Department of Genetics, University of Delhi, South Campus, Benito Juarez Road, New Delhi 110021, India
Plant Physiol. 1998 Feb 1;116(2):617-25. doi: 10.1104/pp.116.2.617.
Four critical stages of embryogenesis, including callus induction, cellular acquisition of morphogenetic competence, expression of embryogenic program, and development and maturation of somatic embryos during somatic embryogenesis from leaf discs of eggplant (Solanum melongena L.), were identified by scanning electron microscopy. Temporal changes in arginine decarboxylase (ADC) activity and polyamines (PAs) during critical stages of embryogenesis revealed that high levels of PAs (especially putrescine [PUT]), due to higher ADC activity in discs from the apical region (with high embryogenic capacity) than from the basal region of the leaf (with poor embryogenic capacity), were correlated with differential embryogenesis response. Kinetic studies of the up- and down-regulation of embryogenesis revealed that PUT and difluoromethylarginine pretreatments were most effective before the onset of embryogenesis. Basal discs pretreated with PUT for 4 to 7 d showed improved embryogenesis that was comparable to apical discs. PA content at various critical steps in embryogenesis from basal discs were found to be comparable to that of apical discs following adjustments of cellular PA content by PUT. In contrast, pretreatment of apical discs with difluoromethylarginine for 3 d significantly reduced ADC activity, cellular PA content, and embryogenesis to levels that were comparable to basal discs. Discs from the basal region of leaves treated with PUT for 3 d during the identified stages of embryogenesis improved their embryogenic potential.
通过扫描电子显微镜确定了茄子（Solanum melongena L.）叶片圆盘体细胞胚胎发生过程中胚胎发育的四个关键阶段，包括愈伤组织诱导、细胞获得形态发生能力、胚胎发生程序的表达以及体细胞胚胎的发育和成熟。胚胎发育关键阶段精氨酸脱羧酶（ADC）活性和多胺（PAs）的时间变化表明，由于来自叶片顶端区域（胚胎发生能力高）的圆盘比来自叶片基部区域（胚胎发生能力差）的圆盘具有更高的ADC活性，高水平的PAs（尤其是腐胺[PUT]）与不同的胚胎发生反应相关。胚胎发生上调和下调的动力学研究表明，PUT和二氟甲基精氨酸预处理在胚胎发生开始前最有效。用PUT预处理4至7天的基部圆盘显示出与顶端圆盘相当的胚胎发生改善。在用PUT调整细胞PA含量后，发现基部圆盘胚胎发生各个关键步骤的PA含量与顶端圆盘相当。相反，用二氟甲基精氨酸预处理顶端圆盘3天显著降低了ADC活性、细胞PA含量和胚胎发生率，使其达到与基部圆盘相当的水平。在确定的胚胎发育阶段用PUT处理3天的叶片基部区域圆盘提高了它们的胚胎发生潜力。
