DNA endoreduplication in maize endosperm cells: the effect of exposure to short-term high temperature
DNA endoreduplication in maize endosperm cells: the effect of exposure to short-term high temperature
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DOI：
10.1046/j.1365-3040.2000.00564.x
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发表时间：
2000-06-01
影响因子：
7.3
通讯作者：
Phillips, RL
中科院分区：
文献类型：
--
作者：
Engelen-Eigles, G;Jones, RJ;Phillips, RL
玉米（Zea mays L, cv, A619 x W64A）胚乳的DNA内复制在授粉后16 ~ 18 d达到高峰，DNA内复制的生理功能尚不清楚，但被认为在玉米籽粒发育中具有重要作用。研究了高温（35℃）处理2、4、6 d对玉米籽粒DNA内复制和发育的影响，并与25℃下的对照籽粒进行了比较，收集了鲜重（FW）、核数、有丝分裂指数和DNA内复制的数据，结果表明高温处理4、6 d会降低玉米胚乳FW和核数。在18 DAP时，高温处理2 d导致FW和核数减少，但对每个胚乳的DNA内重复数和平均DNA含量没有影响，但当高温处理增加到4和6 d时，FW、核数和DNA内重复数逐渐减少，有丝分裂指数峰值较对照推迟。在18 DAP处理4 d时，54.7%的细胞达到3或6℃，而只有41.2%的细胞达到12℃或更高。高温处理6 d后，胚乳FW减少，核数减少，有丝分裂指数峰值延迟。高温处理下的籽粒发生了DNA内复制，虽然强度比对照显著降低，但细胞核DNA含量与籽粒粗重呈高度相关（r = 0.93），说明DNA内复制在决定胚乳粗重中起着重要作用。数据表明，胚乳细胞分裂过程中的高温会显著减少细胞核数，从而对DNA内复制产生负面影响。然而，数据还表明，长时间暴露在高温下会限制有丝分裂细胞进入细胞周期的内复制阶段。
DNA endoreduplication in Zea mays L, (cv, A619 x W64A) endosperm peaks between 16 and 18 d after pollination (DAP), The physiological function of DNA endoreduplication is not known but it is believed to be important in maize kernel development. In the present study, we investigated how 2, 4 or 6 d of high temperature (35 degrees C) affected DNA endoreduplication and maize kernel development in comparison with control kernels grown at 25 degrees C, Data were collected on fresh weight (FW), nuclei number, mitotic index, and DNA endoreduplication, Maize endosperm FW and nuclei number were reduced by exposure to 4 or 6 d of high temperature. At 18 DAP, the 2 d high temperature treatment (HTT) caused a reduction in FW and nuclei number, but had no effect on DNA endoreduplication and average DNA content per endosperm, However, when the exposure to high temperature was increased to 4 or 6 d, FW, nuclei number and the magnitude of DNA endoreduplication were progressively reduced, and the peak mitotic index was delayed compared with the control endosperm. At 18 DAP, the 4 d treatment showed 54.7% of the cells were 3 or 6 C,whereas only 41.2% were 12 C or higher. Six days of high temperature also resulted in a reduction in endosperm FW,nuclei number and a delay in the peak of mitotic index. DNA endoreduplication occurred in the kernels exposed to this treatment, although the magnitude was severely reduced compared with the control kernels, Nuclear DNA content was highly correlated (r = 0.93) with kernel FW,suggesting an important role of DNA endoreduplication in determining endosperm FW,The data suggest that high temperature during endosperm cell division exerted negative effects on DNA endoreduplication by dramatically reducing the nuclei number, leaving fewer nuclei available for DNA endoreduplication, However, the data also suggest that prolonged exposure to high temperature restricts entry of mitotic cells into the endoreduplication phase of the cell cycle.