International Rice Research Institute, PO Box 933, Manila Philippines
Six chlorina mutants have been described in rice (RGN 1, p. 31). We received
seeds of 6 additional chlorina mutants from Dr. R.N. Misra of Central Rice
Research Institute, Cuttack, India (Table 1). Allele tests were made between
the six known chl mutants and the new mutants. They were also crossed with
IR36. As shown in Table 2, all the F\1s\ with IR36 were normal thus showing
that the new mutants are recessive. Data of Table 2 also shows that RGS 347,
RGS 348, RGS 349 and RGS 249 are allelic. Thus RGS 263, RGS 250 and RGS 347
have new chlorina genes. We have designated these mutants as chl-7 (RGS 263),
chl-8 (RGS 250) and chl-9 (RGS 347). As already reported chl-7 was located on
chromosomes 3 (Librojo and Khush 1986). We studied the genetic segregation of
chl-8 and chl-9 in the F\2\ or backcross progenies of all the primary
trisomics. Trisomic ratios were obtained in the F\2\ progenies of Triplo 8 and
chl-8 as well as chl-9 (Table 3). All the other populations segregated in a
digenic manner. Thus chl-8 and chl-9 are located on chromosome 8. Only two
genes, sug and v-8 were known to be on chromosome 8 (Khush et al. 1984). Thus
the location of chl-8 and chl-9 on chromosome 8 is a welcome addition. We have
also located two isozyme loci (Amp-2 and Amp-4) to chromosome 8 (Wu et al.
1988). Thus six genes are now known to be on chromosone 8 and the gene order
and map distances are being determined.
Table 1. Chlorina mutants from Dr. R.N. Misra and parental variety
=============================================================================== Stock No. Parental variety Gene symbol =============================================================================== RGS 263 CR 113-32 chl-7 RGS 250 CH 45 chl-8 RGS 347 CH 45 chl-9 RGS 348 CH 45 chl-9 RGS 349 CH 45 chl-9 RGS 249 CH 45 chl-9 ===============================================================================
Table 3. Segregation ratios for two chlorina genes in the F\2\
generation of primary trisomics of rice
References
Khush, G.S., R.J. Singh, S.C. Sur and A.L. Librojo, 1984. Primary trisomics of rice: origin, morphology, cytology and use in linkage mapping. Genetics 107: 141-163.
Librojo, A.L. and G.S. Khush, 1986. Chromosomal location of some mutant genes through the use of primary trisomics in rice. In Rice Genetics, pp. 249-255. International Rice Research Institute, PO Box 933, Manila, Philippines.
Wu, K.S., J.C. Glaszmann and G.S. Khush, 1988. Chromosomal location of ten isozyme loci in rice (Oryza sativa L.) through trisomic analysis. Biochemical Genetics 26: 303-320.