The photosensitive phs1 mutant is impaired in the riboflavin biogenesis pathway.
A photosensitive (phs1) mutant of Arabidopsis thaliana was isolated and characterized. The PHS1 gene was cloned using a map-based approach. The gene was found to encode a protein containing a deaminase-reductase domain that is involved in the riboflavin pathway. The phenotype and growth of the phs1 mutant were comparable to that of the wild-type when the plants were grown under low light conditions. When the light intensity was increased, the mutant was characterized by stunted growth and bleached leaves as well as a decrease in FNR activity. The NADPH levels declined, whereas the NADP(+) levels increased, leading to a decrease in the NADPH/NADP(+) ratio. The mutant suffered from severe photooxidative damage with an increase in antioxidant enzyme activity and a drastic reduction in the levels of chlorophyll and photosynthetic proteins. Supplementing the mutant with exogenous FAD rescued the photosensitive phenotype, even under increasing light intensity. The riboflavin pathway therefore plays an important role in protecting plants from photooxidative damage.
Ouyang
Min
M
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
Ma
Jinfang
J
Zou
Meijuan
M
Guo
Jinkui
J
Wang
Liyuan
L
Lu
Congming
C
Zhang
Lixin
L
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000528:radiation effects / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000528:radiation effects; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000528:radiation effects / Q000648:ultrastructure; D003001:Cloning, Molecular; D005287:Ferredoxin-NADP Reductase / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D017343:Genes, Plant / Q000235:genetics; D015151:Immunoblotting; D007700:Kinetics; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction / Q000528:radiation effects; D018384:Oxidative Stress / Q000528:radiation effects; D010788:Photosynthesis / Q000528:radiation effects; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012256:Riboflavin / Q000096:biosynthesis*
D029681:Arabidopsis Proteins; D002734:Chlorophyll; D005182:Flavin-Adenine Dinucleotide; D009249:NADP; C001785:chlorophyll P 700; D005287:Ferredoxin-NADP Reductase; C514675:PHS1 protein, Arabidopsis; D017027:Protein Tyrosine Phosphatases; D012256:Riboflavin