Hopf N, Plesofsky-Vig N, Brambl R
Department of Plant Biology, University of Minnesota, Saint Paul 55108.
Plant Mol Biol. 1992 Jul;19(4):623-30. doi: 10.1007/BF00026788.
While a heat shock treatment of 40 degrees C or 45 degrees C induced the vegetative tissues of maize to produce the typical heat shock proteins (HSPs), germinating maize pollen exposed to the same temperatures did not synthesize these characteristic HSPs. Comparison of RNA accumulation in shoot and tassel tissue showed that mRNAs for HSP70 and HSP18 increased several-fold, reaching high levels within 1 or 2 hours. At the higher temperature of 45 degrees C these vegetative tissues were blocked in removal of an intron from the HSP70 mRNA precursor, which accumulated to a high level in tassel tissue. In germinating pollen exposed to heat shock, mRNAs for these HSPs were induced but accumulated only to low levels. The stressed pollen maintained high levels of RNA for alpha-tubulin, a representative normal transcript. It is likely that the defective heat shock response of maize pollen is due to inefficient induction of heat shock gene transcription.
虽然40摄氏度或45摄氏度的热激处理能诱导玉米的营养组织产生典型的热激蛋白（HSPs），但暴露于相同温度下的萌发玉米花粉却不合成这些特征性的热激蛋白。对茎和雄穗组织中RNA积累的比较表明，HSP70和HSP18的mRNA增加了几倍，在1或2小时内达到高水平。在45摄氏度的较高温度下，这些营养组织在从HSP70 mRNA前体中去除内含子时受阻，该前体在雄穗组织中积累到高水平。在暴露于热激的萌发花粉中，这些热激蛋白的mRNA被诱导，但仅积累到低水平。受胁迫的花粉维持着高水平的α-微管蛋白RNA，这是一种代表性的正常转录本。玉米花粉有缺陷的热激反应可能是由于热激基因转录的诱导效率低下。
