Clowes F A L, Wadekar R
Department of P Sciences, University of Oxford, South Parks Road, Oxford OX1 3RA, U.K.
New Phytol. 1988 Mar;108(3):259-262. doi: 10.1111/j.1469-8137.1988.tb04160.x.
Rates of mitosis in each of the four tiers of the cap meristem of primary roots of Zea mays L. were measured at uniform root length by a stathmokinetic method and compared with rates for other regions of the apices in seedlings growing at between 15 and 35 °C. The highest elemental rate of cap cell production in the proximal tier and in the cap meristem as a whole occurs at 26 °C and the proportion of cells supplied by the proximal tier rises from 48%, at 15 °C to 90% at 35 °C. The number of cells in the whole cap and in its meristem decreases with increasing temperature. This is due to the general reduction in the width of root apices with age and growth in length being faster at the higher temperatures. The slimming of the apex is effected by a decline in the proportion of divisions that are longitudinal to the files of cells at the quiescent centre. This is enhanced by a slight but continuous increase in the rate of mitosis in the quiescent centre the higher the temperature (in contrast with the rest of the root whose maximal rate is at 2S °C). The decline results in an increase in the elemental rate for longitudinal divisions in the cap initials from 0.02 to 0.17 cells per cell per day between 15 and 35 °C and a consequent change in the cell pattern in the cap.
采用静止有丝分裂方法，在玉米初生根帽分生组织的四个层级中，于统一根长下测量有丝分裂速率，并与15至35摄氏度下生长的幼苗根尖其他区域的速率进行比较。帽近端层级以及整个帽分生组织中帽细胞产生的最高元素速率出现在26摄氏度，近端层级提供的细胞比例从15摄氏度时的48%上升至35摄氏度时的90%。随着温度升高，整个根帽及其分生组织中的细胞数量减少。这是由于随着根尖年龄增长，根尖宽度普遍减小，且在较高温度下根长度增长更快。根尖变细是由于静止中心处细胞列纵向分裂比例下降所致。随着温度升高（与根的其他部分最大速率出现在25摄氏度相反），静止中心有丝分裂速率轻微但持续增加，这进一步加剧了根尖变细。这种下降导致帽原始细胞纵向分裂的元素速率在15至35摄氏度之间从每天每个细胞0.02个细胞增加到0.17个细胞，从而导致根帽中细胞模式发生变化。
