43. Somaclonal variation of rice calli-clones regenerated after different periods of

callus culture

H. watanabe, C. matsukura R. ishikawa, T. harada and M. niizeki

1 ) Faculty of Agriculture, Hirosaki University, Hirosaki 036. Japan

2) Bioscience Center, Nagoya University, Chikusa, Nagoya 464-01, Japan

Variations arisen from cell culture are called somaclonal variation (Larkin and Scowcroft 1981). We have been investigating how somaclonal variations occur and what kinds of variations are produced by the cell culture. Seeds of Oryza sativa L. cv. Akihikari were used to induce calli and to culture during different periods. Two plant populations regenerated from four (short) and seven (long) months old calli were named as Aki-C and Aki-E, respectively. Regenerated plants were defined as R0 generation. Next generation after self fertilization from R0 plants was called as Rl in this experiment. Although control population generated from seeds without any culture did not show any variations, several kinds of induced variations were classified as, 1) albino, 2) xantha, stripe, and alboviridis, 3) dwarf, 4) variations for seed fertility, and 5) variations for days to heading. The genetic analyses were carried out by using R0 and Rl generations. Significant differences in variant frequencies were found between short term culture (RIC) and long term culture (RIE) (Table 1). The chlorophyll variants governed by a recessive gene or genes were detected in three among 37 lines (8.1%) and nine among 22 lines (40.9%) in RIC and RIE populations, respectively. All of those variations were due to changes in nuclear genes because most of their segregation in Rl

Table 1. Segregation of chlorophyll mutations found in RIC (37 line) and RIE (22

line). Goodness of fit was examined by chi-square (1:3) test

Rl line

Albino Xantha

Stripe Alboviridis

Total

X^2(l:3)'

P

RIC-9

8

45

0.90

0.50-0.25

RIC-32

10

40

0.03

0.90-0.75

RIC-36

5

40

2.70

0.25-0.10

RIE-3

2

20

1.67

0.25-0.10

RIE-10

1

30

6.40

0.025-0.010

RIE-11

4

40

4.03

0.05-0.025

RIE-14

5

31

0.87

0.50-0.25

RIE-14

2

31

4.74

0.05-0.025

RIE-17

1

19

2.96

0.10-0.05

RIE-25

5

27

0.31

0.75-0.50

RIE-29

9

37

0.01

>0.90

RIE-30

18

60

0.55

0.50-0.25

RIE-30

3

60

11.58

<0.005

RIE-48 5

11

56

0.60

0.50-0.25

1: When chi-square showed unfitness for 1:3 ratio, 1:15 ratio, was examied. Those cases showed fitness to 1:15.

146 Rice Genetics Newsletter Vol. 13

Table 2. The comparison of variations for seven traits between R1C, R1E populations and control

CL(cm)

HD(day)

PL(cm)

SPP

SF in P

PF in G

SF in G

R1C

89.4±4.86a

117.8±3.25a

18.7±1.38a

140±23.4a

70.0 + 7.32a

68.5±12.5a

65.6 ± 15.6a

RIE

84.7 ± 7.58b

118.3±2.52b

17.9± 1.39b

135±26.1b

66.8±10.1b

69.4 ± 16.2a

59.0±17.2a

Control

92.5 ± 3.50c

118.2±2.17a

19.6±1.04c

172±23.4c

74.8 ± 4.49c

78.5 ± 2.59b

75.3±5.33b

CL: culm length, HD: days to heading, PL: panicle length, SPP: the number of spiklets per panicle. SF:

seed fertility, PF: pollen ferility, in P: in paddy field, in G: in a greenhouse.

The numerical value shows mean ± S.D.

The small letter indicates no significant difference among respective means according to new multiple range test at 5% level.

lines satisfied the 1:3 ratio (abnormal to normal) due to a single recessive gene. Otherwise, 1:15 ratio was also expected when the chi-square test indicated unfitness to 1:3 ratio. Table 2 shows the comparison of seven quantitative traits among three (RIC, R1E and control) populations derived from different culture periods. It is noted that the R1E occurred more variations than those of R1C. It is possible that the cell culture would affect variability concerning both qualitative and quantitative characters and long duration of culture is more effective to induce genetic variations.

References

Larkin, P.J. and W.R. Scowcroft, 1981. Somaclonal variation - a novel source of variability from cell cultures

for plant improvement. TheorAppl Genet 60: 197-214.