20. New mutations at old loci


Gurdev S. KHUSH and A. L. LIBROJO

International Rice Research Institute, P.O. Box 933, Manila, Philippines


The lazy (la) mutant of rice is a well known marker of linkage group VIII. During last few years, we obtained five new lazy mutants which were induced through mutagenic treatments in different varieties of rice by three scientists (Table 1). These five lazy mutants were crossed with RGS 14 (our lazy tester stock) as well as with IR36 (non-lazy cultivar). The five F\1\s with IR36 were normal indicating that all the five new lazy mutants are recessive. All five F\1\s with RGS14, however, were lazy, thereby showing that the new mutations occurred at the previously known la locus.


Table 1. New lazy mutants of rice tested for allelic relationships with la (RGS 14)


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RGS No.  Parent variety             Muitant obtained from
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54       Balilla (Mutant No. 19)    R. Marie, INRA France
56       Cesariot (Mutant No. 28)   R. Marie, INRA France
73       Americano (Mutant No. 16)  R. Marie, INRA France
234      Norin 18                   K. Pavithran, Calicut, India
259      CR115-32                   R. N. Misra, CRRI, India
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