43. Effect of a chemical hybridization agent HGR-626 on the plant regeneration after anther culture

Koji UKAI and Yuzo FUTSUHARA

Faculty of Agriculture, Nagoya University, Chikusa-ku, Nagoya, 464-01 Japan

The significance of anther culture in plant breeding depends largely on the possibility of whether a higher frequency of plant regeneration can be obtained. Picard et al. (1987) suggested that any substance altering the sex balance could enhance haploid production.

Using a rice cultivar, Nipponbare, the present study was conducted to clarify the effect of HGR-626 (=RH-531) (Sodium-1-(p-chlorophenyl)-1, 2-dihydro-4, 6-dimethyl-2-oxo-nicotinate) which acts as a gametocide or chemical hybridization agent in rice (Perez et al. 1973) on the plant regeneration by anther culture.

Two different doses, 10 ppm and 30 ppm of aqueous solution of HGR-626 were sprayed on the leaves and stems of the plants at the following two stages: 1) spikelet primordium differentiation and 2) meiosis. Following the cold treatment (10°C for 10 days) of anthers at the mid-uninucleate microspore stage, they were cultured on the N6 medium suppleniented with NAA (3 mg/1) and kinetin (0.3 mg/1). The ratios of callus formation and plant regeneration were evaluated 30 days and 45 days after incubation, respectively.

As shown in Table 1, remarkable enhancement in both callus formation and plant regeneration were detected when treated with 10 ppm of HGR-626 at meiosis stage. On the other hand, HGR-626 showed an inhibitive effect when treated at spikelet primordium differentiation stage. This result indicates that the application of HGR-626 at meiosis stage is effective in obtaining haploid plants by anther culture.

  
Table 1. Effect of HGR-626 on callus formation and plant regeneration by
anther culture
===============================================================================
                                       Spikelet primordium     Meiosis
Item of observation   Control          differentiation
                                       ____________________  __________________
                      (No tratement)    10 ppm  30 ppm         10 ppm  30 ppm
===============================================================================
No.of anthers cultured            90       90      90            90       90
No.of anthers producing calli1)   17(18.9)  0       0            33(36.7)  0
No.of green spots2)                6(0.35)  0       0            70(2.12)  0
No.of roots2)                     15(0.88)  0       0            48(1.45)  0
No.of shoots2)                     2(0.11)  0       0            27(0.82)  0
===============================================================================
1)Figures in parentheses indicate No. of anthers producing calli/no. of
anthers cultured (%)
2)Figures in parentheses indicate No. of regenerated organs/callus

References

Perez, A. T., T. T. Chang, H. M. Beachell, B. S. Vergara and A. P. Marciano, 1973. Induction of male sterility in rice with ethrel and RH-531. SABRAO Newsletter 5: 133-139.

Picard, E., C. Hours, S. Gregoire, T. H. Phan and J. P. Meunier, 1987. Significant improvement of androgenetic haploid and doubled haploid induction from wheat plants treated with a chemical hybridization agent. Theor. Appl. Genet. 74: 289-297.