CELLULAR-RESPONSES OF LEAF EXPLANTS OF COCOS-NUCIFERA L INVITRO
CELLULAR-RESPONSES OF LEAF EXPLANTS OF COCOS-NUCIFERA L INVITRO
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DOI：
10.1007/bf00036118
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发表时间：
1992-03-01
影响因子：
3
通讯作者：
FRANCIS, D
中科院分区：
文献类型：
--
作者：
JESTY, JHF;FRANCIS, D
对椰子 (Cocos nucifera L.) 的叶外植体进行了体外研究，以确定快速的细胞变化是否会导致众所周知的组织培养中椰子细胞的顽抗性。将未成熟叶基部的片段在改良的 Eeuwens 培养基上于 30 摄氏度黑暗中培养。在培养前和培养期间（0至70天）测量有丝分裂指数、核DNA量、细胞和核大小。未成熟椰子叶中不存在细胞分裂的基瓣梯度；有丝分裂指数从未超过 2%，并且与叶子发育既没有位置关系也没有时间关系。此外，绝大多数细胞处于细胞周期的G1期。尽管在70天时S期和G2期的细胞比例有所增加，这与愈伤组织形成率较低相一致，但这种细胞周期模式在培养的大部分时间里都得以维持。无论发育年龄如何，未成熟叶内细胞的核与细胞大小比率都是恒定的。然而，转移到培养基后，细胞尺寸增加，但核尺寸没有增加。我们认为细胞和核大小的这种解偶联破坏了细胞协调，并且是该物种体外顽抗细胞行为的关键因素。
Leaf explants of Cocos nucifera L. (coconut palm) were studied in vitro in order to establish whether or not rapid cellular changes contribute to the well known recalcitrance of coconut cells in tissue culture. Segments from the base of immature leaves were cultured on modified Eeuwens' medium at 30-degrees-C in darkness. The mitotic index, nuclear DNA amounts, cell and nuclear size were measured both before and during culture (from 0 to 70 days). There was no basipetal gradient of cell division in immature coconut leaves; the mitotic index never exceeded 2% and showed neither a positional nor temporal relationship with leaf development. Moreover the vast majority of cells were in G1 of the cell cycle. This cell cycle pattern was maintained for most of the period in culture although at 70 days there was an increase in the proportion of cells in S- and G2-phases consistent with low rates of callus formation. The nuclear:cell size ratio was constant in cells within the immature leaf irrespective of developmental age. However upon transfer to culture media, cell size but not nuclear size increased. We suggest that this uncoupling of cell and nuclear size disrupts cell co-ordination and is a key contributor to recalcitrant cellular behaviour of this species in vitro.