The mutant gene for spiral neck (spn) was induced in the cultivar: Assahi No. 5 by irradiation (X-ray, 15 Kr) by Tsuchiya (1962). The characteristic of this mutant was described by Tsuchiya (1974). The gene symbol of cu4 for curly 4 was adapted later (Tsuchiya, 1984b).

The gene is inherited as a simple recessive and is characterized by curly roots, wrinkles in the leaves, a spiral or kinky neck, and curly or bent awns (Tsuchiya, 1984a, b) . The results of the genetic study for this mutant was reported as not being associated with chromosome 1, 3, 4, 5, and 6 (Furst, 1983).

In this study, additional data (Table 1) showed 3:1 segregation ratio for normal (+) to curly 4 (cu4). The gene cu4 (or spn) is definitely not associated with chromosome 1, 3, 5, and 6.

For Triplo 4, although the X² value of 5.26 is high for disomic inheritance (3:1), an appreciable number of trisomic plants were homozygous curly 4 mutant. This clearly indicates that the gene for curly 4 is not on the chromosome 4. For Triplo 7, making any conclusion is not adequate because of 2 the small number of plants in F₂population analyzed, although X²(3:1) value of 0.22 was obtained.

In conclusion, it is assumed that the curly 4 gene (cu4) is located on either chromosome 2 or 7, which are now under investigation.

References:

Furst, E. C. 1983. Primary trisomic analysis of three mutant genes in barley. M. S. Thesis, Colorado State Univ., Co.

Tsuchiya, T. 1974. Root character of curly mutants in barley. BGN 4:88-89.

Tsuchiya, T. 1984a. Inheritance of cu4 for curly 4 (spiral neck) mutant in barley. BGN 14:51-52.

Tsuchiya, T. 1984b. BGN 0460, Curly 4, cu4. BGN 14:97.