Differences in leaf anatomy, photosynthesis, and photoprotective strategies in the yellow-green leaf mutant and wild type of Rosa beggeriana Schrenk

Although the underlying mechanisms of chlorophyll biosynthesis have been intensively deciphered in model plants, leaf color mutants have not yet been fully studied in woody species. In this study, leaf anatomy, diurnal changes in photosynthesis and photoprotection were investigated in the yellow-green leaf (ygl) mutant of Rosa beggeriana. Chloroplast ultrastructure, pigment biosynthesis, and photosynthesis were impaired and led to photoinhibition at noon in the ygl mutant. The negative changes in leaf anatomy increased the risk of excess light absorption in the mutant. Moreover, the ygl mutant preferred to consume the excited energy through photorespiration rather than via heat dissipation. Finally, antioxidant defenses failed to scavenge reactive oxygen species and led to severe lipid peroxidation in the mutant. The results suggested that inhibition of photosynthesis in the ygl mutant of R. beggeriana was associated with the altered photoprotective strategies that involved in leaf anatomy, photorespiration, thermal dissipation, and antioxidant system.