II.42 Varied penetration in the maternal streaked mutants in barley.
T. Tsuchiya, Department of Agronomy, Colorado State University, Fort Collins, Colorado 80523, U.S.A.
Streaked mutants are rather common in barley. Behavior of several streaked mutants has been studied by several workers (see Tsuchiya, 1976, BGN 6: 76-77). In this report the varied penetration of the maternally inherited streaked mutants is described. The materials used in this work are listed in Table 1.
Table 1. Maternal streaked mutants used in this experiment.
CSU B15-11.
Yellow streak. Expression of the trait varies from plant to plant.
Some plants are almost green with fine yellow stripe. Yellow streak is
very conspicuous in some plants and very weak in others. Some plants are
almost pure yellow or chlorina type with green stripe. Often pure chlorina
is segregated in the progeny of such plants. Origin of maternal chlorina
may be this kind of maternal stripe mutants.
CSU T2-28.
Expression of the streak character is rather complicated. Many plants
are yellow and/or white streak. Many streaked plants segregate white and/or
yellow streak and albino in their progenies. In one case the segregation
was 3 streak : 11 albino. Others segregate chlorina and albino. A single
plant may show yellow striped and white striped leaves. Even a single leaf
may show yellow stripe and white stripe. In some growing conditions the
streaked trait may not be noticed, because of its weak expression, particularly
in the field.
CSU T12-26
The breeding behavior is complicated in this stock too. In a population
some plants are homozygous for chlorina and others are heterozygous for
albino. Still others segregate white streak and albino. It may be possible
to select two or three strains which are different in their characteristics.
This stock also may have been a source for maternal chlorina.
Breeding behavior of some Mendelian recessive genes for white streaked mutants is variable depending on the genetic backgrounds even if the major gene (wst for example) is the same (Tsuchiya, 1976 ).
Character expression of some mendelian recessive genes for yellow streak is different in different plants. Some plants are almost chlorina type with small green sectors, others show good yellow streaked character from early seedling stage, still others show weak expression of character at later stage of growth (Tsuchiya, 1976 ).
The expression of the streaked characteristics in the maternal streak mutants are similar to the above-mentioned nuclear-gene controlled streaked mutants in some aspects. However, generally the character expression and breeding behavior is more complicated in maternal mutants than nuclear mutants. These specific characteristics of streaked mutants may be used as an indicator in detecting possible maternal streaked mutants in the genetic stock. Ahokas (1976) reported similar results.
References:
Ahokas, H. 1976. Two segregating cytoplasmic mutants of barley. Hereditas (In press).
Tsuchiya, T. 1975. Five more cases of maternal inheritance in barley. BGN 5: 60-62.
Tsuchiya, T. 1976. Variation in the diagnostic character expression in five white streaked mutants in barley. BGN 6: 76-77.
