30. Inheritance of mutant characters induced by gamma-ray irradiation of anther cultures in rice

Itsuro TAKAMURE, Koichl MORI and Toshiro KINOSHITA

Plant Breeding Institute, Faculty of Agriculture, Hokkaido University, Sapporo, 060 Japan



Anthers inoculated on the medium and anther-derived calli were irradiated with acute and chronic gamma-rays with four kinds of doses. It was noted that induction of somaclonal mutants remarkably increased by gamma-irradiation with the dose of 20 kR or 30 kR in chronic gamma-rays (Table 1). Though the



Table 1. Effect of gamma-ray irradiation on anther and anther callus

==============================================================================
Treatment     No. of     No. of M\5\ Lines     Frequency (%) of mutant lines
              M\2\    ======================  ================================
              lines   Normal  mutant  Total   M\2\        M\3\      M\5\
                      (fix.)  (fix.)          mutants     mutants   mutants
                                              /M\2\       /M\2\     /M\2\
==============================================================================
Anther
  0.5 kR        57       0      6      6       36.8        5.3       10.5
  1.0 kR         9       0      2      2       55.6       22.2       22.2
  20  kR        31       0      9      9       61.3       16.1       29.0
  30  kR        13       0      3      3       61.5       38.5       23.1

Anther callus
  0.5 kR        51       1      1      2       29.4        3.9        2.0
  1.0 kR        21       0      3      3       33.3       14.3       14.3
  20  kR        23       0     10     10       78.3       43.5       43.5
  30  kR        30       1     10     11       80.0       50.0       33.3

Anther culture
non-irradiation 36       0      3      3       38.9        8.3        8.3
Control         23       1      0      1       0.0         0.0        0.0
==============================================================================
*Doubled haploid lines produced from diploid plants regenerated from anther
calli (M\1\R\1\ or the 1st generation of mutagenesis and regeneration).
M\2\ - 2nd generation of mutagenesis and regeneration.


Table 2. Comparison of characters between Kitaake and six mutant lines

================================================================================
                                         Character1)  
                      ==========================================================
Strain   Treat.       CL     PL      PN     SL      sw      NS      SF     HP
                    (cm)    (cm)           (mm)     (mm)            (%)  (days)
================================================================================
Kitaake  Control    52.0    14.7    12.1    5.89    3.59    59.6    94.3  87.7
                    (100)  (100)   (100)   (100)   (100)   (100)   (100) (100)
AT-49    30 kR      36.9**  13.3*   23.2**  5.79    3.28**  17.6**  75.4* 86.6
         (Anther)   (68)   (91)    (192)   (98)    (91)    (30)    (80)  (99)

AT-52    30 kR      51.3    14.3    10.6    5.97    3.67*   51.8    89.2* 91.5
         (Anther)   (98)   (97)    (88)    (101)   (102)   (87)    (95)  (104)

AT-127   1.0 kR     48.3     9.9**  13.3    5.37**  3.43    17.8**  87.6  91.8
         (Anther)   (93)   (67)    (110)   (91)    (96)    (30)    (93)  (105)

AT-130   20 kR      50.0    13.7*   16.6*   4.98**  2.87**  77.3*   39.8**112.0*
        (Callus)    (96)   (93)    (137)   (85)    (80)    (130)   (42)  (128)

AT-173   30 kR      32.7**   9.3*    5.8*   5.38*   3.48    21.7**   1.2**92.3
         (Callus)   (63)   (67)    (47)    (91)    (97)    (36)    (1)   (105)

AT-307 (non-irrad.) 48.1    13.0*   12.6    5.88    3.62*   49.3    89.5  87.8
                    (92)   (88)    (104)   (100)    (101)  (83)    (95)  (100)
================================================================================
1) CL: Culm length, PL: Panicle length, PN: Panicle number, SL: Spikelet
length, SW: Spikelet width, NS: Number of spikelets per panicle, SF: Seed
fertility, HP: Heading period.
*, **; Significantly different from Kitaake at the 5% and 1% levels,
       respectively.


Table 3. F\2\ segregation of mutant characters in rice crosses

=============================================================================
Cross        Mutant           F\2\ segregation            Goodness of fit
combination  character        ================  Total   =====================
                               Normal  mutant           X2(3:1)      p
=============================================================================
AT-49xNormal   dwarf             177      56     233      0.12   0.8-0.7
AT-52xNormal   brown leaf spot   268      97     365      0.48   0.5-0.4
AT-127xNormal  short panicle     575     188     763      0.05   0.9-0.8
AT-13OxNormal  small grain       435     117     552      4.26   .05-.01
AT-173xNormal  brittle culm      103      30     133      0.42   0.6-0.5
AT-307xNormal  reduced panicle   831     250    1081      2.02   0.2-0.1
=============================================================================


segregation occurred in the M\2\R\2\ generation, most of the mutant characters were inherited stably from M\3\ to M\5\. Thus, the somaclonal variation was enhanced by the gamma irradiation as pointed out by Novak et al. (1988).

Agronomic characters in six mutant lines (AT-lines) which were selected on the basis of altered phenotype indicated that these lines were different from the original variety, 'Kitaake'. Seed sterility, dwarfness and grain size were frequently altered in AT-lines. It seems that most of the mutant genes exhibit pleiotropic effects on several characters. Genic analyses indicated that most of the mutant characters were due to a single recessive gene. Dwarf mutant with short panicle in AT-49, small brown leaf spots on leaf blades in AT-52, short panicle in AT-127, small grain in AT-130, brittle culm in AT-173 and ruduced spikelets on the panicle tip in AT-307 were governed by single recessive genes, respectively (Table 2, 3).


References

Novak, F.J., S. Daskalov, H. Brunner, M. Nesticky, R. Afza, M. Dolezelova, S. Lucretti, A. Herichova and T. Hermelin, 1988. Somatic embryogenesis in maize and comparison of genetic variability induced by gamma radiation and tissue culture techniques. Plant Breed. 101: 66-79.