In the present study, we investigated the changes of photosynthesis, chlorophyll fluorescence and the content of carotenoid pigments in rice (Oryza sativa L.) seedling leaves and their responses to high light. The res...In the present study, we investigated the changes of photosynthesis, chlorophyll fluorescence and the content of carotenoid pigments in rice (Oryza sativa L.) seedling leaves and their responses to high light. The results showed that the rate of photosynthesis, the contents of individual and total carotenoids and the pool size of xanthophyll cycle decreased with age increasing of the leaf. When the leaves were exposed to high light for 2 h, the qN of mature leaf (5th leaf) increased more significantly than that of younger (6th leaf) and older leaves (3rd and 4th leaf). Comparing with the leaves before exposure to high light, the excitation pressure on PSⅡ (1- qP ) increased by 44%, 57%, 19% and 45% in the 3rd, 4th, 5th and 6th leaf under high light, respectively. The highest content of carotenoids and the greatest conversion of violaxanthin to zeaxanthin were found in the 5th leaf, and it was consistent with the 5th leaf exhibiting the strongest resistance to high light. Our results suggested that the ability of rice leaf to resist photoinhibition is related to the level of carotenoids and the ability of carotenoids biosynthesis.展开更多
Carotenoids play an important role in many physiological processes in plants and the phytoene desaturase gene （PDS3） encodes one of the important enzymes in the carotenoid biosynthesis pathway. Here we report the id...Carotenoids play an important role in many physiological processes in plants and the phytoene desaturase gene （PDS3） encodes one of the important enzymes in the carotenoid biosynthesis pathway. Here we report the identification and analysis of a T-DNA insertion mutant of PDS3 gene. Functional complementation confirmed that both the albino and dwarfphenotypes ofthepds3 mutant resulted from functional disruption of the PDS3 gene. Chloroplast development was arrested at the proplastid stage in thepds3 mutant. Further analysis showed that high level ofphytoene was accumulated in the pds3 mutant. Addition of exogenous GA3 could partially rescue the dwarf phenotype, suggesting that the dwarf phenotype ofthepds3 mutant might be due to GA deficiency. Microarray and RT-PCR analysis showed that disrupting PDS3 gene resulted in gene expression changes involved in at least 20 metabolic pathways, including the inhibition of many genes in carotenoid, chlorophyll, and GA biosynthesis pathways. Our data suggest that the accumulated phytoene in the pds3 mutant might play an important role in certain negative feedbacks to affect gene expression of diverse cellular pathways.展开更多
The purpose of the present study is to optimize the cultivation conditions for the productivities of chlorophyll and carotenoid of the microalga chlorellafusca in a flow bioreactor. The effects of CO2 concentration in...The purpose of the present study is to optimize the cultivation conditions for the productivities of chlorophyll and carotenoid of the microalga chlorellafusca in a flow bioreactor. The effects of CO2 concentration in aeration and light intensity as the culture condition were firstly examined. After the cultivation conditions as to CO2 concentration and light intensity were determined, the effects of the concentrations of KNO3, CH3COONa, NaC1 and MgSO4 in the culture medium on the chlorophyll biosynthesis and carotenoid accumulation ofC. fusca were examined. KNO3 and CH3COONa were used as the nitrogen and the organic carbon sources, respectively. They are very important nutrient sources to the microalgae. In fact, when the concentration of the nutrient sources was increased, the syntheses of chlorophyll and the carotenoid accumulation of the microalgae were promoted. Cfusca can take an organic carbon as the nutrient sources for its own growth, so the cell is activated compared to the case only in an inorganic nourishment sources. Mg2＋ is known as a raw material of chlorophyll and it can promote carotenoid accumulation. However, when it exists in excessive quantity, the microalgae receive a stress and it was difficult for microalgae to uptake such nutrient sources. In this study, it was found that there existed the optimum amounts of KNO3, CH3COONa, NaCI and MgSO4 which should be added to the culture medium.展开更多
文摘In the present study, we investigated the changes of photosynthesis, chlorophyll fluorescence and the content of carotenoid pigments in rice (Oryza sativa L.) seedling leaves and their responses to high light. The results showed that the rate of photosynthesis, the contents of individual and total carotenoids and the pool size of xanthophyll cycle decreased with age increasing of the leaf. When the leaves were exposed to high light for 2 h, the qN of mature leaf (5th leaf) increased more significantly than that of younger (6th leaf) and older leaves (3rd and 4th leaf). Comparing with the leaves before exposure to high light, the excitation pressure on PSⅡ (1- qP ) increased by 44%, 57%, 19% and 45% in the 3rd, 4th, 5th and 6th leaf under high light, respectively. The highest content of carotenoids and the greatest conversion of violaxanthin to zeaxanthin were found in the 5th leaf, and it was consistent with the 5th leaf exhibiting the strongest resistance to high light. Our results suggested that the ability of rice leaf to resist photoinhibition is related to the level of carotenoids and the ability of carotenoids biosynthesis.
基金the National Natural Science Foundation of China （Grant No. 30470172）.
文摘Carotenoids play an important role in many physiological processes in plants and the phytoene desaturase gene （PDS3） encodes one of the important enzymes in the carotenoid biosynthesis pathway. Here we report the identification and analysis of a T-DNA insertion mutant of PDS3 gene. Functional complementation confirmed that both the albino and dwarfphenotypes ofthepds3 mutant resulted from functional disruption of the PDS3 gene. Chloroplast development was arrested at the proplastid stage in thepds3 mutant. Further analysis showed that high level ofphytoene was accumulated in the pds3 mutant. Addition of exogenous GA3 could partially rescue the dwarf phenotype, suggesting that the dwarf phenotype ofthepds3 mutant might be due to GA deficiency. Microarray and RT-PCR analysis showed that disrupting PDS3 gene resulted in gene expression changes involved in at least 20 metabolic pathways, including the inhibition of many genes in carotenoid, chlorophyll, and GA biosynthesis pathways. Our data suggest that the accumulated phytoene in the pds3 mutant might play an important role in certain negative feedbacks to affect gene expression of diverse cellular pathways.
文摘The purpose of the present study is to optimize the cultivation conditions for the productivities of chlorophyll and carotenoid of the microalga chlorellafusca in a flow bioreactor. The effects of CO2 concentration in aeration and light intensity as the culture condition were firstly examined. After the cultivation conditions as to CO2 concentration and light intensity were determined, the effects of the concentrations of KNO3, CH3COONa, NaC1 and MgSO4 in the culture medium on the chlorophyll biosynthesis and carotenoid accumulation ofC. fusca were examined. KNO3 and CH3COONa were used as the nitrogen and the organic carbon sources, respectively. They are very important nutrient sources to the microalgae. In fact, when the concentration of the nutrient sources was increased, the syntheses of chlorophyll and the carotenoid accumulation of the microalgae were promoted. Cfusca can take an organic carbon as the nutrient sources for its own growth, so the cell is activated compared to the case only in an inorganic nourishment sources. Mg2＋ is known as a raw material of chlorophyll and it can promote carotenoid accumulation. However, when it exists in excessive quantity, the microalgae receive a stress and it was difficult for microalgae to uptake such nutrient sources. In this study, it was found that there existed the optimum amounts of KNO3, CH3COONa, NaCI and MgSO4 which should be added to the culture medium.
