THE EFFECT OF COOL-PRETREATMENT ON THE ISOLATED MICROSPORE CULTURE AND THE FREE AMINO-ACID CHANGE OF ANTHERS IN JAPONICA RICE (ORYZA-SATIVAL)

The effect of cool-pretreatment of panicles on the isolated microspore culture and the change in proportion of amino acids in anthers were i nvestigated in japonica rice, and the relationship between free amino acid change and culture response of isolated microspore was suveyed. C ool-pretreatment of panicles For 12-35 days led to an increase of tota l free amino acid content and the change in proportion of 12 free amin o acids. The contents of aspartic acid, threonine, serine, histidine a nd arginine were increased while the other 7 amino acids, i.e. phenyla lanine, glycine, alanine, valine, methionine, leucine, and tyrosine, w ere decreased. It seemed that 12 days of cool-pretreatment at 6 +/- 1 degrees C were necessary for callusing. High callus formation frequenc ies were obtained in the cool-pretreatment for 17 to 27 days; the plat ing efficiencies of 17, 22, and 27 days of cool-pretreatment were 1.17 , 1.20, and 1.72 calli per anther, and green plantlet regeneration fre quencies were 1.8 %, 1.9 %, and 3.4 %, respectively However, cool-pret reatment longer than 27 days affected callus initiation and plantlet r egeneration.