As a complex wall system in flowering plants, the pollen outer wall mainly contains aliphatic sporopollenin; however, the mechanism for synthesizing these lipidic precursors during pollen development remains less well...As a complex wall system in flowering plants, the pollen outer wall mainly contains aliphatic sporopollenin; however, the mechanism for synthesizing these lipidic precursors during pollen development remains less well understood. Here, we report on the function of the rice tapetum-expressing TDR （Tapetum Degeneration Retardation） gene in aliphatic metabolism and its regulatory role during rice pollen development. The observations of transmission electron microscopy （TEM） and scanning electron microscopy （SEM） analyses suggested that pollen wall formation was significantly altered in the tdr mutant. The contents of aliphatic compositions of anther were greatly changed in the tdr mutant revealed by GC-MS （gas chromatography-mass spectrometry） testing, particularly less accumulated in fatty acids, primary alcohols, alkanes and alkenes, and an abnormal increase in secondary alcohols with carbon lengths from C29 to C3S in tdr. Microarray data revealed that a group of genes putatively involved in lipid transport and metabolism were significantly altered in the tdr mutant, indicating the critical role of TDR in the formation of the pollen wall. Also, a wide range of genes （236 in total--154 up-regulated and 82 down-regulated） exhibited statistically significant expressional differences between wild-type and tdr. In addition to its function in promoting tapetum PCD, TDR possibly plays crucial regulatory roles in several basic biological processes during rice pollen development.展开更多
In anther development, tapetal cells take part in complex processes, including endomitosis and apoptosis （programmed cell death）. The tapetum provides many of the proteins, lipids, polysaccharides and other molecule...In anther development, tapetal cells take part in complex processes, including endomitosis and apoptosis （programmed cell death）. The tapetum provides many of the proteins, lipids, polysaccharides and other molecules necessary for pollen development. Several transcription factors, including DYT1, TDF1, AMS, MS188 and MS1, have been reported to be essential for tapetum development and function in Arabidopsis thaliana. Here, we present a detailed cytological analysis of knockout mutants for these genes, along with an in situ RNA hybridization experiment and double mutant analysis showing that these transcription factors form a genetic pathway in tapetum development. DYT1, TDF1 and AMS function in early tapetum development, while MS188 and MS1 are important for late tapetum development. The genetic pathway revealed in this work facilitates further investigation of the function and molecular mechanisms of tapetum development in Arabidopsis.展开更多
Glycerol-3-phosphate acyltransferase （GPAT） mediates the initial synthetic step for the formation of glycer- olipids, which act as the major components of biological membranes and the principal stored forms of energ...Glycerol-3-phosphate acyltransferase （GPAT） mediates the initial synthetic step for the formation of glycer- olipids, which act as the major components of biological membranes and the principal stored forms of energy. GPAT6 is a member of the Arabidopsis GPAT family, which is crucial for cutin biosynthesis in sepals and petals. In this work, a func- tional analysis of GPAT6 in anther development and plant fertility was performed. GPAT6 was highly expressed in the tapetum and microspores during anther development. The knockout mutant, gpat6, caused a massive reduction in seed production. This report shows that the ablation of GPAT6 caused defective tapetum development with reduced endoplas- mic reticulum （ER） profiles in the tapetum, which largely led to the abortion of pollen grains and defective pollen wall formation. In addition, pollen germination and pollen tube elongation were affected in the mutant plants. Furthermore, the double mutant analysis showed that GPAT6 and GPAT1 make joint effects on the release of microspores from tetrads and stamen filament elongation. This work shows that GPAT6 plays multiple roles in stamen development and fertility in Arabidopsis.展开更多
During anther development, the tapetum pro- vides materials and nutrients for pollen development. In Arabidopsis, several transcription factors have been iden- tified to form a genetic pathway （DYT1-TDF1-AMS- MS188-...During anther development, the tapetum pro- vides materials and nutrients for pollen development. In Arabidopsis, several transcription factors have been iden- tified to form a genetic pathway （DYT1-TDF1-AMS- MS188-MS1） for tapetal development and function. DEFECTIVE in TAPETAL DEVELOPMENT and FUNCTION1 （TDF1） is a member of the R2R3 MYB family and is essential for early tapetum development in Arabidopsis. Here, we characterized an ortholog of Ara- bidopsis TDF1 in rice, OsTDF1 （LOC_Os03g18480）. OsTDF1 shares 69 % amino acid sequence identity with AtTDF1 in the putative MYB domain near the N-terminal region. RT-PCR and in situ hybridization show that OsTDF1 is specifically expressed in tapetal cells of rice anthers. The expression of OsTDF1 in Arabidopsis tdfl mutant restores its fertility, suggesting that this homolog can fulfill the normal function of TDF1 in Arabidopsis. The ostdfl knockout mutant exhibits a male-sterile phenotype. Its tapetal cells exhibit a vacuolated and hypertrophic phenotype similar to that of Arabidopsis tdfl mutants. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays revealed OsTDF1 acts as an essential regulator for tapetum programmed cell death. The qRT-PCR analysis revealed that OsTDF1 acts downstream of UDT1 and upstream of TDR, EAT1, OsMYBI03 and PTCI in rice, suggesting that the genetic pathway for tapetum development is generally conserved between rice and Arabidopsis,展开更多
Lily was grown worldwide as a fresh cutting flower because of its colorful petals, but its anther contained a large number of pollen grains that cause serious pollen contamination, however, pollen abortion can effecti...Lily was grown worldwide as a fresh cutting flower because of its colorful petals, but its anther contained a large number of pollen grains that cause serious pollen contamination, however, pollen abortion can effectively reduce the level of pollen pollution. Our analysis aims to use cytological observation to detect the critical stage when pollen abortion occurs and to provide comprehensive gene expression information at the transcriptional level. The result showed that pollen abortion in ‘Little Kiss’ began at the mononuclear stage and the callose that covers the microspores failed to degenerate when young pollens were released from the tetrads. In addition, compared with the normally developed one,the tapetum of ‘Little Kiss’ degraded in advance while the degradation of callose was delayed. Furthermore, 103 differentially expressed genes(DEGs) related to the advance degeneration of tapetum cells and callose were found in the expression levels, including 22 transcription factors(TFs). In particular, two β-glucanase genes(endo-1,3(4)-β-glucanase, exo-β-glucanase) responsible for callose degeneration were significantly down-regulated. These results suggested that pollen abortion may occur at mononuclear stage and that early degeneration of tapetum cells resulted in a significant down-regulation of β-glucanase genes. As a result, the callose to cover microspores impedes the formation of pollen walls, which may possibly lead to pollen abortion.展开更多
Previous reports indicated that AtMYB103 has an important role in tapetum development,callose dissolution,and exine formation in A.thaliana anthers.Here,we further characterized its function in anther development by e...Previous reports indicated that AtMYB103 has an important role in tapetum development,callose dissolution,and exine formation in A.thaliana anthers.Here,we further characterized its function in anther development by expression pattern analysis,transmission electron microscopy observation of the knockout mutant,and microarray analysis of downstream genes.A total of 818 genes differentially expressed between ms188 and the wild-type were identified by global expression profiling analysis.Functional classification showed that loss-of-function of AtMYB103 impairs cell wall modification,lipid metabolic pathways,and signal transduction throughout anther development.RNA in situ hybridization confirmed that transcription factors acting downstream of AtMYB103 (At1g06280 and At1g02040) were expressed in the tapetum and microspores at later stages,suggesting that they might have important roles in microsporogenesis.These results indicated that AtMYB103 is a crucial regulator of Arabidopsis anther development.展开更多
Photoperiod-sensitive genic male-sterile （PSGMS） rice （Oryza sativa L.）, a natural mutant found in the rice cultivar Nongken 58, is very useful for the development of hybrid rice cultivars. Despite its widespread ...Photoperiod-sensitive genic male-sterile （PSGMS） rice （Oryza sativa L.）, a natural mutant found in the rice cultivar Nongken 58, is very useful for the development of hybrid rice cultivars. Despite its widespread use in breeding programs, the initial stage of the abortive development of PSGMS rice and the possible cytological mechanisms of pollen abortion have not been determined. In the present study, a systematic cytological comparison of the anther development of PSGMS rice with its normal fertile counterpart is conducted. The results show that pollen abortion in PSGMS rice first occurs before the pollen mother cell （PMC） stage, and continues during the entire process of pollen development until pollen degradation. The abortive process was closely associated with the abnormal behavior of the tapetum. Although tapetum degeneration in PSGMS rice initiates already at the PMC stage, it proceeds slowly and does not complete until the breakdown of the pollen. Such cytological observations were supported by the results of the TUNEL （TdT-mediated dUTP Nick End Labeling） assay, which detects DNA fragmentation resulting from programmed cell death （PCD）, indicating that the premature tapetum degeneration is in the process of PCD.展开更多
文摘As a complex wall system in flowering plants, the pollen outer wall mainly contains aliphatic sporopollenin; however, the mechanism for synthesizing these lipidic precursors during pollen development remains less well understood. Here, we report on the function of the rice tapetum-expressing TDR （Tapetum Degeneration Retardation） gene in aliphatic metabolism and its regulatory role during rice pollen development. The observations of transmission electron microscopy （TEM） and scanning electron microscopy （SEM） analyses suggested that pollen wall formation was significantly altered in the tdr mutant. The contents of aliphatic compositions of anther were greatly changed in the tdr mutant revealed by GC-MS （gas chromatography-mass spectrometry） testing, particularly less accumulated in fatty acids, primary alcohols, alkanes and alkenes, and an abnormal increase in secondary alcohols with carbon lengths from C29 to C3S in tdr. Microarray data revealed that a group of genes putatively involved in lipid transport and metabolism were significantly altered in the tdr mutant, indicating the critical role of TDR in the formation of the pollen wall. Also, a wide range of genes （236 in total--154 up-regulated and 82 down-regulated） exhibited statistically significant expressional differences between wild-type and tdr. In addition to its function in promoting tapetum PCD, TDR possibly plays crucial regulatory roles in several basic biological processes during rice pollen development.
基金supported by grants from the National Natural Science Foundation of China (30925007)Shanghai(11ZR1425800)the State Key Basic Research and Development Program of China (2007CB947600)
文摘In anther development, tapetal cells take part in complex processes, including endomitosis and apoptosis （programmed cell death）. The tapetum provides many of the proteins, lipids, polysaccharides and other molecules necessary for pollen development. Several transcription factors, including DYT1, TDF1, AMS, MS188 and MS1, have been reported to be essential for tapetum development and function in Arabidopsis thaliana. Here, we present a detailed cytological analysis of knockout mutants for these genes, along with an in situ RNA hybridization experiment and double mutant analysis showing that these transcription factors form a genetic pathway in tapetum development. DYT1, TDF1 and AMS function in early tapetum development, while MS188 and MS1 are important for late tapetum development. The genetic pathway revealed in this work facilitates further investigation of the function and molecular mechanisms of tapetum development in Arabidopsis.
基金This work was supported by grants from the National Science Foundation of China，the National Basic Research Program of China，by the Leading Academic Discipline Project of Shanghai Municipal Education Commission
文摘Glycerol-3-phosphate acyltransferase （GPAT） mediates the initial synthetic step for the formation of glycer- olipids, which act as the major components of biological membranes and the principal stored forms of energy. GPAT6 is a member of the Arabidopsis GPAT family, which is crucial for cutin biosynthesis in sepals and petals. In this work, a func- tional analysis of GPAT6 in anther development and plant fertility was performed. GPAT6 was highly expressed in the tapetum and microspores during anther development. The knockout mutant, gpat6, caused a massive reduction in seed production. This report shows that the ablation of GPAT6 caused defective tapetum development with reduced endoplas- mic reticulum （ER） profiles in the tapetum, which largely led to the abortion of pollen grains and defective pollen wall formation. In addition, pollen germination and pollen tube elongation were affected in the mutant plants. Furthermore, the double mutant analysis showed that GPAT6 and GPAT1 make joint effects on the release of microspores from tetrads and stamen filament elongation. This work shows that GPAT6 plays multiple roles in stamen development and fertility in Arabidopsis.
基金This work was supported by the grants from the Ministry of Science and Technology of China （2013CB945100）, the National Natural Science Foundation of China （31100227）.
文摘During anther development, the tapetum pro- vides materials and nutrients for pollen development. In Arabidopsis, several transcription factors have been iden- tified to form a genetic pathway （DYT1-TDF1-AMS- MS188-MS1） for tapetal development and function. DEFECTIVE in TAPETAL DEVELOPMENT and FUNCTION1 （TDF1） is a member of the R2R3 MYB family and is essential for early tapetum development in Arabidopsis. Here, we characterized an ortholog of Ara- bidopsis TDF1 in rice, OsTDF1 （LOC_Os03g18480）. OsTDF1 shares 69 % amino acid sequence identity with AtTDF1 in the putative MYB domain near the N-terminal region. RT-PCR and in situ hybridization show that OsTDF1 is specifically expressed in tapetal cells of rice anthers. The expression of OsTDF1 in Arabidopsis tdfl mutant restores its fertility, suggesting that this homolog can fulfill the normal function of TDF1 in Arabidopsis. The ostdfl knockout mutant exhibits a male-sterile phenotype. Its tapetal cells exhibit a vacuolated and hypertrophic phenotype similar to that of Arabidopsis tdfl mutants. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays revealed OsTDF1 acts as an essential regulator for tapetum programmed cell death. The qRT-PCR analysis revealed that OsTDF1 acts downstream of UDT1 and upstream of TDR, EAT1, OsMYBI03 and PTCI in rice, suggesting that the genetic pathway for tapetum development is generally conserved between rice and Arabidopsis,
基金supported by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Fundamental Research Funds for the Central Universities(Grant No.KYTZ201602)+1 种基金the High Level Talent Project of the Top Six Talents in Jiangsu(Grant No.NY-077)the earmarked fund for germplasm resources of Nanjing Agricultural University(Grant No.KYZZ201920)。
文摘Lily was grown worldwide as a fresh cutting flower because of its colorful petals, but its anther contained a large number of pollen grains that cause serious pollen contamination, however, pollen abortion can effectively reduce the level of pollen pollution. Our analysis aims to use cytological observation to detect the critical stage when pollen abortion occurs and to provide comprehensive gene expression information at the transcriptional level. The result showed that pollen abortion in ‘Little Kiss’ began at the mononuclear stage and the callose that covers the microspores failed to degenerate when young pollens were released from the tetrads. In addition, compared with the normally developed one,the tapetum of ‘Little Kiss’ degraded in advance while the degradation of callose was delayed. Furthermore, 103 differentially expressed genes(DEGs) related to the advance degeneration of tapetum cells and callose were found in the expression levels, including 22 transcription factors(TFs). In particular, two β-glucanase genes(endo-1,3(4)-β-glucanase, exo-β-glucanase) responsible for callose degeneration were significantly down-regulated. These results suggested that pollen abortion may occur at mononuclear stage and that early degeneration of tapetum cells resulted in a significant down-regulation of β-glucanase genes. As a result, the callose to cover microspores impedes the formation of pollen walls, which may possibly lead to pollen abortion.
基金supported by the National Natural Science Foundation of China (Grant No. 30925007)the National Basic Research Program of China (Grant No. 2007CB947600)
文摘Previous reports indicated that AtMYB103 has an important role in tapetum development,callose dissolution,and exine formation in A.thaliana anthers.Here,we further characterized its function in anther development by expression pattern analysis,transmission electron microscopy observation of the knockout mutant,and microarray analysis of downstream genes.A total of 818 genes differentially expressed between ms188 and the wild-type were identified by global expression profiling analysis.Functional classification showed that loss-of-function of AtMYB103 impairs cell wall modification,lipid metabolic pathways,and signal transduction throughout anther development.RNA in situ hybridization confirmed that transcription factors acting downstream of AtMYB103 (At1g06280 and At1g02040) were expressed in the tapetum and microspores at later stages,suggesting that they might have important roles in microsporogenesis.These results indicated that AtMYB103 is a crucial regulator of Arabidopsis anther development.
基金Supported in part by the State Key Basic Research and Development Plan of China (2007CB108700)the National Key Project of Functional Genomics of Major Plants and Animals, China
文摘Photoperiod-sensitive genic male-sterile （PSGMS） rice （Oryza sativa L.）, a natural mutant found in the rice cultivar Nongken 58, is very useful for the development of hybrid rice cultivars. Despite its widespread use in breeding programs, the initial stage of the abortive development of PSGMS rice and the possible cytological mechanisms of pollen abortion have not been determined. In the present study, a systematic cytological comparison of the anther development of PSGMS rice with its normal fertile counterpart is conducted. The results show that pollen abortion in PSGMS rice first occurs before the pollen mother cell （PMC） stage, and continues during the entire process of pollen development until pollen degradation. The abortive process was closely associated with the abnormal behavior of the tapetum. Although tapetum degeneration in PSGMS rice initiates already at the PMC stage, it proceeds slowly and does not complete until the breakdown of the pollen. Such cytological observations were supported by the results of the TUNEL （TdT-mediated dUTP Nick End Labeling） assay, which detects DNA fragmentation resulting from programmed cell death （PCD）, indicating that the premature tapetum degeneration is in the process of PCD.
