A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold toleran...A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold tolerance （CT） at seedling stage and heat tolerance （HT） at anthesis.Survival rate of seedlings （SRS） and spikelet fertility （SF）,the index traits of CT and HT,showed significant differences between the two parents under stresses.A total of four QTLs （qSRS1,qSRS7,qSRS11a and qSRS11b） for CT were identified on chromosomes 1,7,11,and the Xiushui 09 alleles increased SRS at all loci except qSRS7.Four QTLs for SF were identified on chromosomes 4,5,6,and 11.These QTLs could be classified into two major types based on their behaviors under normal and stress conditions.The first was QTL expressed only under normal condition;and the second QTL was apparently stress induced and only expressed under stress.Among them,two QTLs （qSF4 and qSF6） which reduced the trait difference between heat stress and normal conditions must have contributed to HT because of their obvious contribution to trait stability,and the IR2061 allele at the qSF6 and the Xiushui 09 allele at the qSF4 improved HT,respectively.No similar QTL was found between CT at seedling stage and HT at anthesis.Therefore,it is possible to breed a new variety with CT and HT by pyramiding the favorable CT-and HT-improved alleles at above loci from Xiushui 09 and IR2061,respectively,through marker-assisted selection （MAS）.展开更多
The present study was carried out to illustrate high-efficient detection of quantitative trait loci （QTLs） with selected introgression lines （ILs） and the existence of ＇hidden genes＇ conferring drought tolerance...The present study was carried out to illustrate high-efficient detection of quantitative trait loci （QTLs） with selected introgression lines （ILs） and the existence of ＇hidden genes＇ conferring drought tolerance （DT）. 52 selected DT ILs, derived from BC2Fz population developed by crossing and backcrossing the susceptible recurrent parent （RP） IR64 with the susceptible donor Khazar were planted under irrigation and drought condition. Four important agronomic traits, e.g., grain yield （GY）, heading date （HD）, panicle numbers per plant （PN）, and plant height （PH） were evaluated and 83 SSR polymorphic molecular markers were used for genotypic analysis. Chi-square test based on genetic hitch-hiking and one-way analysis of variances （ANOVA） were used to detect drought-related loci. Nine and 36 loci were detected by chi-square test and one-way ANOVA, respectively. Five common loci were observed by comparing the results of the two methods, among which two QTLs linked with RM7, and RM241 were detected under irrigation condition, both of the favorable alleles were from RP and explained 13% phenotypic variation （PV） for GY and 28% PV for PH, respectively. The other three QTLs linked with RM 163, RM 18, and RM270 were detected under drought condition, the favorable alleles were all from the donor and explained 10, 24, and 19% PV for HD, PH, and PH, respectively. Five common loci were observed by comparing the results of chi-square test and one-way ANOVA including two QTLs （one for GY and one for PH） under irrigation condition and three QTLs （one for HD and two for PH） under drought condition. By combining phenotypic and genotypic analysis, drought escape could be inferred as the main mechanism for drought tolerance in the present study. The results in present study suggested that the selected ILs population analyzed by chi-square test and one-way ANOVA was quite effective for DT QTL detection with low inputs and could also produce useful materials for breeding with wide genetic diversity for drought tolerance.展开更多
A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.This study was designed to determine whether optimized nitrogen(N)fertilization coul...A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.This study was designed to determine whether optimized nitrogen(N)fertilization could fulfill these multiple goals.In two-year experiments,two high yielding‘super’rice cultivars were grown with different N fertilization management regimes,including zero N input,local farmers’practice(LFP)with heavy N inputs,and optimized N fertilization(ONF).In ONF,by reducing N input,increasing planting density,and optimizing the ratio of urea application at different stages,N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels.Compared with LFP,yield and partial factor productivity of applied N(PFP)under ONF were increased(on average)by 1.70 and 13.06%,respectively.ONF increased starch and amylose content,and significantly decreased protein content.The contents of the short chains of A chain(degree of polymerization(DP)6-12)and B1 chain(DP 13-25)of amylopectin were significantly increased under ONF,which resulted in a decrease in the stability of rice starch crystals.ONF increased viscosity values and improved the thermodynamic properties of starch,which resulted in better eating and cooking quality of the rice.Thus,ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency(NUE)at high yield levels.These results will be useful for applications of high quality rice production at high yield levels.展开更多
Salinity is a major factor limiting rice yield in coastal areas of Asia. To facilitate breeding salt tolerant rice varieties, the wholeplant growth duration salt tolerance（ST） was genetically dissected by phenotypin...Salinity is a major factor limiting rice yield in coastal areas of Asia. To facilitate breeding salt tolerant rice varieties, the wholeplant growth duration salt tolerance（ST） was genetically dissected by phenotyping two sets of BC2F5 introgression lines（ILs） for four yield traits under severe natural salt stress and non-stress filed conditions using SSR markers and the methods of advanced backcross QTL（AB-QTL） analysis and selective introgression. Many QTLs affecting four yield traits under salt stress and nonstress conditions were identified, most（〉90%） of which were clustered in 13 genomic regions of the rice genome and involved in complex epistasis. Most QTLs affecting yield traits were differentially expressed under salt stress and non-stress conditions. Our results suggested that genetics complementarily provides an adequate explanation for the hidden genetic diversity for ST observed in both IL populations. Some promising Huanghuazhan（HHZ） ILs with favorable donor alleles at multiple QTLs and significantly improved yield traits under salt stress and non-stress conditions were identified, providing excellent materials and relevant genetic information for improving rice ST by marker-assisted selection（MAS） or genome selection.展开更多
How to overcome yield stagnation is a big challenge to rice breeders. An effective method for quickly developing new cultivars is to further improve an outstanding cultivar. In this study, three advanced backcross pop...How to overcome yield stagnation is a big challenge to rice breeders. An effective method for quickly developing new cultivars is to further improve an outstanding cultivar. In this study, three advanced backcross populations under yield selection that consist of 123 BC2F2：4 introgression lines （ILs） were developed by crossing Minghui 86 （recurrent parent, RP） with three high-yielding varieties （donors）, namely, ZDZ057, Fuhui 838, and Teqing, respectively. The progeny testing allowed the identification of 12 promising ILs that had significantly higher mean grain yields than Minghui 86 in two environments. A total of 55 QTLs that affect grain yield and its related traits were identified, which included 50 QTLs that were detected using the likelihood ratio test based on stepwise regression （RSTEP-LRT） method, and eight grain yield per plant （GY） QTLs were detected using ehi-squared （X2） test. Among these QTLs, five QTLs were simultaneously detected in different populations and 22 QTLs were detected in both environments. The beneficial donor alleles for increased GY and its related traits were identified in 63.6% （35 out of 55） of the QTLs. These promising ILs and QTLs identified will provide the elite breeding materials and genetic information for further improvement of the grain yield for Minghui 86 through pyramiding breeding.展开更多
Rxol cloned from maize is a non-host gene resistant to bacterial leaf streak of rice. pCAMBIA1305-1 with Rxo1 was digested with Sca I and NgoM IV and the double right-border binary vector pMNDRBBin6 was digested with ...Rxol cloned from maize is a non-host gene resistant to bacterial leaf streak of rice. pCAMBIA1305-1 with Rxo1 was digested with Sca I and NgoM IV and the double right-border binary vector pMNDRBBin6 was digested with Hpa I and Xma I. pMNDRBBin6 carrying the gene Rxo1 was acquired by ligation of blunt-end and cohesive end. The results of PCR, restriction enzyme analysis and sequencing indicated that the Rxo1 gene had been cloned into pMNDRBBin6. This double right-border binary vector, named as pMNDRBBin6-Rxol, will play a role in breeding marker-free plants resistant to bacterial leaf streak of rice by genetic transformation.展开更多
A primary physical map of rice chromosome 12 was constructed using marker-based chromosome landing and chromosome walking. A BAC library from IR64 was screened using 84 RFLP markers, 4 STS markers and 6 microsatellite...A primary physical map of rice chromosome 12 was constructed using marker-based chromosome landing and chromosome walking. A BAC library from IR64 was screened using 84 RFLP markers, 4 STS markers and 6 microsatellite markers on chromosome 12 by colony hybridization and polymerase chain reaction (PCR) amplification. A total of 59 contigs consisting of 419 BAC clones including 5 single-clones were physically aligned on rice chromosome 12 with the largest BAC contig covering 855 kb. The whole physical map had a size of ～16 Mb and covered about 52% of rice chromosome 12. This physical map will be certainly helpful for map-based gene cloning of agronomically and biological important genes and understanding the genome structure of the chromosome.展开更多
基金funded by the Project of the 863 Program(2010AA101803)the 948 Program of China(2006-G51 and 2010-G2B)
文摘A set of 240 introgression lines derived from the advanced backcross population of a cross between a japonica cultivar,Xiushui 09,and an indica breeding line,IR2061,was developed to dissect QTLs affecting cold tolerance （CT） at seedling stage and heat tolerance （HT） at anthesis.Survival rate of seedlings （SRS） and spikelet fertility （SF）,the index traits of CT and HT,showed significant differences between the two parents under stresses.A total of four QTLs （qSRS1,qSRS7,qSRS11a and qSRS11b） for CT were identified on chromosomes 1,7,11,and the Xiushui 09 alleles increased SRS at all loci except qSRS7.Four QTLs for SF were identified on chromosomes 4,5,6,and 11.These QTLs could be classified into two major types based on their behaviors under normal and stress conditions.The first was QTL expressed only under normal condition;and the second QTL was apparently stress induced and only expressed under stress.Among them,two QTLs （qSF4 and qSF6） which reduced the trait difference between heat stress and normal conditions must have contributed to HT because of their obvious contribution to trait stability,and the IR2061 allele at the qSF6 and the Xiushui 09 allele at the qSF4 improved HT,respectively.No similar QTL was found between CT at seedling stage and HT at anthesis.Therefore,it is possible to breed a new variety with CT and HT by pyramiding the favorable CT-and HT-improved alleles at above loci from Xiushui 09 and IR2061,respectively,through marker-assisted selection （MAS）.
基金funded by the National Basic Research Program of China (973 Program, 2004CB117204)the Program for Introduction of International Advanced Ag-ricultural Sciences & Technologies from the Ministry of Agriculture of China [948 Progam, 2006-G1(A)]the Project of Rockefeller Foundation, USA (RF2000)
文摘The present study was carried out to illustrate high-efficient detection of quantitative trait loci （QTLs） with selected introgression lines （ILs） and the existence of ＇hidden genes＇ conferring drought tolerance （DT）. 52 selected DT ILs, derived from BC2Fz population developed by crossing and backcrossing the susceptible recurrent parent （RP） IR64 with the susceptible donor Khazar were planted under irrigation and drought condition. Four important agronomic traits, e.g., grain yield （GY）, heading date （HD）, panicle numbers per plant （PN）, and plant height （PH） were evaluated and 83 SSR polymorphic molecular markers were used for genotypic analysis. Chi-square test based on genetic hitch-hiking and one-way analysis of variances （ANOVA） were used to detect drought-related loci. Nine and 36 loci were detected by chi-square test and one-way ANOVA, respectively. Five common loci were observed by comparing the results of the two methods, among which two QTLs linked with RM7, and RM241 were detected under irrigation condition, both of the favorable alleles were from RP and explained 13% phenotypic variation （PV） for GY and 28% PV for PH, respectively. The other three QTLs linked with RM 163, RM 18, and RM270 were detected under drought condition, the favorable alleles were all from the donor and explained 10, 24, and 19% PV for HD, PH, and PH, respectively. Five common loci were observed by comparing the results of chi-square test and one-way ANOVA including two QTLs （one for GY and one for PH） under irrigation condition and three QTLs （one for HD and two for PH） under drought condition. By combining phenotypic and genotypic analysis, drought escape could be inferred as the main mechanism for drought tolerance in the present study. The results in present study suggested that the selected ILs population analyzed by chi-square test and one-way ANOVA was quite effective for DT QTL detection with low inputs and could also produce useful materials for breeding with wide genetic diversity for drought tolerance.
基金financially supported by the National Natural Science Foundation of China (32071943 and 31872853)the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)
文摘A major challenge in modern rice production is to achieve the dual goals of high yield and good quality with low environmental costs.This study was designed to determine whether optimized nitrogen(N)fertilization could fulfill these multiple goals.In two-year experiments,two high yielding‘super’rice cultivars were grown with different N fertilization management regimes,including zero N input,local farmers’practice(LFP)with heavy N inputs,and optimized N fertilization(ONF).In ONF,by reducing N input,increasing planting density,and optimizing the ratio of urea application at different stages,N use efficiency and the physicochemical and textural properties of milled rice were improved at higher yield levels.Compared with LFP,yield and partial factor productivity of applied N(PFP)under ONF were increased(on average)by 1.70 and 13.06%,respectively.ONF increased starch and amylose content,and significantly decreased protein content.The contents of the short chains of A chain(degree of polymerization(DP)6-12)and B1 chain(DP 13-25)of amylopectin were significantly increased under ONF,which resulted in a decrease in the stability of rice starch crystals.ONF increased viscosity values and improved the thermodynamic properties of starch,which resulted in better eating and cooking quality of the rice.Thus,ONF could substantially compensate the negative effects caused by N fertilizer and achieve the multiple goals of higher grain quality and nitrogen use efficiency(NUE)at high yield levels.These results will be useful for applications of high quality rice production at high yield levels.
基金funded by the National High-Tech R&D Program of China (2012AA101101)the 948 Project from the Ministry of Agriculture, China (2010-G2B)+1 种基金the International Cooperative Project from the Ministry of Science and Technology, China (S2012ZR0160)the Bill & Melinda Gates Foundation Project (OPP51587)
文摘Salinity is a major factor limiting rice yield in coastal areas of Asia. To facilitate breeding salt tolerant rice varieties, the wholeplant growth duration salt tolerance（ST） was genetically dissected by phenotyping two sets of BC2F5 introgression lines（ILs） for four yield traits under severe natural salt stress and non-stress filed conditions using SSR markers and the methods of advanced backcross QTL（AB-QTL） analysis and selective introgression. Many QTLs affecting four yield traits under salt stress and nonstress conditions were identified, most（〉90%） of which were clustered in 13 genomic regions of the rice genome and involved in complex epistasis. Most QTLs affecting yield traits were differentially expressed under salt stress and non-stress conditions. Our results suggested that genetics complementarily provides an adequate explanation for the hidden genetic diversity for ST observed in both IL populations. Some promising Huanghuazhan（HHZ） ILs with favorable donor alleles at multiple QTLs and significantly improved yield traits under salt stress and non-stress conditions were identified, providing excellent materials and relevant genetic information for improving rice ST by marker-assisted selection（MAS） or genome selection.
基金funded by the National High-Tech R&D Program of China (2010AA101806)the Bill & Melinda Gates Foundation, USA (OPP51587)
文摘How to overcome yield stagnation is a big challenge to rice breeders. An effective method for quickly developing new cultivars is to further improve an outstanding cultivar. In this study, three advanced backcross populations under yield selection that consist of 123 BC2F2：4 introgression lines （ILs） were developed by crossing Minghui 86 （recurrent parent, RP） with three high-yielding varieties （donors）, namely, ZDZ057, Fuhui 838, and Teqing, respectively. The progeny testing allowed the identification of 12 promising ILs that had significantly higher mean grain yields than Minghui 86 in two environments. A total of 55 QTLs that affect grain yield and its related traits were identified, which included 50 QTLs that were detected using the likelihood ratio test based on stepwise regression （RSTEP-LRT） method, and eight grain yield per plant （GY） QTLs were detected using ehi-squared （X2） test. Among these QTLs, five QTLs were simultaneously detected in different populations and 22 QTLs were detected in both environments. The beneficial donor alleles for increased GY and its related traits were identified in 63.6% （35 out of 55） of the QTLs. These promising ILs and QTLs identified will provide the elite breeding materials and genetic information for further improvement of the grain yield for Minghui 86 through pyramiding breeding.
文摘Rxol cloned from maize is a non-host gene resistant to bacterial leaf streak of rice. pCAMBIA1305-1 with Rxo1 was digested with Sca I and NgoM IV and the double right-border binary vector pMNDRBBin6 was digested with Hpa I and Xma I. pMNDRBBin6 carrying the gene Rxo1 was acquired by ligation of blunt-end and cohesive end. The results of PCR, restriction enzyme analysis and sequencing indicated that the Rxo1 gene had been cloned into pMNDRBBin6. This double right-border binary vector, named as pMNDRBBin6-Rxol, will play a role in breeding marker-free plants resistant to bacterial leaf streak of rice by genetic transformation.
文摘A primary physical map of rice chromosome 12 was constructed using marker-based chromosome landing and chromosome walking. A BAC library from IR64 was screened using 84 RFLP markers, 4 STS markers and 6 microsatellite markers on chromosome 12 by colony hybridization and polymerase chain reaction (PCR) amplification. A total of 59 contigs consisting of 419 BAC clones including 5 single-clones were physically aligned on rice chromosome 12 with the largest BAC contig covering 855 kb. The whole physical map had a size of ～16 Mb and covered about 52% of rice chromosome 12. This physical map will be certainly helpful for map-based gene cloning of agronomically and biological important genes and understanding the genome structure of the chromosome.
