In this work, analysis of electromigration-induced void morphological evolution in solder interconnects is performed based on mass diffusion theory. The analysis is conducted for three typical experimentally observed ...In this work, analysis of electromigration-induced void morphological evolution in solder interconnects is performed based on mass diffusion theory. The analysis is conducted for three typical experimentally observed void shapes: circular, ellipse, and cardioid. Void morphological evolution is governed by the competition between the electric field and surface capillary force. In the developed model, both the electric field and capillary force on the void's surface are solved analytically. Based on the mass conversation principle, the normal velocity on the void surface during diffusion is obtained. The void morphological evolution behavior is investigated, and a physical model is developed to predict void collapse to a crack or to split into sub-voids under electric current. It is noted that when the electric current is being applied from the horizontal direction, a circular void may either move stably along the electric current direction or collapse to a finger shape, depending on the relative magnitude of the electric current and surface capillary force. However, the elliptical-shaped void will elongate along the electric current direction and finally collapse to the finger shape. On the other hand, the cardioid-shaped void could bifurcate into two sub-voids when the electric current reaches a critical value. The theoretical predictions agree well with the experimental observations.展开更多
An energy approach is proposed to describe the electromigration induced grain rotation under high current density. The driving force is assumed to arise from the grain-boundary energy reduction and increase of the inn...An energy approach is proposed to describe the electromigration induced grain rotation under high current density. The driving force is assumed to arise from the grain-boundary energy reduction and increase of the inner energy from the joule heating. Energy dissipates by the grain boundary diffusion under electromigration and viscous boundary sliding is considered. Based on the conservation of energy production and dissipation, an equilibrium equation is developed to predict the grain rotation rate analytically. It is recognized that the grain rotates with the reducing of electrical resistivity and inversely proportional to the grain length. The theoretical prediction is compared with the experimental data, which shows good accuracy on the rotation trend and the specific rotation rate.展开更多
A mass diffusion model is developed to describe the growth kinetics of Cu6Sn5 intermetallic compounds(IMC)in the Cu-Sn-Cu sandwich structure.The proposed model is based on the local interfacial mass conversation law w...A mass diffusion model is developed to describe the growth kinetics of Cu6Sn5 intermetallic compounds(IMC)in the Cu-Sn-Cu sandwich structure.The proposed model is based on the local interfacial mass conversation law where interfacial Cu/Sn reactions and atomic diffusion are considered.Theoretical analysis shows that the IMC thickness growth is proportional to the square root of the product of the diffusion coefficient and time.The proposed model can explain the polarity effect of electromigration on kinetics of IMC growth where all the parameters have clear physical meaning.The theoretical predictions are compared with experimental results and show reasonable accuracy.展开更多
Continuously increasing global temperatures present great challenges to food security.Grain size,one of the critical components determining grain yield in rice(Oryza sativa L.),is a prime target for genetic breeding.T...Continuously increasing global temperatures present great challenges to food security.Grain size,one of the critical components determining grain yield in rice(Oryza sativa L.),is a prime target for genetic breeding.Thus,there is an immediate need for genetic improvement in rice to maintain grain yield under heat stress.However,quantitative trait loci(QTLs)endowing heat stress tolerance and grain size in rice are extremely rare.Here,we identified a novel negative regulator with pleiotropic effects,Thermo‐Tolerance and grain Length 1(TTL1),from the super pan‐genomic and transcriptomic data.Loss‐of‐function mutations in TTL1 enhanced heat tolerance,and caused an increase in grain size by coordinating cell expansion and proliferation.TTL1 was shown to function as a transcriptional regulator and localized to the nucleus and cell membrane.Furthermore,haplotype analysis showed that hapL and hapS of TTL1 were obviously correlated with variations of thermotolerance and grain size in a core collection of cultivars.Genome evolution analysis of available rice germplasms suggested that TTL1 was selected during domestication of the indica and japonica rice subspecies,but still had much breeding potential for increasing grain length and thermotolerance.These findings provide insights into TTL1 as a novel potential target for the development of high‐yield and thermotolerant rice varieties.展开更多
Grain size determines grain weight and affects grain quality. Several major quantitative trait loci （QTLs） regulating grain size have been cloned; however, our understanding of the underlying mechanism that regulate...Grain size determines grain weight and affects grain quality. Several major quantitative trait loci （QTLs） regulating grain size have been cloned; however, our understanding of the underlying mechanism that regulates the size of rice grains remains fragmentary. Here, we report the cloning and characterization of a dominant QTL, GRAIN SIZE ON CHROMOSOME 2 （GS2）, which encodes Growth-Regulating Factor 4 （OsGRF4）, a transcriptional regulator. GS2 localizes to the nucleus and may act as a transcription activator. A rare mutation of GS2 affecting the binding site of a microRNA, OsmiR396c, causes elevated expression of GS2/OsGRF4. The increase in GS2 expression leads to larger cells and increased numbers of cells, which thus enhances grain weight and yield. The introduction of this rare allele of GS2/OsGRF4 into rice cultivars could significantly enhance grain weight and increase grain yield, with possible applications in breeding high-yield rice varieties.展开更多
Plant architecture is a complex agronomic trait and a major factor of crop yield,which is affected by several important hormones.Strigolactones(SLs)are identified as a new class hormoneinhibiting branching in many pla...Plant architecture is a complex agronomic trait and a major factor of crop yield,which is affected by several important hormones.Strigolactones(SLs)are identified as a new class hormoneinhibiting branching in many plant species and have been shown to be involved in various developmental processes.Genetical and chemical modulation of the SL pathway is recognized as a promising approach to modify plant architecture.However,whether and how the genes involved in the SL pathway could be utilized in breeding still remain elusive.Here,we demonstrate that a partial loss-of-function allele of the SL biosynthesis gene,HIGH TILLERING AND DWARF 1/DWARF17(HTD1/D17),which encodes CAROTENOID CLEAVAGE DIOXYGENASE 7(CCD7),increases tiller number and improves grain yield in rice.We found that the HTD1 gene had been widely utilized and co-selected with Semidwarf 1(SD1),both contributing to the improvement of plant architecture in modern rice varieties since the Green Revolution in the 1960s.Understanding how phytohormone pathway genes regulate plant architecture and how they have been utilized and selected in breeding will lay the foundation for developing the rational approaches toward improving crop yield.展开更多
High-quality and disease-resistant male sterile lines have great potential for applications in hybrid rice breeding.We introduced specific mutations into the TMS5,Pi21,and Xa13 genes in Pinzhan intermediate breeding m...High-quality and disease-resistant male sterile lines have great potential for applications in hybrid rice breeding.We introduced specific mutations into the TMS5,Pi21,and Xa13 genes in Pinzhan intermediate breeding material using the CRISPR/Cas9 multiplex genome editing system.We found that the transgenefree homozygous triple tms5/pi21/xa13 mutants obtained in the T1 generation displayed characteristics of thermosensitive genic male sterility(TGMS)with enhancedresistance to rice blast and bacterial blight.Our study provides a convenient and effective way of converting breeding intermediate material into TGMS lines through multiplex gene editing,which could significantly accelerate the breeding of sterile lines.展开更多
Plant height and tillering are crucial factors determining rice plant architecture and influencing rice grain production. In this study, multi-tillering dwarf1(mtd1), a stable multi-tiller and dwarf mutant, was screen...Plant height and tillering are crucial factors determining rice plant architecture and influencing rice grain production. In this study, multi-tillering dwarf1(mtd1), a stable multi-tiller and dwarf mutant, was screened from the ethylmethane sulfonate-treated japonica rice variety Wuyunging7. Compared with the wild type, mtd1 mutant exhibited pleiotropic phenotypes, including dwarfism, more tillers, brittle culms and delayed heading date.By employing map-based cloning strategy, the gene MTD1 was finally mapped to an approximately 66-kb region on the short arm of chromosome 9. Sequencing results showed that the gene LOC_Os09g02650(BC12) in mtd1 mutant had a single nucleotide substitution(G to A), which generated a premature translation stop. Over-expressing MTD1/BC12 coding sequence rescued all the phenotypes of mtd1 mutants including plant height and tillers, which confirms that BC12 is the mutated gene in mtd1 mutant.Quantitative reverse transcription-PCR analysis showed that MTD1/BC12 could negatively regulate the expression of MONOCULM 1, IDEAL PLANT ARCHITECTURE1 and Tillering and Dwarf 1, and control rice tillering. Remarkably, a-amylase activity analysis and gibberellic acid(GA)treatment showed that the dwarf phenotype of mtd1 mutant was dependent on GA biosynthesis pathway. These results facilitated to further uncover the molecular mechanism of the growth and development in rice.展开更多
High-quality rice reference genomes have accelerated the comprehensive identification of genome-wide variations and research on functional genomics and breeding.Tian-you-hua-zhan has been a leading hybrid in China ove...High-quality rice reference genomes have accelerated the comprehensive identification of genome-wide variations and research on functional genomics and breeding.Tian-you-hua-zhan has been a leading hybrid in China over the past decade.Here,de novo genome assembly strategy optimization for the rice indica lines Huazhan(HZ)and Tianfeng(TF),including sequencing platforms,assembly pipelines and sequence depth,was carried out.The PacBio and Nanopore platforms for long-read se-quencing were utilized,with the Canu,wtdbg2,SMARTdenovo,Flye,Canu-wtdbg2,Canu-SMARTdenovo and Canu-Flye assemblers.The combination of PacBio and Canu was optimal,considering the contig N50 length,contig number,assembled genome size and polishing process.The assembled contigs were scaffolded with Hi-C data,resulting in two“golden quality”rice reference genomes,and evaluated using the scaffold N50,BUSCO,and LTR assembly index.Furthermore,42,625 and 41,815 non-transposable element genes were annotated for HZ and TF,respectively.Based on our assembly of HZ and TF,as well as Zhenshan97,Minghui63,Shuhui498 and 9311,comprehensive variations were identified using Nipponbare as a reference.The de novo assembly strategy for rice we optimized and the“golden quality”rice genomes we produced for HZ and TF will benefit rice genomics and breeding research,especially with respect to uncovering the genomic basis of the elite traits of HZ and TF.展开更多
Drought is the leading environmental threat affecting crop productivity,and plants have evolved a series of mechanisms to adapt to drought stress.The FT-interacting proteins(FTIPs)and phosphatidylethanola mine.binding...Drought is the leading environmental threat affecting crop productivity,and plants have evolved a series of mechanisms to adapt to drought stress.The FT-interacting proteins(FTIPs)and phosphatidylethanola mine.binding proteins(PEBPs)play key roles in developmental processes,whereas their roles in the regulation of stress response are still largely unknown.Here,we report that OsFTIP1 negatively regulates drought response in rice.We showed that OsFTIP1 interacts with rice MOTHER OF FT AND TFL1(OsMFT1),a PEBP that promotes rice tolerance to drought treatment.Further studies discovered that OsMFT1 interacts with two key drought-related transcription factors,OsbZIP66 and OsMYB26,regulating their binding capacity on drought-related genes and thereby enhancing drought toleranee in rice.Interestingly,we found that OsFTIP1 impedes the nucleocytoplasmic translocation of OsMFT1,implying that dynamic modulation of drought-responsive genes by the OsMFT1-OsMYB26 and OsMFT1-OsbZIP66 complexes is integral to OsFTIP1-modulated nuclear accumulation of OsMFT1.Our findings also suggest that OsMFT1 might act as a hitherto unknown nucleocytoplasmic trafficking signal that regulates drought tolerance in rice in response to environmental signals.展开更多
An energy approach is proposed to describe electromigration induced void nucleation based on phase transformation theory.The chemical potential for an individual migrated atom is predicted by diffusion induced back st...An energy approach is proposed to describe electromigration induced void nucleation based on phase transformation theory.The chemical potential for an individual migrated atom is predicted by diffusion induced back stress equivalent principle.After determining the chemical potential for the dilfusing atoms,the Gibbs free energy controlling the void nucleation can be determined and the mass diffusion process is considered.The critical void radius and nucleation time are determined analytically when the Gibbs free energy approaches the extreme value.The theoretical predictions are compared with the experimental results from literatures and show good accuracy.The proposed model can also be applied to other diffusion induced damage processes such as thermomigration and stress migration.展开更多
基金supported by the National Natural Science Foundation of China (Grant 11572249)the Aerospace Technology Foundation (Grant N2014KC0068)the Aeronautical Science Foundation of China (Grant N2014KC0073)
文摘In this work, analysis of electromigration-induced void morphological evolution in solder interconnects is performed based on mass diffusion theory. The analysis is conducted for three typical experimentally observed void shapes: circular, ellipse, and cardioid. Void morphological evolution is governed by the competition between the electric field and surface capillary force. In the developed model, both the electric field and capillary force on the void's surface are solved analytically. Based on the mass conversation principle, the normal velocity on the void surface during diffusion is obtained. The void morphological evolution behavior is investigated, and a physical model is developed to predict void collapse to a crack or to split into sub-voids under electric current. It is noted that when the electric current is being applied from the horizontal direction, a circular void may either move stably along the electric current direction or collapse to a finger shape, depending on the relative magnitude of the electric current and surface capillary force. However, the elliptical-shaped void will elongate along the electric current direction and finally collapse to the finger shape. On the other hand, the cardioid-shaped void could bifurcate into two sub-voids when the electric current reaches a critical value. The theoretical predictions agree well with the experimental observations.
基金supported by the National Natural Science Foundation of China(Grants 11572249 and 11772257)
文摘An energy approach is proposed to describe the electromigration induced grain rotation under high current density. The driving force is assumed to arise from the grain-boundary energy reduction and increase of the inner energy from the joule heating. Energy dissipates by the grain boundary diffusion under electromigration and viscous boundary sliding is considered. Based on the conservation of energy production and dissipation, an equilibrium equation is developed to predict the grain rotation rate analytically. It is recognized that the grain rotates with the reducing of electrical resistivity and inversely proportional to the grain length. The theoretical prediction is compared with the experimental data, which shows good accuracy on the rotation trend and the specific rotation rate.
基金The authors would like to acknowledge the financial support by the National Natural Science Foundation of China(Grants 11572249 and 11772257)the Fundamental Research Funds for the Central Universities(Grant G2019KY05212).
文摘A mass diffusion model is developed to describe the growth kinetics of Cu6Sn5 intermetallic compounds(IMC)in the Cu-Sn-Cu sandwich structure.The proposed model is based on the local interfacial mass conversation law where interfacial Cu/Sn reactions and atomic diffusion are considered.Theoretical analysis shows that the IMC thickness growth is proportional to the square root of the product of the diffusion coefficient and time.The proposed model can explain the polarity effect of electromigration on kinetics of IMC growth where all the parameters have clear physical meaning.The theoretical predictions are compared with experimental results and show reasonable accuracy.
基金This work was supported by the National Natural Science Foundation of Fujian Province(2022J01470)the Youth Innovation of Chinese Academy of Agricultural Sciences(Y20230C36)+1 种基金the Special Project for Public Welfare Research Institute of Fujian Province(2021R1027005)the Freely Exploring Technological Innovation Projects of Fujian Academy of Agricultural Sciences(ZYTS202216).
文摘Continuously increasing global temperatures present great challenges to food security.Grain size,one of the critical components determining grain yield in rice(Oryza sativa L.),is a prime target for genetic breeding.Thus,there is an immediate need for genetic improvement in rice to maintain grain yield under heat stress.However,quantitative trait loci(QTLs)endowing heat stress tolerance and grain size in rice are extremely rare.Here,we identified a novel negative regulator with pleiotropic effects,Thermo‐Tolerance and grain Length 1(TTL1),from the super pan‐genomic and transcriptomic data.Loss‐of‐function mutations in TTL1 enhanced heat tolerance,and caused an increase in grain size by coordinating cell expansion and proliferation.TTL1 was shown to function as a transcriptional regulator and localized to the nucleus and cell membrane.Furthermore,haplotype analysis showed that hapL and hapS of TTL1 were obviously correlated with variations of thermotolerance and grain size in a core collection of cultivars.Genome evolution analysis of available rice germplasms suggested that TTL1 was selected during domestication of the indica and japonica rice subspecies,but still had much breeding potential for increasing grain length and thermotolerance.These findings provide insights into TTL1 as a novel potential target for the development of high‐yield and thermotolerant rice varieties.
文摘Grain size determines grain weight and affects grain quality. Several major quantitative trait loci （QTLs） regulating grain size have been cloned; however, our understanding of the underlying mechanism that regulates the size of rice grains remains fragmentary. Here, we report the cloning and characterization of a dominant QTL, GRAIN SIZE ON CHROMOSOME 2 （GS2）, which encodes Growth-Regulating Factor 4 （OsGRF4）, a transcriptional regulator. GS2 localizes to the nucleus and may act as a transcription activator. A rare mutation of GS2 affecting the binding site of a microRNA, OsmiR396c, causes elevated expression of GS2/OsGRF4. The increase in GS2 expression leads to larger cells and increased numbers of cells, which thus enhances grain weight and yield. The introduction of this rare allele of GS2/OsGRF4 into rice cultivars could significantly enhance grain weight and increase grain yield, with possible applications in breeding high-yield rice varieties.
基金This work was supported by the National Key Research and Development Program of China(grant no.2016YFpO101801)National Natural Science Foundation of China(grant nos.91735304,31971921,31601285)+1 种基金Natural Science Foundation of Zhejiang Province(grant no.LR20C130001)Shenzhen Peacock Plan(grant no.KQTD2016113010482651)。
文摘Plant architecture is a complex agronomic trait and a major factor of crop yield,which is affected by several important hormones.Strigolactones(SLs)are identified as a new class hormoneinhibiting branching in many plant species and have been shown to be involved in various developmental processes.Genetical and chemical modulation of the SL pathway is recognized as a promising approach to modify plant architecture.However,whether and how the genes involved in the SL pathway could be utilized in breeding still remain elusive.Here,we demonstrate that a partial loss-of-function allele of the SL biosynthesis gene,HIGH TILLERING AND DWARF 1/DWARF17(HTD1/D17),which encodes CAROTENOID CLEAVAGE DIOXYGENASE 7(CCD7),increases tiller number and improves grain yield in rice.We found that the HTD1 gene had been widely utilized and co-selected with Semidwarf 1(SD1),both contributing to the improvement of plant architecture in modern rice varieties since the Green Revolution in the 1960s.Understanding how phytohormone pathway genes regulate plant architecture and how they have been utilized and selected in breeding will lay the foundation for developing the rational approaches toward improving crop yield.
基金supported by the National Natural Science Foundation of China(31601285)the Central Public-interest Scientific Institution Basal Research Fund of China National Rice Research Institute(2017RG002-4)
文摘High-quality and disease-resistant male sterile lines have great potential for applications in hybrid rice breeding.We introduced specific mutations into the TMS5,Pi21,and Xa13 genes in Pinzhan intermediate breeding material using the CRISPR/Cas9 multiplex genome editing system.We found that the transgenefree homozygous triple tms5/pi21/xa13 mutants obtained in the T1 generation displayed characteristics of thermosensitive genic male sterility(TGMS)with enhancedresistance to rice blast and bacterial blight.Our study provides a convenient and effective way of converting breeding intermediate material into TGMS lines through multiplex gene editing,which could significantly accelerate the breeding of sterile lines.
基金supported by the National Natural Science Foundation of China (31401464, 31201183)Zhejiang Provincial Natural Science Foundation of China (Y3110194, LY16C130001)+1 种基金China Postdoctoral Science Foundation (2014M561108)the Open Foundation from Zhejiang Provincial Top Key Discipline of Biology (KFJJ2014006)
文摘Plant height and tillering are crucial factors determining rice plant architecture and influencing rice grain production. In this study, multi-tillering dwarf1(mtd1), a stable multi-tiller and dwarf mutant, was screened from the ethylmethane sulfonate-treated japonica rice variety Wuyunging7. Compared with the wild type, mtd1 mutant exhibited pleiotropic phenotypes, including dwarfism, more tillers, brittle culms and delayed heading date.By employing map-based cloning strategy, the gene MTD1 was finally mapped to an approximately 66-kb region on the short arm of chromosome 9. Sequencing results showed that the gene LOC_Os09g02650(BC12) in mtd1 mutant had a single nucleotide substitution(G to A), which generated a premature translation stop. Over-expressing MTD1/BC12 coding sequence rescued all the phenotypes of mtd1 mutants including plant height and tillers, which confirms that BC12 is the mutated gene in mtd1 mutant.Quantitative reverse transcription-PCR analysis showed that MTD1/BC12 could negatively regulate the expression of MONOCULM 1, IDEAL PLANT ARCHITECTURE1 and Tillering and Dwarf 1, and control rice tillering. Remarkably, a-amylase activity analysis and gibberellic acid(GA)treatment showed that the dwarf phenotype of mtd1 mutant was dependent on GA biosynthesis pathway. These results facilitated to further uncover the molecular mechanism of the growth and development in rice.
基金the Agricultural Science and Technology Innovation Program,the Elite Young Scientists Program of CAAS,the Science Technology and Innovation Committee of Shenzhen Municipality(KQJSCX20180323140312935,AGIS-ZDKY202004)the Dapeng New District Special Fund for Industrial Development(KY20150113)。
文摘High-quality rice reference genomes have accelerated the comprehensive identification of genome-wide variations and research on functional genomics and breeding.Tian-you-hua-zhan has been a leading hybrid in China over the past decade.Here,de novo genome assembly strategy optimization for the rice indica lines Huazhan(HZ)and Tianfeng(TF),including sequencing platforms,assembly pipelines and sequence depth,was carried out.The PacBio and Nanopore platforms for long-read se-quencing were utilized,with the Canu,wtdbg2,SMARTdenovo,Flye,Canu-wtdbg2,Canu-SMARTdenovo and Canu-Flye assemblers.The combination of PacBio and Canu was optimal,considering the contig N50 length,contig number,assembled genome size and polishing process.The assembled contigs were scaffolded with Hi-C data,resulting in two“golden quality”rice reference genomes,and evaluated using the scaffold N50,BUSCO,and LTR assembly index.Furthermore,42,625 and 41,815 non-transposable element genes were annotated for HZ and TF,respectively.Based on our assembly of HZ and TF,as well as Zhenshan97,Minghui63,Shuhui498 and 9311,comprehensive variations were identified using Nipponbare as a reference.The de novo assembly strategy for rice we optimized and the“golden quality”rice genomes we produced for HZ and TF will benefit rice genomics and breeding research,especially with respect to uncovering the genomic basis of the elite traits of HZ and TF.
基金supported by the National Natural Science Foundation of China(32070209 and 32000213)the Zhejiang Provincial Natural Science Foundation of China(LR21C130001 and LQ21C020003)+2 种基金the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2019R01002)the Key Research and Development Program of Zhejiang(2020C02002)the Singapore National Research Foundation Investigatorship Program(NRF-NRFI2016-02).
文摘Drought is the leading environmental threat affecting crop productivity,and plants have evolved a series of mechanisms to adapt to drought stress.The FT-interacting proteins(FTIPs)and phosphatidylethanola mine.binding proteins(PEBPs)play key roles in developmental processes,whereas their roles in the regulation of stress response are still largely unknown.Here,we report that OsFTIP1 negatively regulates drought response in rice.We showed that OsFTIP1 interacts with rice MOTHER OF FT AND TFL1(OsMFT1),a PEBP that promotes rice tolerance to drought treatment.Further studies discovered that OsMFT1 interacts with two key drought-related transcription factors,OsbZIP66 and OsMYB26,regulating their binding capacity on drought-related genes and thereby enhancing drought toleranee in rice.Interestingly,we found that OsFTIP1 impedes the nucleocytoplasmic translocation of OsMFT1,implying that dynamic modulation of drought-responsive genes by the OsMFT1-OsMYB26 and OsMFT1-OsbZIP66 complexes is integral to OsFTIP1-modulated nuclear accumulation of OsMFT1.Our findings also suggest that OsMFT1 might act as a hitherto unknown nucleocytoplasmic trafficking signal that regulates drought tolerance in rice in response to environmental signals.
基金support by the National Natural Science Foundation of China(Grant 11772257)Natural Science Foundation of Shaanxi Providence(Grant 2020JM-103)Fundamental Research Funds for the Central Universities(Grant G2019KY05212).
文摘An energy approach is proposed to describe electromigration induced void nucleation based on phase transformation theory.The chemical potential for an individual migrated atom is predicted by diffusion induced back stress equivalent principle.After determining the chemical potential for the dilfusing atoms,the Gibbs free energy controlling the void nucleation can be determined and the mass diffusion process is considered.The critical void radius and nucleation time are determined analytically when the Gibbs free energy approaches the extreme value.The theoretical predictions are compared with the experimental results from literatures and show good accuracy.The proposed model can also be applied to other diffusion induced damage processes such as thermomigration and stress migration.
