Early iron deficiency stress response in leaves of sugar beet.
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.
Winder
T L
TL
Department of Botany, University of Wyoming, Laramie 82071-3165, USA.
Nishio
J N
JN
D001483:Base Sequence; D018742:DNA, Chloroplast / Q000032:analysis; D018506:Gene Expression Regulation, Plant; D000090463:Iron Deficiencies; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000502:physiology*; D010940:Plant Proteins / Q000096:biosynthesis*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D012335:RNA, Ribosomal / Q000032:analysis; D012273:Ribulose-Bisphosphate Carboxylase / Q000096:biosynthesis* / Q000235:genetics; D014158:Transcription, Genetic; D014675:Vegetables
D018742:DNA, Chloroplast; D010940:Plant Proteins; D012333:RNA, Messenger; D012335:RNA, Ribosomal; D012273:Ribulose-Bisphosphate Carboxylase