The effect of cool-pretreatment on the isolated microspore culture and the free amino acid change of anthers in Japonica rice ( Oryza sativa L)

Abstract

Summary The effect of cool-pretreatment of panicles on the isolated microspore culture and the change in proportion of amino acids in anthers were investigated in japonica rice, and the relationship between free amino acid change and culture response of isolated microspore was suveyed. Cool-pretreatment of panicles for 12–35 days led to an increase of total free amino acid content and the change in proportion of 12 free amino acids. The contents of aspartic acid, threonine, serine, histidine and arginine were increased while the other 7 amino acids, i.e. phenylalanine, glycine, alanine, valine, methionine, leucine, and tyrosine, were decreased. It seemed that 12 days of cool-pretreatment at 6 ± 1 °C were necessary for callusing. High callus formation frequencies were obtained in the cool-pretreatment for 17 to 27 days; the plating 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 frequencies were 1.8%, 1.9%, and 3.4%, respectively. However, cool-pretreatment longer than 27 days affected callus initiation and plantlet regeneration.