伏令夏橙愈伤组织体细胞胚发生中多胺水平的变化

Changes in Polyamine Levels in Citrus sinensis Osb. cv. Valencia Callus During Somatic Embryogenesis

以继代培养8年的伏令夏橙愈伤组织为材料,研究了不同类型愈伤组织体细胞胚发生能力的差异和多胺水平的变化及两者之间的关系。结果表明,胚性愈伤组织的多胺含量高于非胚性愈伤组织,体细胞胚发生能力与多胺水平呈正相关。体细胞胚发生早期Put含量的增加有利于体细胞胚发生。球形胚大量形成时,Spd达到最高值;球形胚发育后期并有少量心形胚形成时Spm达到峰值。随着倍性的增加,伏令夏橙体细胞胚发生能力降低。精氨酸脱羧酶的活性变化与Put水平呈正相关,表明它是调节伏令夏橙体细胞胚发生中多胺水平的重要因子。

Somatic embryogenetic capability andchanges in polyamine level and their relationship wereanalyzed using the long-term (8 years) subcultured calliof Citrus sinensis Osb. cv. Valencia as materials. Theresults showed that endogenous polyamine contentsin embryogenic calli were higher than those in non-embryogenic calli, and the embryogenetic capabilitywas positively correlated to the levels of endogenouspolyamines (Table 1, Fig.4). When the calli were trans-ferred to a differentiation medium, the putrescine con-tent rapidly increased and reached a peak, then fellgradually (Fig.1). Applying exogenous putrescine raisedthe embryogenesis frequency and endogenous pu-trescine level (Table 2). It indicated that increase inputrescine content at early stage of differentiation pro-moted embryogenesis. With the development of so-matic embryo, spermidine content reached its the high-est level at globular embryo stage (Fig.2), sperminecontent rose and reached a peak at a later stage of globular embryo development (Fig.3). Furthermore,changes of the putrescine, spermidine and sperminecontents during somatic embryogenesis were similarin Valencia calli which had different ploidy levels, buttheir contents decreased following the increasing ofploidy level (Figs.1–3). Changes in arginine decarboxy-lase activity (Fig.6) were positively correlated to thepolyamine levels, which suggest that the later is a keyfactor in regulating the polyamine levels during so-matic embryogenesis in citrus plants.