摘要
本文以一种C4植物——黍子(Panicum miliaceum)为材料,在白光、红光、蓝光、远红光和黑暗5种不同条件下培养黍子幼苗,叶片采收后用于叶绿素积累、叶绿体吸收光谱、叶绿体低温荧光发射光谱和高分子量cpRNA积累的测定以及psbA基因的Northern Blot分析。结果表明:白光、红光和蓝光下生长的黍子,它们的叶绿体都有功能完善的光合系统;而远红光下生长的黍子,已有光系统Ⅱ的发射峰,只是强度和波长都与白光、红光和蓝光下的有所不同;不同光质促进叶绿素积累和高分子量cpRNA积累的效率是平行的,其中红光较蓝光和远红光有效,而复合光(白光)的作用效果最好。当以白光诱导的积累量为100％时,可以分别求出不同光质诱导叶绿素积累和高分子量cpRNA积累的相对量,结果表明,高分子量cpRNA的积累对光的依赖性要比叶绿素积累对光的依赖性大得多。psbA基因的Northern Blot分析表明,不同光质下psbA转录物的积累与高分子量cpRNA的积累是一致的。据此我们推测,在黍子叶绿体的光诱导发育过程中,psbA的转录过程可能不受光信号的直接调控,而是受叶绿体整体发育状态的控制。
The leaves from 7 day old broomcorn millet seedlings grown at 25℃ underincandescent light, blue light, red light, far red light and dark were harvested fordetermining the contents of chlorophyll, the absorptive spectra and the fluorescenceemission spectra of chloroplast and etioplast, and isolating the high molecular weightcpRNA. After determining the contents, the high molecular weight cpRNA wasanalysed by Northern Blot hybridization with psbA gene. The results showed that theaccumulations of chlorophyll and high molecular weight cpRNA induced by differentlight quality were parallel each other. The inducing effects of different light qualitycan be ordered as follows: incandescent light > red light > blue light > far red light >dark control. In addition, the accumulations of cpRNA were more dependent to lightthan the accumulations of chlorophyll. The developed photosystems were fouhd inchloroplasts from the seedlings grown under incandescent light, blue light and red light.However, the undeveloped photosystems were found in the etioplast from the seedlingsunder far red light. According to the results of Northern Blot hybridization ofdigoxigenin-labelled psbA to cpRNA immobilized on nitrocellulose filter, theaccumulation of psbA transcripts induced by different light quality was similar to theaccumulations of chlorophyll and high molecular weight cpRNA. For this reason, wededuced that the transcription of psbA gene is constitutive in chloroplast and regulatedindirectly by light.
关键词
黍子
光质
叶绿体
发育
PSBA基因
基因转录
Broomcom millet (Panicum miliaceum)
Light quality
Chloloplast development
psbA gene
