32. Use of primary trisomics of rice for associating linkage groups with respective chromosomes


Gurdev S. KHUSH, R. J. SINGH, S. C. SUR and A. L. LIBROJO

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


Twelve linkage groups corresponding to the haploid chromosome number of rice were suggested by Nagao and Takahashi (1963). However, these linkage groups have not been associated with the cytologically identifiable chromosomes and their independence has not been tested. We established all the twelve possible primary trisomics in the background of a disease and insect resistanct and widely grown indica variety, IR36. The extra chromosome of each of the trisomics was identified at pachytene stage of meiosis following the numbering system of Shastry, Ranga Rao and Misra (1960). Accoridng to this system the longest pachytene chromosome was numbered as 1 and shortest as 12. We studied the segregation of 22 marker genes in the trisomic progenies. In all we tested 120 out of 264 possible combinations involving 22 genes and 12 trisomics. On the basis of modified trisomic ratio technique we were able to identify marker genes for all the 12 chromosomes. Three linkage groups (VI, IX, and XII) were associated with chromosome 5 and linkage groups VII and V were associated with chromosome 9. New linkage groups for chromosomes 6, 8 and 10 were established. The relationships between the chromosome numbering systems of Shastry, Ranga Rao and Misra (1960), Nishimura (1961), Kurata and Omura (1978) and the linkage groups of Nagao and Takahashi (1963) are shown in Table 1. The table also shows the relationships between our trisomics and those of lwata and Omura (1975). Detailed paper on these investigations will appear in volume 106 of Genetics.



Table 1. Relationships between various systems of numbering chromosomes, trisomics, linkage groups, and marker genes of rice


=============================================================================
          Chromosomes              Trisomics    Linkage
                                                groups
============================   ==============
Shastry,              Kurata           Iwata    Nagao         Maker
Ranga Rao  Nishimura,  and     This     and     and           genes
and Misra   (1961)    Omura    study   Omura   Takahashi
(1960)                (1978)           (1975)   (1963)
=============================================================================
1             3        K1*      1        O*      III     eg. lax
2             8        K2*      2        N*       X      tri
3             6        K6       3        B        I      wx,ws
4             5        K3*      4        M*      XI      bc\1\,ch\1\,dl
5             2        K9       5        L    VI,IX,XII  gh\1\,nl\1\,gl\1\
6             4        K5       6        A        -      spl\1\, rl\1\
7            10        K11      7        F       IV      g
8            12        K7       8        D        -      v\8\,su
9             1        K1O      9        H     VII,V     dp\2\,drp\2\,I-Bf
10            7        K12     10        C        -      pgl,fl
              9        K8      11        G       VII     la, z\2\
12           11        K4      12        E       II      lg, Pl
=============================================================================
*added by editor as per lwata, Satoh and Omura (No. 34)

References

Iwata, N., and T. Omura, 1975. Studies on the trisomics in rice plants (Oryza sativa L.). III. Relation between trisomics and genetic linkage groups. Jpn. J. Breed. 25: 363-368.

Kurata, N. and T. Omura, 1978. Karyotype analysis in rice. I. A new method for identifying all chromosome pairs. Jpn. J. Genet. 53: 251-255.

Nagao, S., and M. Takahashi, 1963. Genetical studies on rice plant. XXVII. Trial construction of twelve linkage groups of Japanese rice. J. Fac. Agric. Hokkaido Univ. 53: 72-130.

Nishimura, Y. 1961. Studies on the reciprocal translocations in rice and barley. Bull. Natl. Int. Agric. Sci. Jpn. Ser. D 9: 171-235.

Shastry, S. V. S., D. R. Ranga Rao and R. N. Misra, 1960. Pachytene analysis in Oryza. I. Chromosome morphology in Oryza sativa. Ind. J. Genet. Breed. 20: 15-21.