Two Abelmoschus species, viz., A. manihot (L.) Medik and A. manihot (L.) Medik ssp. manihot, resistant to Okra yellow vein mosaic (YVM) were crossed to A. esculentus cv. 'Pusa Sawani', a susceptible culture. The hybrids were resistant and partially fertile. Segregation pattern for disease reaction in F2, BC1 and subsequent generations of the two crosses revealed that resistance to YVM is controlled by a single dominant gene in each species.

Genetic studies on radiation-induced chlorina and variegated mutants of okra (Abelmoschus esculentus (L.) Moench) revealed the existence of an unstable gene. The normal green color of the leaves is controlled by duplicate genes C1 and C2, either of which produces the green colour. The chlorina plants are C 1 C 1 C 2 C 2. The allele c 1 (v) is dominant to both C 1 and C 2 but is unstable. The homozygote c 1 (v) c 1 (v) c 2 c 2 is a normal green while the heterozygote c i (v) c 1 c 2 c 2 has a variegated phenotype as a result of the mutation of c 1 (v) to c 1 during development. In green plants with a c 1 (v) c{sh1/v}c 2 c 2 genotype, the autonomous mutation of one of the c 1 (v) alleles to c 1 may take place at the pre-meiotic stage. In the variegated genotype (c 1 (v) c 1 c 2 c 2), the mutation of c 1 to c 1 (v) may take place in early ontogeny, thus producing green plants. The allele C 1, when associated with c 1 (v) in a heterozygous condition, mutates to c 1 at the pre-meiotic stage even in the presence of the allele C 2.

No abstract

‘Parbhani Kranti’ (PBNO 57) is an okra [Abelmoschus esculentus (L.) Moench] resistant to yellow vein mosaic (YVM) disease. YVM is the most serious disease of okra in India, and the causative virus is transmitted by the white fly (Bemisia tabaci Gen.). The disease not only reduces yield substantially (10% to 93%) but also affects marketability of the fruits. There is no source of resistance in the cultivated species (2, 7). Some related species are resistant to the YVM disease (1, 8). YVM resistance of A. manihot (L.) Medic., a related wild species, is controlled by a single dominant gene (3).

No abstract