Crop yield depends on biomass,which is primarily associated with photosynthesis.We previously demonstrated that two photorespiratory bypasses,i.e.,GOC(glycolate oxidase+oxalate oxidase+catalase)and GCGT(glycolate oxid...Crop yield depends on biomass,which is primarily associated with photosynthesis.We previously demonstrated that two photorespiratory bypasses,i.e.,GOC(glycolate oxidase+oxalate oxidase+catalase)and GCGT(glycolate oxidase+catalase+glyoxylate carboligase+tartronic semialdehyde reductase),significantly increased photosynthesis,biomass,and grain yield,but decreased seed-setting rates in rice.This study explored the underlying mechanism of how elevated photosynthetic efficiency impacted the seed-setting.First,pollen germination assessed in vivo and in vitro,revealed a reduced germination rate in GCGT rice.Subsequent analysis found that photosynthates highly accumulated in the leaves and stems;sucrose and soluble sugar levels were increased but the starch level was reduced in the anthers.Uridine diphosphate glucose(UDP-Glc)was increased but uridine diphosphate galactose(UDP-Gal)was unaltered,thus causing an imbalance in the UDP-Glc/UDP-Gal ratio in GCGT anthers.Most anthers in GCGT plants had two locules in contrast to four in the wild-type(WT).Pollen tapetum was developmentally abnormal,and genes related to sucrose synthesis,transport,and tapetal programmed cell death(PCD)were upregulated,whereas those involved in starch synthesis and conversion were downregulated in GCGT anthers.Taken together,our results demonstrated that an increase in sugar content was the primary factor causing reduced seed-setting rates in high photosynthetic efficiency rice,during which metabolic disorder of sugars and UDP sugar imbalance in anthers lead to impaired pollen fertility.展开更多
The transport of proteins to and from the nucleus is necessary for many cellular processes and is one of the ways plants respond to developmental signals and environmental stresses.Nucleocytoplasmic trafficking of pro...The transport of proteins to and from the nucleus is necessary for many cellular processes and is one of the ways plants respond to developmental signals and environmental stresses.Nucleocytoplasmic trafficking of proteins is mediated by the nuclear transport receptor(NTR).Although NTR has been extensively studied in humans and Arabidopsis,it has rarely been identified and functionally characterized in rice.In this study,we identified exportin 1 in rice(OsXPO1)as a nuclear export receptor.OsXPO1shares high protein identity with its functional homologs in Arabidopsis and other organisms.OsXPO1localized to both the nucleus and the cytoplasm,directly interacted with the small GTPases OsRAN1and OsRAN2 in the nucleus,and mediated their nuclear export.Loss-of-function osxpo1 mutations were lethal at the seedling stage.Suppression of OsXPO1 expression in RNA interference lines produced multifaceted developmental defects,including arrested growth,premature senescence,abnormal inflorescence,and brown and mouth-opened spikelets.Overexpression of OsXPO1 in rice reduced plant height and seed-setting rate,but increased plant tolerance in response to PEG-mimicked drought stress and salt stress.These results indicate that OsXPO1 is a nuclear export receptor and acts in regulating plant development and abiotic stress responses.展开更多
In C_(3) plants,photorespiration is an energy expensive pathway that competes with photosynthetic CO_(2) assimilation and releases CO_(2) into the atmosphere,potentially reducing C_(3) plant productivity by 20%-50%.Co...In C_(3) plants,photorespiration is an energy expensive pathway that competes with photosynthetic CO_(2) assimilation and releases CO_(2) into the atmosphere,potentially reducing C_(3) plant productivity by 20%-50%.Consequently,reducing the flux through photorespiration has been recognized as a major way to improve C_(3) crop photosynthetic carbon fixation and productivity.While current research efforts in engineering photorespiration are mainly based on the modification of chloroplast glycolate metabolic steps,only limited studies have explored optimizations in other photorespiratory metabolic steps.Here,we engineered an imGS bypass within the rice mitochondria to bypass the photorespiratory glycine toward glycine betaine,thereby,improving the photosynthetic carbon fixation in rice.The imGS transgenic rice plants exhibited significant accumulation of glycine betaine,reduced photorespiration,and elevated photosynthesis and photosynthate levels.Additionally,the introduction of imGS bypass into rice leads to an increase in the number of branches and grains per panicle which may be related to cytokinin and gibberellin signaling pathways.Taken together,these results suggest diverting mitochondrial glycine from photorespiration toward glycine betaine synthesis can effectively enhance carbon fixation and panicle architecture in rice,offering a promising strategy for developing functional mitochondrial photorespiratory bypasses with the potential to enhance plant productivity.展开更多
Huanglongbing(HLB)is a devastating disease that has led to an acute crisis for growers of citrus,one of the world's most important fruit crops.The phloem-feeding Asian citrus psyllid(ACP),Diaphorina citri,is the m...Huanglongbing(HLB)is a devastating disease that has led to an acute crisis for growers of citrus,one of the world's most important fruit crops.The phloem-feeding Asian citrus psyllid(ACP),Diaphorina citri,is the main pest at the new shoot stage and is the only natural vector of HLB pathogenic bacteria.Little is known about how plants perceive and defend themselves from this destructive pest.Here,we characterized changes in the expression of various genes in citrus plants that were continuously infested by D.citri for different durations(12,24,and 48 h).A total of 5219 differentially expressed genes(DEGs)and 643 common DEGs were identified across all time points.Several pathways related to defense were activated,such as peroxisome,alpha-linolenic acid metabolism,and phenylpropanoid and terpenoid biosynthesis,and some pathways related to growth and signal transduction were suppressed in response to D.citri infestation.The expression of genes including kinases(CML44,CIPK6,and XTH6),phytohormones(SAMT,LOX6,and NPR3),transcription factors(bHLH162,WRKY70,and WRKY40),and secondary metabolite synthesis-related genes(PAL,4CL2,UGT74B1 and CYP82G1)was significantly altered in response to D.citri infestation.The findings of this study greatly enhance our understanding of the mechanisms underlying the defense response of citrus plants to D.citri infestation at the molecular level.Functional characterization of the candidate defense-related genes identified in this study will aid the molecular breeding of insect-resistant citrus varieties.展开更多
WD40 repeat-containing proteins(WD40 proteins)serve as versatile scaffolds for protein-protein interac-tions,modulating a variety of cellular processes such as plant stress and hormone responses.Here we report the ide...WD40 repeat-containing proteins(WD40 proteins)serve as versatile scaffolds for protein-protein interac-tions,modulating a variety of cellular processes such as plant stress and hormone responses.Here we report the identification of a WD40 protein,XIW1(for XPO1-interacting WD40 protein 1),which positively regulates the abscisic acid(ABA)response in Arabidopsis.XIW1 is located in the cytoplasm and nucleus.We found that it interacts with the nuclear transport receptor XPO1 and is exported by XPO1 from the nucleus.Mutation of XIW1 reduces the induction of ABA-responsive genes and the accumulation of ABA Insensitive 5(ABI5),causing mutant plants with ABA-insensitive phenotypes during seed germination and seedling growth,and decreased drought stress resistance.ABA treatment upregulates the expression of XIW1,and both ABA and abiotic stresses promote XIW1 accumulation in the nucleus,where it interacts with ABI5.Loss of XIW1 function results in rapid proteasomal degradation of ABI5.Taken together,these findings suggest that XIW1 is a nucleocytoplasmic shuttling protein and plays a positive role in ABA responses by interacting with and maintaining the stability of ABI5 in the nucleus.展开更多
Mutations in the photorespiration pathway dis- play a lethal phenotype in atmospheric air, which can be fully recovered by elevated C02. An exception is that mutants of peroxisomal hydroxypyruvate reductase （HPR1） d...Mutations in the photorespiration pathway dis- play a lethal phenotype in atmospheric air, which can be fully recovered by elevated C02. An exception is that mutants of peroxisomal hydroxypyruvate reductase （HPR1） do not have this phenotype, indicating the presence of cytosolic bypass in the photorespiration pathway. In this study, we constructed overexpression of the OsHPR1 gene and RNA interference plants of OsHPR1 and OsHPR2 genes in rice （Oryza sativo L. cv. Zhonghua 11）. Results from reverse transcription-polymerase chain reaction （RT-PCR）, Western blot, and enzyme assays showed that HPR1 activity changed significantly in corresponding transgenic lines without any effect on HPR2 activity, which is the same for HPR2. However, metabolite analysis and the serine glyoxylate aminotransferase （SGAT） activity assay showed that the metabolite flux of photorespiration was disturbed in RNAi lines of both HPR genes. Furthermore, HPR1 and HPR2 proteins were located to the peroxisome and cytosol, respectively, by transient expression experiment. Double mutant hprl x hpr2 was generated by crossing individual mutant of hprl and hpr2. The phenotypes of all transgenic lines were determined in ambient air and C02-elevated air. The phenotype typical of photorespiration mutants was observed only where activity of both HPRI and HPR2 were downregulated in the same line. These findings demonstrate that two hydroxypyruvate reductases encoded by OsHPRI and OsHPR2 are involved in photorespiratory metabolism in rice.展开更多
Based on the evidence that Al resistance is an inducible process and rice is an Al-resistant crop, identification of Al-responsive genes from rice may help to further clone Al.resistant genes in plants. Semi-quantitat...Based on the evidence that Al resistance is an inducible process and rice is an Al-resistant crop, identification of Al-responsive genes from rice may help to further clone Al.resistant genes in plants. Semi-quantitative and real-time polymerase chain reaction （PCR） is widely applied in gene transcrip- tional analyses, particularly for those genes with low transcript abundance. Normalization with proper endogenous control （EC） genes is critical for these two approaches in terms of reliability and precision. We first noticed that the expression of several commonly-used EC genes was depressed under AI stress, while sulfite reductase gene （SR） was stable throughout the AI treatment. The reliability of SR as an EC gene was further tested by analyzing the expression of a number of genes in response to Al challenge. Except for the consistent results obtained for the four previously-identified genes, nine additional genes were newly defined as Al-responsive in this study. Collectively, our results suggest that SR can be used as a novel EC gene for semi-quantitative and real-time PCR analysis of Al responsive genes, and that activated transport of silicon and stimulated metabolism of carotenoid and terpenoid could be involved in Al resistance in rice plants.展开更多
基金supported by the National Key Research and Development Program of China (2020YFA0907600)the Major Program of Guangdong Basic and Applied Research (2019B030302006)+1 种基金the National Natural Science Foundation of China (32101647)the Double First-Class Discipline Promotion Project (2023B10564004).
文摘Crop yield depends on biomass,which is primarily associated with photosynthesis.We previously demonstrated that two photorespiratory bypasses,i.e.,GOC(glycolate oxidase+oxalate oxidase+catalase)and GCGT(glycolate oxidase+catalase+glyoxylate carboligase+tartronic semialdehyde reductase),significantly increased photosynthesis,biomass,and grain yield,but decreased seed-setting rates in rice.This study explored the underlying mechanism of how elevated photosynthetic efficiency impacted the seed-setting.First,pollen germination assessed in vivo and in vitro,revealed a reduced germination rate in GCGT rice.Subsequent analysis found that photosynthates highly accumulated in the leaves and stems;sucrose and soluble sugar levels were increased but the starch level was reduced in the anthers.Uridine diphosphate glucose(UDP-Glc)was increased but uridine diphosphate galactose(UDP-Gal)was unaltered,thus causing an imbalance in the UDP-Glc/UDP-Gal ratio in GCGT anthers.Most anthers in GCGT plants had two locules in contrast to four in the wild-type(WT).Pollen tapetum was developmentally abnormal,and genes related to sucrose synthesis,transport,and tapetal programmed cell death(PCD)were upregulated,whereas those involved in starch synthesis and conversion were downregulated in GCGT anthers.Taken together,our results demonstrated that an increase in sugar content was the primary factor causing reduced seed-setting rates in high photosynthetic efficiency rice,during which metabolic disorder of sugars and UDP sugar imbalance in anthers lead to impaired pollen fertility.
基金supported by the National Key Research and Development Program(2020YFA0907600)the Laboratory of Lingnan Modern Agriculture Project(NZ2021004)+1 种基金the Natural Science Foundation of Guangdong Province(2020A1515010157)the Science and Technology Program of Guangzhou(202102080499)。
文摘The transport of proteins to and from the nucleus is necessary for many cellular processes and is one of the ways plants respond to developmental signals and environmental stresses.Nucleocytoplasmic trafficking of proteins is mediated by the nuclear transport receptor(NTR).Although NTR has been extensively studied in humans and Arabidopsis,it has rarely been identified and functionally characterized in rice.In this study,we identified exportin 1 in rice(OsXPO1)as a nuclear export receptor.OsXPO1shares high protein identity with its functional homologs in Arabidopsis and other organisms.OsXPO1localized to both the nucleus and the cytoplasm,directly interacted with the small GTPases OsRAN1and OsRAN2 in the nucleus,and mediated their nuclear export.Loss-of-function osxpo1 mutations were lethal at the seedling stage.Suppression of OsXPO1 expression in RNA interference lines produced multifaceted developmental defects,including arrested growth,premature senescence,abnormal inflorescence,and brown and mouth-opened spikelets.Overexpression of OsXPO1 in rice reduced plant height and seed-setting rate,but increased plant tolerance in response to PEG-mimicked drought stress and salt stress.These results indicate that OsXPO1 is a nuclear export receptor and acts in regulating plant development and abiotic stress responses.
基金Biological Breeding-National Science and Technology Major Project(2023ZD04072)the National Natural Science Foundation of China(32070265).
文摘In C_(3) plants,photorespiration is an energy expensive pathway that competes with photosynthetic CO_(2) assimilation and releases CO_(2) into the atmosphere,potentially reducing C_(3) plant productivity by 20%-50%.Consequently,reducing the flux through photorespiration has been recognized as a major way to improve C_(3) crop photosynthetic carbon fixation and productivity.While current research efforts in engineering photorespiration are mainly based on the modification of chloroplast glycolate metabolic steps,only limited studies have explored optimizations in other photorespiratory metabolic steps.Here,we engineered an imGS bypass within the rice mitochondria to bypass the photorespiratory glycine toward glycine betaine,thereby,improving the photosynthetic carbon fixation in rice.The imGS transgenic rice plants exhibited significant accumulation of glycine betaine,reduced photorespiration,and elevated photosynthesis and photosynthate levels.Additionally,the introduction of imGS bypass into rice leads to an increase in the number of branches and grains per panicle which may be related to cytokinin and gibberellin signaling pathways.Taken together,these results suggest diverting mitochondrial glycine from photorespiration toward glycine betaine synthesis can effectively enhance carbon fixation and panicle architecture in rice,offering a promising strategy for developing functional mitochondrial photorespiratory bypasses with the potential to enhance plant productivity.
基金supported by Key Realm R&D Program of Guangdong Province(Grant No.2020B0202090005)Special Fund for Scientific Innovation Strategy-construction of High Level Academy of Agriculture Science(Grant No.R2020PY-JG002)the President Foundation of Guangdong Academy of Agricultural Sciences(Grant No.202030)。
文摘Huanglongbing(HLB)is a devastating disease that has led to an acute crisis for growers of citrus,one of the world's most important fruit crops.The phloem-feeding Asian citrus psyllid(ACP),Diaphorina citri,is the main pest at the new shoot stage and is the only natural vector of HLB pathogenic bacteria.Little is known about how plants perceive and defend themselves from this destructive pest.Here,we characterized changes in the expression of various genes in citrus plants that were continuously infested by D.citri for different durations(12,24,and 48 h).A total of 5219 differentially expressed genes(DEGs)and 643 common DEGs were identified across all time points.Several pathways related to defense were activated,such as peroxisome,alpha-linolenic acid metabolism,and phenylpropanoid and terpenoid biosynthesis,and some pathways related to growth and signal transduction were suppressed in response to D.citri infestation.The expression of genes including kinases(CML44,CIPK6,and XTH6),phytohormones(SAMT,LOX6,and NPR3),transcription factors(bHLH162,WRKY70,and WRKY40),and secondary metabolite synthesis-related genes(PAL,4CL2,UGT74B1 and CYP82G1)was significantly altered in response to D.citri infestation.The findings of this study greatly enhance our understanding of the mechanisms underlying the defense response of citrus plants to D.citri infestation at the molecular level.Functional characterization of the candidate defense-related genes identified in this study will aid the molecular breeding of insect-resistant citrus varieties.
基金This work was supported by grants from the National Natural Science Foundation of China(31570250)the Science and Technology Project of Guangzhou City,China(201607020006,201804010377)the Natural Science Foundation of Guangdong Province,China(2015A030313410,2017A030313100).
文摘WD40 repeat-containing proteins(WD40 proteins)serve as versatile scaffolds for protein-protein interac-tions,modulating a variety of cellular processes such as plant stress and hormone responses.Here we report the identification of a WD40 protein,XIW1(for XPO1-interacting WD40 protein 1),which positively regulates the abscisic acid(ABA)response in Arabidopsis.XIW1 is located in the cytoplasm and nucleus.We found that it interacts with the nuclear transport receptor XPO1 and is exported by XPO1 from the nucleus.Mutation of XIW1 reduces the induction of ABA-responsive genes and the accumulation of ABA Insensitive 5(ABI5),causing mutant plants with ABA-insensitive phenotypes during seed germination and seedling growth,and decreased drought stress resistance.ABA treatment upregulates the expression of XIW1,and both ABA and abiotic stresses promote XIW1 accumulation in the nucleus,where it interacts with ABI5.Loss of XIW1 function results in rapid proteasomal degradation of ABI5.Taken together,these findings suggest that XIW1 is a nucleocytoplasmic shuttling protein and plays a positive role in ABA responses by interacting with and maintaining the stability of ABI5 in the nucleus.
基金supported by the National Natural Science Foundation of China (U1201212 31170222)+1 种基金the Shenzhen Overseas Talents Innovation and Entrepreneurship Funding Scheme (The Peacock Scheme)China Postdoctoral Science Foundation (2013M530374)
文摘Mutations in the photorespiration pathway dis- play a lethal phenotype in atmospheric air, which can be fully recovered by elevated C02. An exception is that mutants of peroxisomal hydroxypyruvate reductase （HPR1） do not have this phenotype, indicating the presence of cytosolic bypass in the photorespiration pathway. In this study, we constructed overexpression of the OsHPR1 gene and RNA interference plants of OsHPR1 and OsHPR2 genes in rice （Oryza sativo L. cv. Zhonghua 11）. Results from reverse transcription-polymerase chain reaction （RT-PCR）, Western blot, and enzyme assays showed that HPR1 activity changed significantly in corresponding transgenic lines without any effect on HPR2 activity, which is the same for HPR2. However, metabolite analysis and the serine glyoxylate aminotransferase （SGAT） activity assay showed that the metabolite flux of photorespiration was disturbed in RNAi lines of both HPR genes. Furthermore, HPR1 and HPR2 proteins were located to the peroxisome and cytosol, respectively, by transient expression experiment. Double mutant hprl x hpr2 was generated by crossing individual mutant of hprl and hpr2. The phenotypes of all transgenic lines were determined in ambient air and C02-elevated air. The phenotype typical of photorespiration mutants was observed only where activity of both HPRI and HPR2 were downregulated in the same line. These findings demonstrate that two hydroxypyruvate reductases encoded by OsHPRI and OsHPR2 are involved in photorespiratory metabolism in rice.
基金Supported by the National Natural Science Foundation of China(30700052)the Natural Science Foundation of Guangdong Province (0700680)the Doctoral Program of Guangdong Natural Science Foundation (4600-E09022)
文摘Based on the evidence that Al resistance is an inducible process and rice is an Al-resistant crop, identification of Al-responsive genes from rice may help to further clone Al.resistant genes in plants. Semi-quantitative and real-time polymerase chain reaction （PCR） is widely applied in gene transcrip- tional analyses, particularly for those genes with low transcript abundance. Normalization with proper endogenous control （EC） genes is critical for these two approaches in terms of reliability and precision. We first noticed that the expression of several commonly-used EC genes was depressed under AI stress, while sulfite reductase gene （SR） was stable throughout the AI treatment. The reliability of SR as an EC gene was further tested by analyzing the expression of a number of genes in response to Al challenge. Except for the consistent results obtained for the four previously-identified genes, nine additional genes were newly defined as Al-responsive in this study. Collectively, our results suggest that SR can be used as a novel EC gene for semi-quantitative and real-time PCR analysis of Al responsive genes, and that activated transport of silicon and stimulated metabolism of carotenoid and terpenoid could be involved in Al resistance in rice plants.
