) Kernel with floury endosperm (Т<sup>3</sup> 94‐2‐05‐1); (B) kernel of original non‐transgenic line Zheltozernoe 10 with thick vitreous endosperm (marked by arrows); (C–E) modified endosperm type with blurs and sectors of vitreous endosperm (T2 94‐2‐05, T2 94‐2‐04, T1 94‐6, respectively); (F–H) irregularly developed vitreous endosperm (T2 94‐3‐08; T3 94‐2‐05‐2; T3 94‐2‐11‐2, respectively). Bar = 1 mm.
