Here, we report that phytochrome B (phyB) mutants exhibit improved cold tolerance compared with wild type (WT) rice (Oryza sativa L. Thus, OsFLU1 is an important regulator of chlorophyll biosynthesis in rice.Ĭross talk between light signaling and cold signaling has been elucidated in the model plant Arabidopsis and tomato, but little is known about their relationship in rice. Dark-grown transgenic rice seedlings overexpressing OsPIL14 accumulated more chlorophyll and turned green faster than the wild type upon light illumination. Rice phytochrome-interacting factor-like14 (OsPIL14) transcription factor directly bound to the OsFLU1 promoter and activated its expression. Molecular and complementation studies revealed that oxp is a loss-of-function mutant in LOC_Os01g32730, a homolog of fluorescent (FLU) in Arabidopsis thaliana. Several singlet-oxygen-responsive genes were greatly upregulated in oxp, while the expression patterns of OsPORA and OsPORB, two genes encoding the chlorophyll biosynthesis enzyme NADPH:protochlorophyllide oxidoreductase, were altered in de-etiolated oxp seedlings. The oxp mutant accumulated more chlorophyll precusors (5-aminolevulinic acid and protochlorophyllide) than the wild type in the dark, and more singlet oxygen following light exposure. In this study, we identified a rice (Oryza sativa) mutant, oxidation under photoperiod (oxp), that displayed photobleached lesions on its leaves, reduced growth, and decreased chlorophyll content during light/dark cycles or following a dark-to-light transition. The accumulation of excess chlorophyll biosynthesis intermediates under light results in the production of reactive oxygen species and oxidative stress. Considered together, our data indicate that OsPIL11 and OsPIL16 primarily function as transcriptional activators, at least in regards to promoting skotomorphogenesis and repressing the expression of photosynthesis-related genes.Ĭhlorophyll biosynthesis plays essential roles in photosynthesis and plant growth in response to environmental conditions. In contrast, the expression levels of these photosynthesis-related genes were down-regulated in dark-grown transgenic seedlings overexpressing OsPIL11 or OsPIL16, which had exaggerated skotomorphogenesis. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses indicated that the expression levels of genes related to photosynthesis, photosynthesis–antenna proteins, and porphyrin and chlorophyll metabolism were up-regulated in the dark-grown OsPIL11 - SRDX and OsPIL16 - SRDX lines, whereas the expression of genes related to the auxin pathway was down-regulated. The results of an RNA sequencing analysis revealed that the dark-grown OsPIL11 - SRDX and OsPIL16 - SRDX lines had gene expression patterns similar to those of wild-type seedlings grown under red light. The OsPIL11 - SRDX and OsPIL16 - SRDX seedlings grown in darkness had constitutively photomorphogenic phenotypes with short coleoptiles and open leaf blades. In the present study, to explore the functions of PILs in rice skotomorphogenesis, we generated OsPIL11 - SRDX and OsPIL16 - SRDX transgenic lines by fusing the SRDX transcriptional repressor motif to the C-terminal of two members of the phytochrome interacting factor-like (OsPIL) family in rice (OsPIL11 and OsPIL16).
#SRDX ANALYSIS ACTIVATOR#
It has been reported that SRDX motif, LDLDLELRLGFA, was able to convert a transcriptional activator into a strong repressor. Because of the development of rice direct seeding cultivation systems, there is an increasing need for clarifying the molecular mechanism underlying rice skotomorphogenic development. Dark-grown seedlings develop skotomorphogenically.