Winder T L, Nishio J N
Department of Botany, University of Wyoming, Laramie 82071-3165, USA.
Plant Physiol. 1995 Aug;108(4):1487-94. doi: 10.1104/pp.108.4.1487.
Iron nutrient deficiency was investigated in leaves of hydroponically grown sugar beets (Beta vulgaris) to determine how ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) gene expression is affected when thylakoid components of photosynthesis are diminished. Rubisco polypeptide content was reduced by 60% in severely iron-stressed leaves, and the reduction was directly correlated to chlorophyll content. The concentration of Rubisco protein in iron-stressed leaves was found to be regulated by availability of mRNAs, and CO2 fixation by Rubisco was reduced from 45 mumol CO2 m-2 s-1 in extracts from iron-sufficient leaves to 20 mumol CO2 m-2 s-1 in extracts from severely stressed leaves. The rate of CO2 fixation was directly correlated to leaf chlorophyll content. Rubisco in iron-sufficient control leaves was 59% activated, whereas in severely stressed leaves grown under the same light, Rubisco was 43% activated. RNA synthesis was reduced by about 50% in iron-deficient leaves, but 16S and 25S rRNA and ctDNA were essentially unaffected by iron stress.
对水培甜菜（Beta vulgaris）叶片中的铁营养缺乏情况进行了研究，以确定当光合作用的类囊体成分减少时，1,5-二磷酸核酮糖羧化酶/加氧酶（Rubisco）基因表达是如何受到影响的。在铁严重缺乏的叶片中，Rubisco多肽含量降低了60%，且这种降低与叶绿素含量直接相关。研究发现，铁缺乏叶片中Rubisco蛋白的浓度受mRNA可用性的调节，Rubisco的二氧化碳固定能力从铁充足叶片提取物中的45 μmol CO₂ m⁻² s⁻¹降低到严重缺铁叶片提取物中的20 μmol CO₂ m⁻² s⁻¹。二氧化碳固定速率与叶片叶绿素含量直接相关。铁充足的对照叶片中的Rubisco有59%被激活，而在相同光照条件下生长的严重缺铁叶片中，Rubisco的激活率为43%。缺铁叶片中的RNA合成减少了约50%，但16S和25S rRNA以及叶绿体DNA基本不受铁胁迫的影响。
