Fig. 6

OsPIL11 facilitates the greening of etiolated seedlings. (a) Phenotypes of WT and ygl3 plants after light irradiation for 12 h at 28 °C. Ten-day-old etiolated seedlings were exposed to light. (b) Chlorophyll synthesis rate of 10-day-old etiolated seedlings (WT and ygl3) after light irradiation for 24 h at 28 °C. (c) Phenotypes of SN265 and OE-OsPIL11 plants after light irradiation for 12 h at 28 °C. Ten-day-old etiolated seedlings were exposed to light. Scale bar = 2 cm. (d and e) Chloroplast ultrastructures in SN265 and OE-OsPIL11 plants. (f) Chlorophyll contents of the SN265 and OE-OsPIL11 plants. Etiolated seedlings were grown in the darkness for 10 d at 28 °C and then exposed to light for 24 h. (g) Relative expressions of YGL3 and OsPIL11 in SN265 and OE-OsPIL11 plants based on qRT-PCR analysis. RNA was extracted from seedlings grown in the darkness for 10 d at 28 °C. (h) Activity of 4-hydroxy-3-methylbut-2-enyl diphosphate reductase in SN265 and OE-OsPIL11 plants. (i) IPP contents in SN265 and OE-OsPIL11 plants. (j) Transcription levels of thylakoid membrane genes in SN265 and OE-OsPIL11 plants. (k) Transcription levels of chlorophyll synthesis genes in SN265 and OE-OsPIL11 plants. (l) Proposed model for the regulation of chlorophyll synthesis by YGL3. YGL3 encodes a 4-hydroxy-3-methylbut-2-enyl diphosphate reductase that catalyzes the transformation of HMBPP to IPP and DMAPP, which are the precursors of chlorophyll synthesis. OsPIL11 directly activates the expression of YGL3 by binding to its promoter, increasing the contents of IPP and DMAPP to synthesize more chlorophyll. G3P, glyceraldehyde 3-phosphate; HMBPP, 4-hydroxy-3-methylbut-2-enyl diphosphate; IPP, isopentenyl diphosphate; DMAPP, dimethylallyl diphosphate. Asterisks indicate statistical significance as determined by Student’s t-test (**P < 0.01; 0.01 < *P < 0.05)