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I. Research Notes
Necrosis genes in Triticum macha, T.
spelta and T. vavilovi1)
K. TSUNEWAKI
Laboratory of Genetics, Faculty of Agriculture, Kyoto University, Kyoto,
Japan
Distribution of necrosis and chlorosis genes was investigated using about
120 varieties (or strains) of Triticum macha, T. spelta
and T. vavilovi; strains of the former species were obtained from
Dr. L. L. DEKAPRELEVICH, while those of the latter two were from Max-Planck
Institute. Their helps are greatly appreciated.
All varieties were crossed to three testers, Jones Fife, Prelude and Macha,
and their F1 phenotypes were observed as to necrosis and chlorosis.
Based on this observation, their genotype formulae were determined, that
are given in Table 1.
As already reported (TSUNEWAKI and HORI 1967), Asian and Western populations
of T. aestivum are remarkably different from each other as to the
frequencies of Ne1 and Ne2 genes;
the former is prevalent in Asian countries, while the latter is found
frequently in Western countries. Both strains of Iranian spelta
(Nos. 3929 and 3930) carried Ne1, and on the other hand,
60% of European spelta varieties had Ne2: Differentiation
of T. spelta into the two population types is evident. T. vavilovi
can be included into Asian type spelt from its necrosis genotype.
T. macha is distinctly different from other 6x species by having
Ch1 gene at a very high frequency (85%, contrasting
to 0.0% in other species). Since all other 6x wheat species contain Ch2
gene at high frequencies (95% or more), hybrid chlorosis caused by these
genes forms a strong isolation barrier between T. macha and other
6x species. Hybridization between an Asian type aestivum and a
Ch1-carrying spelt emmer, and a consequent introgression
of the Ch1 gene to hexaploid level seem to have resulted
in the origin of T. macha.
(Received October 14,1968)
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