Klein R R, Mullet J E
Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843-2128.
J Biol Chem. 1990 Feb 5;265(4):1895-902.
Transcription and Northern dot blot analyses were used to determine the relationship between light-induced changes in RNA levels and transcription in barley and maize plastids. Overall plastid transcription activity is near maximum and largely light independent in apical sections of 4.5-day-old dark-grown barley seedings. With continued development in the dark, transcription activity in barley plastids declined precipitously, but transcription could be reactivated if plants were illuminated. Illumination of 8-day-old dark-grown barley seedlings increased the transcription of psbA, rbcL, and 16 S rDNA; however, the stimulation of psbA transcription was 2-4-fold more than rbcL or 16 S rDNA. Differential enhancement of psbA transcription occurred when 4.5- or 8-day-old dark-grown seedlings were illuminated, and the influence persisted in plants illuminated for 72 h. Illumination of 8-day-old dark-grown barley caused an increase in psbA and rbcL mRNA levels, but the increase in psbA mRNA was greater than that of rbcL. Similarly, illumination of 9-day-old dark-grown maize increased plastid transcription activity and the levels of psbA and rbcL mRNA. These results indicate that light can modulate overall plastid transcription activity and differentially stimulate the transcription of genes including psbA.
转录分析和Northern斑点杂交分析被用于确定大麦和玉米质体中光诱导的RNA水平变化与转录之间的关系。在4.5天大的黑暗生长大麦幼苗的顶端部分，整体质体转录活性接近最大值，且在很大程度上与光照无关。随着在黑暗中持续发育，大麦质体中的转录活性急剧下降，但如果对植株进行光照处理，转录活性可以重新激活。对8天大的黑暗生长大麦幼苗进行光照处理可增加psbA、rbcL和16S rDNA的转录；然而，psbA转录的刺激程度比rbcL或16S rDNA高2至4倍。当对4.5天或8天大的黑暗生长幼苗进行光照处理时，psbA转录出现差异增强，且这种影响在光照72小时的植株中持续存在。对8天大的黑暗生长大麦进行光照处理会导致psbA和rbcL mRNA水平增加，但psbA mRNA的增加幅度大于rbcL。同样，对9天大的黑暗生长玉米进行光照处理会增加质体转录活性以及psbA和rbcL mRNA的水平。这些结果表明，光可以调节整体质体转录活性，并差异刺激包括psbA在内的基因的转录。
