Penetration and Expression of the npnd Gene of Voltinism in F1, F2 and BCP Hybrids between Monobivoltine and Polyvoltine Tropical Strain of Silkworm (Bombyx mori L.)

P. TZENOV, Y. LAZAROV and Y. NACHEVA

Sericultural Experiment Station, BG-3000 Vratza, Bulgaria

Abstract

TZENOV, P., Y. LAZAROV and Y. NACHEVA, 2000. Penetration and expression of the npnd gene of voltinism in F1, F2 and BCP hybrids between monobivoltine and polyvoltine tropical strain of silkworm (Bombyx mori L.). Bulg. J. Agric. Sci., 6: 579-582

Studies were carried out at the Sericultural Experiment Station on the penetration and expression of the gene of voltinism npnd (nonpigmented and nondiapaused egg) in F1, F2 and BCP hybrids between the monobivoltine strain Super 1 and polyvoltine tropical strain Bonde 517. Egg incubation and rearing of hybrids and pure strains were carried out under a regime, provoking laying of nonpigmented and nondiapaused eggs.
The penetration of npnd gene (percent of layings with manifestation of npnd gene) in the tropical polyvoltine strain Bonde 517 was 90.10% and in the monobivoltine strain Super 1 only 27.18%. The tropical strain Bonde 517 demonstrated also higher gene expression (percent of nonpigmented and nondiapaused eggs per laying) 57.50% vs. 43.16% for Super 1 strain. The inheritance of the npnd gene penetration and expression in F1 is intermediate. In backcrosses, npnd gene penetration is higher in the case of domination of the tropical strain blood.

Key words: gene penetration, gene expression, silkworm, monobivoltine tropical strain, polyvoltine tropical strain