Ogura cytoplasmic male sterility(Ogura CMS)was first identified in wild radish(Raphanus sativus)and resulted in complete pollen abortion.However,the molecular mechanism of Ogura CMS in Chinese cabbage remains unclear....Ogura cytoplasmic male sterility(Ogura CMS)was first identified in wild radish(Raphanus sativus)and resulted in complete pollen abortion.However,the molecular mechanism of Ogura CMS in Chinese cabbage remains unclear.A cytological analysis confirmed nuclear degradation during the late uninucleate stage of pollen development,which diminished by the tricellular stage.Concurrently,tapetal cells exhibited abnormal enlargement and vacuolation starting from the tetrad stage.Serious developmental defects were observed in the pollen wall.During early pollen development,genes associated with cytochrome c and programmed cell death(PCD)were upregulated in the Ogura CMS line,while genes involved in pollen wall mitosis were downregulated.Conversely,at the late stage of pollen development,peroxisome and autophagy-related genes in the Ogura CMS line were upregulated.The mitochondrial orf138 gene mutation triggered the PCD process in tapetal cells,leading to their abnormal enlargement and the degradation of their contents,eventually resulting in vacuolation at the tricellular stage.These tapetal defects hindered the provision of adequate sporopollenin and nutrients to the microspores,consequently leading to abnormal pollen wall development and abnormal mitosis in the microspores.Ultimately,nuclear dispersion commenced during the late uninucleate stage,and autophagy occurred in the late stage of pollen development.Consequently,the plant could not produce functional pollen,resulting in male sterility in Chinese cabbage.Studies of Ogura CMS can promote the production and application of male sterile materials and enrich male sterile resources,which is of great significance for hybrid breeding.展开更多
High-volume fraction silicon particle-reinforced aluminium matrix composites(Si/Al)are increasingly applied in aerospace,radar communications,and large-scale integrated circuits because of their superior thermal condu...High-volume fraction silicon particle-reinforced aluminium matrix composites(Si/Al)are increasingly applied in aerospace,radar communications,and large-scale integrated circuits because of their superior thermal conductivity,wear resistance,and low thermal expansion coefficient.However,the abrasive and adhesive wear caused by the hard silicon reinforcement and the ductile aluminium matrix leads to significant tool wear,decreased machining efficiency,and compromised surface quality.This study combines theoretical analysis and cutting experiments to investigate polycrystalline diamond(PCD)tool wear during milling of 70 vol%Si/Al composite.A key contribution of this work is the development of a tool wear model that incorporates reinforcement particle characteristics,treating them as ellipsoidal structures,which enhances the accuracy of predicting abrasive and adhesive wear mechanisms.The model is based on abrasive and adhesive wear mechanisms,and can analyze the interaction between silicon particles,aluminium matrix,and tool components,thus providing deeper insights into PCD tool wear processes.Experimental validation of the model shows a good agreement with the results,with a mean deviation of approximately 10%.The findings on the tool wear mechanism reveal that,as tool wear progresses,the proportion of abrasive wear increases from 40%in the running-in stage to 75%in the rapid wear stage,while adhesive wear decreases.The optimal machining parameters of 120 m·min^(–1) cutting speed(v_(c))and 0.04 mm·z^(–1) feed rate(f_(z)),result in tool life of 33 min and surface roughness(S_(a))of 2.2μm.The study uncovers the variation patterns of abrasive and adhesive wear during the tool wear process,and the proposed model offers a robust framework for predicting tool wear during the machining of high-volume fraction Si/Al composites.The research findings also offer key insights for optimizing tool selection and machining parameters,advancing both the theoretical understanding and practical application of PCD tool wear.展开更多
基金supported by the China Agricultural Research System(CARS-23-G15)the Innovation Team of Henan Academy of Agricultural Sciences,China(2024TD06)+2 种基金the Autonomous Innovation Project of Henan Academy of Agricultural Sciences,China(2024ZC034)the Joint Research on Agricultural Variety Improvement of Henan Province,China(2022010504)the Key Research&Development Project of Henan Province,China(221111110100)。
文摘Ogura cytoplasmic male sterility(Ogura CMS)was first identified in wild radish(Raphanus sativus)and resulted in complete pollen abortion.However,the molecular mechanism of Ogura CMS in Chinese cabbage remains unclear.A cytological analysis confirmed nuclear degradation during the late uninucleate stage of pollen development,which diminished by the tricellular stage.Concurrently,tapetal cells exhibited abnormal enlargement and vacuolation starting from the tetrad stage.Serious developmental defects were observed in the pollen wall.During early pollen development,genes associated with cytochrome c and programmed cell death(PCD)were upregulated in the Ogura CMS line,while genes involved in pollen wall mitosis were downregulated.Conversely,at the late stage of pollen development,peroxisome and autophagy-related genes in the Ogura CMS line were upregulated.The mitochondrial orf138 gene mutation triggered the PCD process in tapetal cells,leading to their abnormal enlargement and the degradation of their contents,eventually resulting in vacuolation at the tricellular stage.These tapetal defects hindered the provision of adequate sporopollenin and nutrients to the microspores,consequently leading to abnormal pollen wall development and abnormal mitosis in the microspores.Ultimately,nuclear dispersion commenced during the late uninucleate stage,and autophagy occurred in the late stage of pollen development.Consequently,the plant could not produce functional pollen,resulting in male sterility in Chinese cabbage.Studies of Ogura CMS can promote the production and application of male sterile materials and enrich male sterile resources,which is of great significance for hybrid breeding.
基金supported by the National Natural Science Foundation of China(Grant No.52075255)the Jiangsu Provincial Science and Technology Plan(Grant No.BZ2023005).
文摘High-volume fraction silicon particle-reinforced aluminium matrix composites(Si/Al)are increasingly applied in aerospace,radar communications,and large-scale integrated circuits because of their superior thermal conductivity,wear resistance,and low thermal expansion coefficient.However,the abrasive and adhesive wear caused by the hard silicon reinforcement and the ductile aluminium matrix leads to significant tool wear,decreased machining efficiency,and compromised surface quality.This study combines theoretical analysis and cutting experiments to investigate polycrystalline diamond(PCD)tool wear during milling of 70 vol%Si/Al composite.A key contribution of this work is the development of a tool wear model that incorporates reinforcement particle characteristics,treating them as ellipsoidal structures,which enhances the accuracy of predicting abrasive and adhesive wear mechanisms.The model is based on abrasive and adhesive wear mechanisms,and can analyze the interaction between silicon particles,aluminium matrix,and tool components,thus providing deeper insights into PCD tool wear processes.Experimental validation of the model shows a good agreement with the results,with a mean deviation of approximately 10%.The findings on the tool wear mechanism reveal that,as tool wear progresses,the proportion of abrasive wear increases from 40%in the running-in stage to 75%in the rapid wear stage,while adhesive wear decreases.The optimal machining parameters of 120 m·min^(–1) cutting speed(v_(c))and 0.04 mm·z^(–1) feed rate(f_(z)),result in tool life of 33 min and surface roughness(S_(a))of 2.2μm.The study uncovers the variation patterns of abrasive and adhesive wear during the tool wear process,and the proposed model offers a robust framework for predicting tool wear during the machining of high-volume fraction Si/Al composites.The research findings also offer key insights for optimizing tool selection and machining parameters,advancing both the theoretical understanding and practical application of PCD tool wear.
