Water deficit inhibits cell division and expression of transcripts involved in cell proliferation and endoreduplication in maize endosperm
Water deficit inhibits cell division and expression of transcripts involved in cell proliferation and endoreduplication in maize endosperm
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DOI：
10.1093/jexbot/52.360.1401
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发表时间：
2001-07-01
影响因子：
6.9
通讯作者：
Flannigan, BA
中科院分区：
文献类型：
--
作者：
Setter, TL;Flannigan, BA
授粉后早期的水分亏缺降低了胚乳细胞的分裂，从而降低了贮藏物质的积累能力。核DNA的有丝分裂后复制（核内复制）也可能在胁迫效应中发挥作用。为了更好地了解细胞增殖和核内复制受水分亏缺影响的程度，研究了玉米胚乳细胞核的数量和大小。通过流式细胞术测定，并定量在细胞周期中具有公认作用的基因的转录水平。授粉后5-13 d的水分亏缺使胚乳细胞分裂率降低90%，9-13 d的[H-3]-TdR掺入量受到抑制。在对照组中，从9-13 DAP开始，参与核内复制的核比例和核DNA含量稳步增加，但水分亏缺最初在9 DAP增加了核内复制的核比例，然后在9-13 DAP停止进一步进入核内复制和S期循环。α-微管蛋白和S期基因产物组蛋白H3和PCNA的转录水平直到13 DAP才受到水分缺乏的影响，而ZmCdc 2（在有丝分裂中具有调节作用的细胞周期蛋白依赖性激酶（CDK））的转录水平从9-13 DAP基本上受到抑制。细胞增殖和相关的过程被抑制在应激事件的初始阶段，而核内复制和相关的S期过程没有被抑制，直到应力更先进。因此，胚乳有丝分裂比核内复制对水分亏缺更敏感。
Water deficit at the early post-pollination stage in cereal grains decreases endosperm cell division and, in turn, decreases the capacity for storage material accumulation. Post-mitotic replication of nuclear DNA (endoreduplication) may also play a role in stress effects. To gain a better understanding of the extent to which cell proliferation and endoreduplication are affected by water deficit, nuclear numbers and size were examined in endosperms of maize (Zea mays L.) by flow cytometry and the transcript levels of genes which have recognized roles in the cell cycle were quantified. Water deficit from 5-13 d after pollination (DAP) decreased the rate of endosperm cell division by 90% and inhibited [H-3]-thymidine incorporation into DNA from 9-13 DAP. The proportion of nuclei engaging in endoreduplication and nuclear DNA content increased steadily from 9-13 DAP in controls, but water deficit initially increased the proportion of endoreduplicating nuclei at 9 DAP, then halted further entry into endoreduplication and S-phase cycling from 9-13 DAP. Transcript levels of alpha -tubulin, and the S-phase gene products histone H3 and PCNA were not affected by water deficit until 13 DAP, whereas those of ZmCdc2, a cyclin dependent kinase (CDK) with regulatory roles in mitosis, were inhibited substantially from 9-13 DAP. Cell proliferation and associated processes were inhibited at initial stages of the stress episode, whereas endoreduplication and associated S-phase processes were not inhibited until the stress was more advanced. It was concluded that endosperm mitosis has greater sensitivity than endoreduplication to water deficit.