番茄叶组织培养中愈伤组织形成和器官发生的细胞学和微形态学研究

HISTOCYTOLOGICAL AND MICROMORPHOLOGlCAL OBSERVATION OF CALLUS FORMATION AND ORGANOGENESIS OF TOMATO LEAF TISSUE CULTURED IN VITRO

以番茄叶外植体为材料,研究了不同的生长素和细胞分裂素及其浓度配比对叶外植体培养行为的影响;同时,利用细胞学和扫描电子显微镜技术观察了愈伤组织形成和器官发生过程。结果表明,不同种类及浓度配比的生长素和细胞分裂素直接影响愈伤组织的物理状态、大小和形成的速度以及器官分化的频率和速度。叶外植体切口处的叶肉细胞,维管薄壁细胞和维管束上方的少数叶肉细胞首先启动脱分化而开始分裂,这些细胞的活跃分裂和分化导致在外植体表层形成由薄壁细胞、维管组织和无分化状态的表层分生细胞团组成的愈伤组织。而不定芽则通过愈伤组织的薄壁细胞再次脱分化和再分化活动而形成,为“外起源”。认为存在由植物激素决定的“无分化活性”和“有分化活性”二种性质的愈伤组织。

Leaf explants of tomato were used to study the effects of auxin and cytokinin and their combinations on culture behavior of the leaf tissue. Meanwhile, the processes of callus formation and organogenesis were observed by means of cytological and scanning electron microscopic techniques.It was found that the physical texture, size and formation rate of callus, and the frequency and rate of organogenesis were controled by the kinds and combinations of auxin and cytokinin added in the media directly. It was the mesophyll cells near the cut edges, vascular parenchyma and in few case the mesophyll cells above the vascular bundle of the explants that initiated to dedifferentiate to be meriste-matic cells, the active division and diffrentiation of these cells resulted in the formation of callus which consisted of parenchyma, vascular tissue and non-differentiation surface meristemoids. Adventitious buds came from the re-dedifferentiation and redifferentiation activities of the parenchyma of the callus, and were 'external origin'. It was suggested that there existed two kinds of plant hormone-dependent calli, namely, 'differntiation-inactive callus' and 'differentiation-active callus'.