BGN 9: Barley mutants resistant to loose smut Ustilago nuda (Jens.) Rostr. BARLEY GENETICS NEWSLETTER, VOL. 9, II. RESEARCH NOTES
Buivids, pp. 15-16

II. 7. Barley mutants resistant to loose smut Ustilago nuda (Jens.) Rostr.

K. Buivids, Latvian Academy of Sciences, Institute of Biology, 229021, USSR. "R"

We have not stated in literature any data about obtaining barley mutants resistant to loose smut Ustilago nuda (Jens.) Rostr.

The aim of the work was to obtain lines of variety "Maja" with induced resistance to loose smut Ustilago nuda (Jens.) Rostr. by the experimental mutagenesis. Dry seeds of barley were treated with 0.01% solution of N-nitrosomethylurea (NMU) for 12 hrs at 20°C. After treatment the seeds were washed under tap water for 5 hrs at 12°C.

The experiments were begun in summer of 1974 when 900 M3 families (M3 family - progenies of separate M2 plants) were inoculated by the help of improved Moore's (1936) vacuum method, 12-14 ears were taken from each family. A mixture of ecotypes of loose smut, both virulent and avirulent to variety Trebi, were taken for inoculation. Four cycles of inoculation and selection (M4-M7) were carried out by us. The resistance of 700 untreated families from the variety "Maja" was tested in three following generations as a control. No plants resistant to loose smut have been stated among them; there were 79-93% of smutted plants in the control families. Two highly resistant to loose smut (no smutted plants) and three moderately resistant (to 10% of smutted plants) families M7 generation have been stated under the treatment of NMU. The number of resistant families is 0.55% from all the tested ones in M3.

Table l. Number of barley families resistant to loose smut obtained  from plants treated with NMU.

Decrease in the number of resistant families in the first following generations of selection can be explained by their heterozygosity for resistance. Evidently the induced mutations of resistance are dominant. In addition, the stating of resistant plants in separate tests is difficult due to insufficient efficiency of infection that is proved by an incomplete manifestation of induced control plants.

Reference:

Moore, M.B. 1936. Phytopathology 2:103.

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