Positive Regulation of Phytochrome B on Chlorophyll Biosynthesis and Chloroplast Development in Rice

Phytochromes in rice are encoded by a gene family composed of three members, PHYA, PHYB, and PHYC. Through characterizing the phytochrome mutants and wild type （WT） in terms of photomorphogenesis, roles of individual phytochromes have been preliminarily explored in regulating rice de-etiolation, flowering time and fertility. However, little information has been reported about whether or how phytochromes affect chlorophyll biosynthesis and chloroplast development in rice. In this study, we compared the chlorophyll contents of wild type and the phyA, phyB and phyAphyB mutants grown under either white light （WL） or red light （R）. The results suggest that phyB perceives R to positively regulate chlorophyll biosynthesis, while the role of phyA can be detected only in the phyB-deficient mutant. Analyses of the expression levels of genes involved in chlorophyll biosynthesis revealed that phytochromes affected the chlorophyll biosynthesis by regulating protochlorophyll oxidoreductase A （PORA） expression. The role of phyB in chloroplast development was also analyzed, and the results suggest that phyB perceives R to regulate chloroplast development by affecting the numbers of chloroplasts and grana, as well as the chloroplast membrane system.

Pumpkin seed coat pigments affected aqueous enzymatic extraction processing through interaction with its interfacial protein

In this study,the oil recovery from pumpkin seed with or without the presence of pigment was evaluated during the aqueous enzymatic extraction process(AEEP).Additionally,the interaction of pumpkin seed coat pigment-protochlorophyll(Pchl)with interfacial proteins(globulin-O/W,globulin-W,and albumin-W)during the aqueous extraction process was investigated.When Pchl was removed from pumpkin seeds,the yield of free oil was significantly increased by 50.71%after the first centrifugation.And the total oil recovery increased from 68.59%to 89.91%using enzymatic demulsification.Theβ-sheet percentage of globulin-O/W decreased by 5.6%with the presence of Pchl based on the circular dichroism spectra analysis.The particle size of globulin-W and albumin-W significantly increased in contrast to globulin-O/W.In addition,the increase of surface hydrophobicity and surface sulfhydryl group showed a conformational change of three protein extracts.Fluorescence spectra analyses showed that Pchl quenched the intrinsic fluorescence of globulin-W,albumin-W,and globulin-O/W in a static mode.Thermodynamic analyses indicated that the main force between Pchl and proteins was hydrophobic interactions.The hydrolysis efficiency of Papain was reduced during demulsification in AEEP with the presence of Pchl.Therefore,the removal of pumpkin seed coat pigments facilitated the aqueous extraction of seed oil by getting rid of the interaction of Pchl with its interfacial protein.