杨树叶薄层培养中不定芽形态发生的细胞组织学研究

将杂种杨树(Populus nigra var.betulifolia×P.trichocarpe)NE299叶主脉用振动切片机横切成400μm或800μm的薄切片,培养在附加0.2mg/L BA和0.01mg/L NAA的木本植物培养基上。培养后,位于主脉维管束两侧中上部的维管束鞘薄壁细胞首先启动分裂。几乎同时,与其邻接的一些栅栏组织细胞也分裂,并很快形成胚性分生细胞团。主脉的愈伤组织主要由维管束鞘薄壁细胞,以及与其邻接的一些栅栏组织细胞和韧皮部的薄壁细胞分裂而来。不定芽通常发生在愈伤组织的周边区,也可以起源于维管组织结节(vascular nodules)周围的形成层状细胞。侧脉的维管束鞘细胞分裂活动很强,可不经愈伤组织直接长成不定芽。杨树叶主脉处的维管束鞘薄壁细胞在与叶肉组织相邻接的细胞中,通常含有少量较小的叶绿体,而位于背腹面的细胞中含有贮藏的淀粉。对形态发生的特定部位及其细胞进行了讨论。

CYTOHISTOLOGICAL STUDY ON MORPHOGENESIS OF THE ADVENTITIOUS BUD IN THE IN VITRO CULTURE OF MICRO-CROSS SECTIONED LEAF MIDVEINS FROM HYBRID POPULUS

Micro-cross sections (MCS) of midveins of leaves from hybrid Popidus (P. nigra var. betulifolia x P. trichocarpe) NE 299 were used for studying the adventitious bud formation in vitro . MCS of 400 fan or 800 m in thickness were cut with a vibrating microstome (Lancer Vibratome, model 1000) and cultured in woody plant medium (WPM) supplemented with 0.2 mg/L BA and 0.01 mg/L NAA. Then the division of some parenchyma cells located on each side of the vascular cylinder and connected with the palisade tissue (i.e. adaxial side) were initiated. At the same time the palisade tissue connected with vascular bundles also began to divide and then formed the embryonic meristematic packed cells. The origin of the midvein calli developed mainly from the vascular cylinder, the palisade tissues and the phloem parenchyma cells. Adventitious buds were generally formed on the peripheral parts of the calli, also originated from the cambium-like cells surrounded by the vascular nodules. The parenchymatous bundle sheath of the lateral veins had much higher capacity of division and grew directly into the adventitious buds with no callus phase. Observing the parenchyma cells of the vascular cylinder on the midvein, it was shown that the cells adjacent to the mesophyll cells usually contained little smaller chloroplasts while those on both abaxial and adaxial side contained stored starch granules. The defined sites and the specific cell potential in morphogenesis are discussed.