Chalkiness is one of the key factors determining rice quality and price. Ascorbic acid(Asc) is a major plant antioxidant that performs many functions in plants. L-Galactono-1,4-lactone dehydrogenase(L-Gal LDH, EC1.3.2...Chalkiness is one of the key factors determining rice quality and price. Ascorbic acid(Asc) is a major plant antioxidant that performs many functions in plants. L-Galactono-1,4-lactone dehydrogenase(L-Gal LDH, EC1.3.2.3) is an enzyme that catalyzes the final step of Asc biosynthesis in plants. Here we show that the L-Gal LDH-overexpressing transgenic rice, GO-2,which has constitutively higher leaf Asc content than wild-type(WT) plants, exhibits significantly reduced grain chalkiness. Higher foliar ascorbate/dehydroascorbate(Asc/DHA)ratios at 40, 60, 80, and 100 days of plant age were observed in GO-2. Further investigation showed that the enhanced level of Asc resulted in a significantly higher ribulose-1,5-bisphosphate(Ru BP) carboxylase/oxygenase(Rubisco) protein level in GO-2 at 80 days. In addition, levels of abscisic acid(ABA) and jasmonic acid(JA) were lower in GO-2 at 60, 80, and100 days. The results we present here indicate that the enhanced level of Asc is likely responsible for changing redox homeostasis in key developmental stages associated with grain filling and alters grain chalkiness in the L-Gal LDH-overexpressing transgenic by maintaining photosynthetic function and affecting phytohormones associated with grain filling.展开更多
The chemical composition, mineral elements, vitamins, free fatty acids and amino acid content of the edible red alga Gracilaria lemaneiformis Bory, grown in the sea near Nan'ao island, Guangdong Province, were analyz...The chemical composition, mineral elements, vitamins, free fatty acids and amino acid content of the edible red alga Gracilaria lemaneiformis Bory, grown in the sea near Nan'ao island, Guangdong Province, were analyzed in the present study. Gracilaria lemaneiformis Bory showed a total sugar content of 14.65%. The protein content was 21%, of which approximately 41% was determined to be essential amino acids (EAA). The major amino acid components were glutamic acid, leucine, arginine, and alanine. Of the EAA assayed, methionine and cysteine appeared to be the most limiting amino acids compared with the EAA pattern provided by Food and Agricultural Organization of the United Nations. The total lipids content was 0.87% and comprised a high composition of unsaturated fatty acids (61%), mainly as linoleic acid and oleic acid, and a little amount of polyunsaturated fatty acid; palmitic acid was the main component (39%) of saturated acids. Relatively high levels of vitamin C, iodine, phosphorus, and zinc were also present in G. lemaneiformis. The nutritional composition between G. lemaneiformis and Nostoc flagelliforme, a rare alga that is widely eaten in Chinese society, was compared. The results suggest that N. flagelliforme can be substituted for by G. lemaneiformis, not only because of their similar shape, but also because of their approximate nutritional composition. Gracilaria lemaneiformis may possibly serve as a potential healthy food in human diets in the future.展开更多
Aims Natural hybridization between invasive and native species,as a form of adaptive evolution,threatens biodiversity worldwide.However,the potential invasive mechanisms of hybrids remain essentially unexplored,especi...Aims Natural hybridization between invasive and native species,as a form of adaptive evolution,threatens biodiversity worldwide.However,the potential invasive mechanisms of hybrids remain essentially unexplored,especially insights from soil chemical properties and soil microbial communities.Methods In a field experiment,soil microbial community,potassium-solubilizing bacteria,phosphorus-solubilizing bacteria,enzyme activities,and light-saturated photosynthetic rate were measured in invasive Sphagneticola trilobata and its hybrid with native Sphagneticola calendulacea in 2 years.Important Findings In general,soil dissolved organic carbon and the biomass of phosphorus-solubilizing bacteria were significantly higher under the hybrid treatment than S.trilobata and S.calendulacea.However,there were no significant differences in acid phosphatase,total PLFAs,bacterial PLFAs,fungi PLFAs,cellulase,and urase in these treatments.The hybrids had significantly higher light-saturated photosynthetic rate,photosynthetic nitrogen-,phosphorus-,potassium-use efficiencies than the invasive S.trilobata,but no significant difference with S.calendulacea.The total biomass and root biomass of hybrids were higher than S.calendulacea.Our results indicate that the hybrids species have a higher invasive potential than S.calendulacea,which may aggravate the local extinction of S.calendulacea in the future.展开更多
Calcium is important for chloroplast, not only in its photosynthetic but also nonphotosynthetic functions. Mul- tiple Ca2+/H+ transporters and channels have been described and studied in the plasma membrane and orga...Calcium is important for chloroplast, not only in its photosynthetic but also nonphotosynthetic functions. Mul- tiple Ca2+/H+ transporters and channels have been described and studied in the plasma membrane and organ- elle membranes of plant cells; however, the molecular identity and physiological roles of chloroplast Ca2+/H+ antiporters have remained unknown. Here we report the identification and characterization of a member of the UPFO016 family, CCHA1 (a chloroplast-localized potential Ca2+/H+ antiporter), in Arabidopsis thaliana. We observed that the ccha I mutant plants developed pale green leaves and showed severely stunted growth along with impaired photosystem II (PSII) function. CCHA1 localizes to the chloroplasts, and the levels of the PSII core subunits and the oxygen-evolving complex were significantly decreased in the ccha I mutants compared with the wild type. In high Ca2+ concentrations, Arabidopsis CCHA1 partially rescued the growth defect of yeast gdtl3 null mutant, which is defective in a Ca2+/H+ antiporter. The cchal mutant plants also showed significant sensitivity to high concentrations of CaCI2 and MnCI2, as well as variation in pH. Taken these results together, we propose that CCHA 1 might encode a putative chloroplast-localized Ca2+/H+ antiporter with critical functions in the regulation of PSII and in chloroplast Ca2+ and pH homeostasis in Arabidopsis.展开更多
Type III antifreeze proteins(AFPIIIs)are a group of small globular proteins found in some polar fishes to protect them against freezing damage.Transgenic expression of AFPs has been shown to confer cold tolerance to c...Type III antifreeze proteins(AFPIIIs)are a group of small globular proteins found in some polar fishes to protect them against freezing damage.Transgenic expression of AFPs has been shown to confer cold tolerance to commercially important plants and animals.We have previously isolated multiple AFPIII genes in the Antarctic eelpout(Lycodichthys dearborni)that encode larger AFPIII isoforms with up to 12 of the conventional domains.Here we have introduced the fish AFPIII genes that encode for the monomer(ld1),dimer(ld2),trimer(ld3)and tetramer(ld4)AFPIII isoforms in tobacco plants.Pot-grown 4-week-old transgenic tobacco plants were exposed to cold stress at 4◦C for 30 days and the results show that ld1,ld2,ld3 and ld4 transgenic plants present relatively lower electrolyte leakage and lower content of malondialdehyde(MDA),but accumulated higher content of proline when compared to control plants.This indicates considerable improved membrane integrity under low temperature stress and improvement of the plant cold resistance.The plants transformed with the AFPIII tetramer-and trimer-domains demonstrated a higher cold-tolerant levels when compared with plants transformed with the dimer-and monomer AFPIII domains.Our study further supports that fish AFPIIIs,especially the multidomain proteins,protect cells from non-freezing hypothermic stresses,apart from there well-known function as ice inhibitors molecules at freezing temperature.展开更多
Aims Anthocyanin accumulation is the main factor underlying why young plant leaves turn red,and plant growth follows the principle of maximizing the economic efficiency of energy.There is a need to verify the role of ...Aims Anthocyanin accumulation is the main factor underlying why young plant leaves turn red,and plant growth follows the principle of maximizing the economic efficiency of energy.There is a need to verify the role of young plant leaves turning red and confirm whether anthocyanin accumulation overconsumes the energy of the plant.Methods We compared the different pigment contents,antioxidant capaci-ties,leaf mass per area,photosynthetic characteristics,dark res-piration rates,light compensation points(LCPs)and electron flow distribution of young and mature Schima superba leaves grown under full sunlight and 30%full sunlight conditions.We then exam-ined the correlations between anthocyanins and total antioxidant capacity,photosynthetic pigments,dark respiration rates,LCPs by using linear regression.Finally,we analyzed Pearson correlation coefficients and used principal component analysis to evaluate the interactions of these functional indicators.Important Findings The young leaves of S.superba accumulated anthocyanins in full sunlight but not in 30%full sunlight.Anthocyanins substantially con-tributed to the total antioxidant capacity(accounting for 33.29%)in juvenile S.superba leaves.Young leaves containing more anthocyanin accumulated less reactive oxygen species after high light(HL)treat-ment.However,juvenile leaves accumulating anthocyanins showed 56.97%higher dark respiration rates,24.79%higher LCPs and 5.32%higher allocations of electron flow to photorespiration and lower organic substance accumulation than did those without anthocyanins.These results suggest that young S.superba leaves must consume more energy to accumulate anthocyanins to adapt to HL environments.Therefore,plants sacrifice growth rate to ensure survival,which is a trade-off for their ability to respond to external environments.展开更多
基金supported by the National Natural Science Foundation of China (31270287, 31301244, 31471432)the Natural Science Foundation of Guangdong Province, China (2014A030313663, S2012010010680)
文摘Chalkiness is one of the key factors determining rice quality and price. Ascorbic acid(Asc) is a major plant antioxidant that performs many functions in plants. L-Galactono-1,4-lactone dehydrogenase(L-Gal LDH, EC1.3.2.3) is an enzyme that catalyzes the final step of Asc biosynthesis in plants. Here we show that the L-Gal LDH-overexpressing transgenic rice, GO-2,which has constitutively higher leaf Asc content than wild-type(WT) plants, exhibits significantly reduced grain chalkiness. Higher foliar ascorbate/dehydroascorbate(Asc/DHA)ratios at 40, 60, 80, and 100 days of plant age were observed in GO-2. Further investigation showed that the enhanced level of Asc resulted in a significantly higher ribulose-1,5-bisphosphate(Ru BP) carboxylase/oxygenase(Rubisco) protein level in GO-2 at 80 days. In addition, levels of abscisic acid(ABA) and jasmonic acid(JA) were lower in GO-2 at 60, 80, and100 days. The results we present here indicate that the enhanced level of Asc is likely responsible for changing redox homeostasis in key developmental stages associated with grain filling and alters grain chalkiness in the L-Gal LDH-overexpressing transgenic by maintaining photosynthetic function and affecting phytohormones associated with grain filling.
文摘The chemical composition, mineral elements, vitamins, free fatty acids and amino acid content of the edible red alga Gracilaria lemaneiformis Bory, grown in the sea near Nan'ao island, Guangdong Province, were analyzed in the present study. Gracilaria lemaneiformis Bory showed a total sugar content of 14.65%. The protein content was 21%, of which approximately 41% was determined to be essential amino acids (EAA). The major amino acid components were glutamic acid, leucine, arginine, and alanine. Of the EAA assayed, methionine and cysteine appeared to be the most limiting amino acids compared with the EAA pattern provided by Food and Agricultural Organization of the United Nations. The total lipids content was 0.87% and comprised a high composition of unsaturated fatty acids (61%), mainly as linoleic acid and oleic acid, and a little amount of polyunsaturated fatty acid; palmitic acid was the main component (39%) of saturated acids. Relatively high levels of vitamin C, iodine, phosphorus, and zinc were also present in G. lemaneiformis. The nutritional composition between G. lemaneiformis and Nostoc flagelliforme, a rare alga that is widely eaten in Chinese society, was compared. The results suggest that N. flagelliforme can be substituted for by G. lemaneiformis, not only because of their similar shape, but also because of their approximate nutritional composition. Gracilaria lemaneiformis may possibly serve as a potential healthy food in human diets in the future.
基金funded by the National Natural Science Foundation of China(41907023,31870374)the China Postdoctoral Science Foundation(2018M643112)and the China Postdoctoral Science Foundation(2018M643112)+1 种基金the State Key Laboratory for Biology of Plant Diseases and Insect Pests(SKLOF201914)supported by Guangdong Province Natural Science Foundation(2017A030313167,2015A030311023).
文摘Aims Natural hybridization between invasive and native species,as a form of adaptive evolution,threatens biodiversity worldwide.However,the potential invasive mechanisms of hybrids remain essentially unexplored,especially insights from soil chemical properties and soil microbial communities.Methods In a field experiment,soil microbial community,potassium-solubilizing bacteria,phosphorus-solubilizing bacteria,enzyme activities,and light-saturated photosynthetic rate were measured in invasive Sphagneticola trilobata and its hybrid with native Sphagneticola calendulacea in 2 years.Important Findings In general,soil dissolved organic carbon and the biomass of phosphorus-solubilizing bacteria were significantly higher under the hybrid treatment than S.trilobata and S.calendulacea.However,there were no significant differences in acid phosphatase,total PLFAs,bacterial PLFAs,fungi PLFAs,cellulase,and urase in these treatments.The hybrids had significantly higher light-saturated photosynthetic rate,photosynthetic nitrogen-,phosphorus-,potassium-use efficiencies than the invasive S.trilobata,but no significant difference with S.calendulacea.The total biomass and root biomass of hybrids were higher than S.calendulacea.Our results indicate that the hybrids species have a higher invasive potential than S.calendulacea,which may aggravate the local extinction of S.calendulacea in the future.
文摘Calcium is important for chloroplast, not only in its photosynthetic but also nonphotosynthetic functions. Mul- tiple Ca2+/H+ transporters and channels have been described and studied in the plasma membrane and organ- elle membranes of plant cells; however, the molecular identity and physiological roles of chloroplast Ca2+/H+ antiporters have remained unknown. Here we report the identification and characterization of a member of the UPFO016 family, CCHA1 (a chloroplast-localized potential Ca2+/H+ antiporter), in Arabidopsis thaliana. We observed that the ccha I mutant plants developed pale green leaves and showed severely stunted growth along with impaired photosystem II (PSII) function. CCHA1 localizes to the chloroplasts, and the levels of the PSII core subunits and the oxygen-evolving complex were significantly decreased in the ccha I mutants compared with the wild type. In high Ca2+ concentrations, Arabidopsis CCHA1 partially rescued the growth defect of yeast gdtl3 null mutant, which is defective in a Ca2+/H+ antiporter. The cchal mutant plants also showed significant sensitivity to high concentrations of CaCI2 and MnCI2, as well as variation in pH. Taken these results together, we propose that CCHA 1 might encode a putative chloroplast-localized Ca2+/H+ antiporter with critical functions in the regulation of PSII and in chloroplast Ca2+ and pH homeostasis in Arabidopsis.
基金The work is supported by Natural Science Foundation of China[31572611]the National Key Research and Development Program of China[2018YFD0900601]the Major Science Innovation Grant[2017-01-07-00-10-E00060]from the Shanghai Education Committee to L.Chen.
文摘Type III antifreeze proteins(AFPIIIs)are a group of small globular proteins found in some polar fishes to protect them against freezing damage.Transgenic expression of AFPs has been shown to confer cold tolerance to commercially important plants and animals.We have previously isolated multiple AFPIII genes in the Antarctic eelpout(Lycodichthys dearborni)that encode larger AFPIII isoforms with up to 12 of the conventional domains.Here we have introduced the fish AFPIII genes that encode for the monomer(ld1),dimer(ld2),trimer(ld3)and tetramer(ld4)AFPIII isoforms in tobacco plants.Pot-grown 4-week-old transgenic tobacco plants were exposed to cold stress at 4◦C for 30 days and the results show that ld1,ld2,ld3 and ld4 transgenic plants present relatively lower electrolyte leakage and lower content of malondialdehyde(MDA),but accumulated higher content of proline when compared to control plants.This indicates considerable improved membrane integrity under low temperature stress and improvement of the plant cold resistance.The plants transformed with the AFPIII tetramer-and trimer-domains demonstrated a higher cold-tolerant levels when compared with plants transformed with the dimer-and monomer AFPIII domains.Our study further supports that fish AFPIIIs,especially the multidomain proteins,protect cells from non-freezing hypothermic stresses,apart from there well-known function as ice inhibitors molecules at freezing temperature.
基金This work was funded by the National Natural Science Foundation of China(31570398)The study was also sup-ported by Guangdong Province Natural Science Foundation(2017A030313167,2015A030311023).Conflict of interest statement.None declared.
文摘Aims Anthocyanin accumulation is the main factor underlying why young plant leaves turn red,and plant growth follows the principle of maximizing the economic efficiency of energy.There is a need to verify the role of young plant leaves turning red and confirm whether anthocyanin accumulation overconsumes the energy of the plant.Methods We compared the different pigment contents,antioxidant capaci-ties,leaf mass per area,photosynthetic characteristics,dark res-piration rates,light compensation points(LCPs)and electron flow distribution of young and mature Schima superba leaves grown under full sunlight and 30%full sunlight conditions.We then exam-ined the correlations between anthocyanins and total antioxidant capacity,photosynthetic pigments,dark respiration rates,LCPs by using linear regression.Finally,we analyzed Pearson correlation coefficients and used principal component analysis to evaluate the interactions of these functional indicators.Important Findings The young leaves of S.superba accumulated anthocyanins in full sunlight but not in 30%full sunlight.Anthocyanins substantially con-tributed to the total antioxidant capacity(accounting for 33.29%)in juvenile S.superba leaves.Young leaves containing more anthocyanin accumulated less reactive oxygen species after high light(HL)treat-ment.However,juvenile leaves accumulating anthocyanins showed 56.97%higher dark respiration rates,24.79%higher LCPs and 5.32%higher allocations of electron flow to photorespiration and lower organic substance accumulation than did those without anthocyanins.These results suggest that young S.superba leaves must consume more energy to accumulate anthocyanins to adapt to HL environments.Therefore,plants sacrifice growth rate to ensure survival,which is a trade-off for their ability to respond to external environments.