The grain yield of maize has increased continuously in past decades, largely through hybrid innovation, cultivation tech-nology, and in particular, recent genetic improvements in photosynthesis. Elite inbred lines are...The grain yield of maize has increased continuously in past decades, largely through hybrid innovation, cultivation tech-nology, and in particular, recent genetic improvements in photosynthesis. Elite inbred lines are crucial for innovating new germplasm. Here, we analyzed variations in grain yield and a series of eco-physiological photosynthetic traits after anthesis in sixteen parental lines of maize (Zea mays L.) released during three different eras (1960s, 1980s, 2000s). We found that grain yield and biomass signiifcantly increased in the 2000s than those in the 1980s and 1960s. Leaf area, chlorophyl , and soluble protein content slowly decreased, and maintained a higher net photosynthesis rate (Pn) and improved stomatal conductance (Gs) after anthesis in the 2000s. In addition, the parental lines in the 2000s obtained higher actual photo-chemistry efifciency (ФPSI ) and the maximum PSII photochemistry efifciency (Fv/Fm), which largely improved light partition-ing and chlorophyl lfuorescence characteristic, including higher photochemical and photosystem II (PSII) reaction center activity, lower thermal energy dissipation in antenna proteins. Meanwhile, more lamel ae per granum within chloroplasts were observed in the parental lines of the 2000s, with a clear and complete chloroplast membrane, which wil greatly help to improve photosynthetic capacity and energy efifciency of ear leaf in maize parental lines. It is concluded that grain yield increase in modern maize parental lines is mainly attributed to the improved chloroplast structure and more light energy catched for the photochemical reaction, thus having a better stay-green characteristic and stronger photosynthetic capac-ity after anthesis. Our direct physiological evaluation of these inbred lines provides important information for the further development of promising maize cultivars.展开更多
The development of resistant varieties and hybrid combinations has been the most effective and economical strategy to control blast disease caused by Magnaporthe oryzae.However, the distribution of major R genes and b...The development of resistant varieties and hybrid combinations has been the most effective and economical strategy to control blast disease caused by Magnaporthe oryzae.However, the distribution of major R genes and blast resistance characterization in hybrid rice parents has not been well investigated, resulting in their limited use in hybrid rice blast-resistance breeding. In the present study, 88 elite indica hybrid rice parental lines were evaluated with 30 isolates of M. oryzae collected from the main planting area of indica hybrid rice in China and were characterized for the presence of 11 major resistance genes using molecular markers. The pathogenicity assays showed that four types of hybrid rice parent line showed some resistance to M. oryzae. However, the proportions of highly resistant lines and the mean resistance frequency(RF) varied among the four types, with resistance in decreasing order shown by three-line restorer lines, three-line maintainer lines, two-line sterile lines, and two-line restorer lines. All 88 hybrid rice parental lines carried more than one R gene, but none carried the R genes Pi1 and Pi2. Although Pid3 and Pi9 were present only in three-line restorer lines and Pigm only in three-line maintainer lines, the remaining six R genes(Pib, Pid2, Pi5, Pia, Pi54, and Pita) were present in the four types of hybrid rice parent with significantly different distribution frequencies. The correlation between R genes and resistance reactions was investigated. The results are expected to provide useful information for rational utilization of major R genes in hybrid rice breeding programs.展开更多
Over the past seven decades, the grain yield of maize(Zea mays L.) has increased continuously in China, mostly due to hybridization innovations, particularly recent genetic improvements in photosynthesis. In order to ...Over the past seven decades, the grain yield of maize(Zea mays L.) has increased continuously in China, mostly due to hybridization innovations, particularly recent genetic improvements in photosynthesis. In order to reveal photosynthetic characters of elite inbred lines in different ears, a field experiment was conducted at the North China Plain of Shandong Province in China. Six parental lines of maize introduced in three eras(the 1960 s, 1980 s, and 2000 s) were investigated diurnal variation of gas exchange, chlorophyll fluorescence, and photosynthetic response characteristic at the grain filling stage. Compared to earlier parental lines, the 2000 s parental lines always had higher net photosynthetic rate(Pn) throughout the day, especially at noon, and a mid-day depression in Pn did not occur in all hybrids parental lines. Moreover, the stomatal conductance(Gs) and water use efficiency(WUE) of the 2000 s’ lines showed higher value than those of the 1960 s’ and 1980 s’ lines. The inbred lines differences in photosynthetic parameters were partly owing to their different quantum carboxylation efficiencies and light synthase activities. Simultaneously, the 2000 s parental lines exhibited lower light and CO2 compensation points, and their higher apparent quantum yield, and carboxylation efficiency. These suggested that the modern parental lines required lower light intensity and less CO2 to maintain a relatively high photosynthetic capacity, substantially increasing leaf physical quality and stress resistance. It provided crucial information of high photo-efficiency and stress-resistance breeding in maize.展开更多
The amount of root bleeding sap, contents of chlorophyl , nutrients and hormones in flag leaves of a super-hybrid rice cultivar Liangyoupeijiu （LYPJ） and its parents 9311 and Pei’ai 64S after heading were measured ...The amount of root bleeding sap, contents of chlorophyl , nutrients and hormones in flag leaves of a super-hybrid rice cultivar Liangyoupeijiu （LYPJ） and its parents 9311 and Pei’ai 64S after heading were measured in this study. The re-sults revealed that compared with 9311, the chlorophyl content of LYPJ reduced more quickly after heading, and then kept at a lower level, which was an obvious characteristic of premature senescence. The other physiological indices of LYPJ af-ter heading except abscisic acid （ABA） content in leaf and root also maintained at a lower level than 9311, while al the physiological indices of the sterile line Pei＇ai 64S were lower than LYPJ. So it was speculated that the early-aging characteristic of LYPJ may be inherited from Pei’ai 64S. Al the leaf and root early-aging traits reduced for LYPJ and its parent lines after heading, their leaf and root aged grad-ual y, which indicated that the above-ground （leaf） and under-ground （root） parts cor-related to each other closely, but there was not absolute correlations between them judged from the data.展开更多
The genetic diversity of 41 parental lines popularized in commercial hybrid rice production in China was studied by using cluster analysis of morphological traits and simple sequence repeat （SSR） markers. Forty-one ...The genetic diversity of 41 parental lines popularized in commercial hybrid rice production in China was studied by using cluster analysis of morphological traits and simple sequence repeat （SSR） markers. Forty-one entries were assigned into two clusters （i.e. early or medium-maturing cluster; medium or late-maturing cluster） and further assigned into six sub-clusters based on morphological trait cluster analysis, The early or medium-maturing cluster was composed of 15 maintainer lines, four early-maturing restorer lines and two thermo-sensitive genic male sterile lines, and the medium or late-maturing cluster included 16 restorer lines and 4 medium or late-maturing maintainer lines. Moreover, the SSR cluster analysis classified 41 entries into two groups （i.e, maintainer line group and restorer line group） and seven sub-groups. The maintainer line group consisted of all 19 maintainer lines, two thermo-sensitive genic male sterile lines, while the restorer line group was composed of all 20 restorer lines. The SSR analysis fitted better with the pedigree information. From the views on hybrid rice breeding, the results suggested that SSR analysis might be a better method to study the diversity of parental lines in indica hybrid rice.展开更多
基金financial support from the National Natural Science Foundation of China (31401342)the National Basic Research Program of China (973 Program, 2015CB150401)
文摘The grain yield of maize has increased continuously in past decades, largely through hybrid innovation, cultivation tech-nology, and in particular, recent genetic improvements in photosynthesis. Elite inbred lines are crucial for innovating new germplasm. Here, we analyzed variations in grain yield and a series of eco-physiological photosynthetic traits after anthesis in sixteen parental lines of maize (Zea mays L.) released during three different eras (1960s, 1980s, 2000s). We found that grain yield and biomass signiifcantly increased in the 2000s than those in the 1980s and 1960s. Leaf area, chlorophyl , and soluble protein content slowly decreased, and maintained a higher net photosynthesis rate (Pn) and improved stomatal conductance (Gs) after anthesis in the 2000s. In addition, the parental lines in the 2000s obtained higher actual photo-chemistry efifciency (ФPSI ) and the maximum PSII photochemistry efifciency (Fv/Fm), which largely improved light partition-ing and chlorophyl lfuorescence characteristic, including higher photochemical and photosystem II (PSII) reaction center activity, lower thermal energy dissipation in antenna proteins. Meanwhile, more lamel ae per granum within chloroplasts were observed in the parental lines of the 2000s, with a clear and complete chloroplast membrane, which wil greatly help to improve photosynthetic capacity and energy efifciency of ear leaf in maize parental lines. It is concluded that grain yield increase in modern maize parental lines is mainly attributed to the improved chloroplast structure and more light energy catched for the photochemical reaction, thus having a better stay-green characteristic and stronger photosynthetic capac-ity after anthesis. Our direct physiological evaluation of these inbred lines provides important information for the further development of promising maize cultivars.
基金supported by the Key Research and Development Project of Jiangsu Province for Modern Agriculture (BE2015336)the "333" Project of Jiangsu Province, China (BRA2016145)+2 种基金the Natural Science Foundation for Young Scientists of Jiangsu Province, China (BK20160447)the Natural Science Foundation for Young Scientists of Yangzhou, Jiangsu Province, China (YZ2016103)Yangzhou international technology cooperation project (YZ2015145)
文摘The development of resistant varieties and hybrid combinations has been the most effective and economical strategy to control blast disease caused by Magnaporthe oryzae.However, the distribution of major R genes and blast resistance characterization in hybrid rice parents has not been well investigated, resulting in their limited use in hybrid rice blast-resistance breeding. In the present study, 88 elite indica hybrid rice parental lines were evaluated with 30 isolates of M. oryzae collected from the main planting area of indica hybrid rice in China and were characterized for the presence of 11 major resistance genes using molecular markers. The pathogenicity assays showed that four types of hybrid rice parent line showed some resistance to M. oryzae. However, the proportions of highly resistant lines and the mean resistance frequency(RF) varied among the four types, with resistance in decreasing order shown by three-line restorer lines, three-line maintainer lines, two-line sterile lines, and two-line restorer lines. All 88 hybrid rice parental lines carried more than one R gene, but none carried the R genes Pi1 and Pi2. Although Pid3 and Pi9 were present only in three-line restorer lines and Pigm only in three-line maintainer lines, the remaining six R genes(Pib, Pid2, Pi5, Pia, Pi54, and Pita) were present in the four types of hybrid rice parent with significantly different distribution frequencies. The correlation between R genes and resistance reactions was investigated. The results are expected to provide useful information for rational utilization of major R genes in hybrid rice breeding programs.
基金funded by the National Key Research and Development Program of China (2016YFD0300103)the earmarked fund for China Agriculture Research System (CARS-02-12)
文摘Over the past seven decades, the grain yield of maize(Zea mays L.) has increased continuously in China, mostly due to hybridization innovations, particularly recent genetic improvements in photosynthesis. In order to reveal photosynthetic characters of elite inbred lines in different ears, a field experiment was conducted at the North China Plain of Shandong Province in China. Six parental lines of maize introduced in three eras(the 1960 s, 1980 s, and 2000 s) were investigated diurnal variation of gas exchange, chlorophyll fluorescence, and photosynthetic response characteristic at the grain filling stage. Compared to earlier parental lines, the 2000 s parental lines always had higher net photosynthetic rate(Pn) throughout the day, especially at noon, and a mid-day depression in Pn did not occur in all hybrids parental lines. Moreover, the stomatal conductance(Gs) and water use efficiency(WUE) of the 2000 s’ lines showed higher value than those of the 1960 s’ and 1980 s’ lines. The inbred lines differences in photosynthetic parameters were partly owing to their different quantum carboxylation efficiencies and light synthase activities. Simultaneously, the 2000 s parental lines exhibited lower light and CO2 compensation points, and their higher apparent quantum yield, and carboxylation efficiency. These suggested that the modern parental lines required lower light intensity and less CO2 to maintain a relatively high photosynthetic capacity, substantially increasing leaf physical quality and stress resistance. It provided crucial information of high photo-efficiency and stress-resistance breeding in maize.
基金Supported by Special Fund for Agro-scientific Research in the Public Interest(201303102)the Agricultural Science Independent Innovation Foundation of Jiangsu Province[CX(12)3042]~~
文摘The amount of root bleeding sap, contents of chlorophyl , nutrients and hormones in flag leaves of a super-hybrid rice cultivar Liangyoupeijiu （LYPJ） and its parents 9311 and Pei’ai 64S after heading were measured in this study. The re-sults revealed that compared with 9311, the chlorophyl content of LYPJ reduced more quickly after heading, and then kept at a lower level, which was an obvious characteristic of premature senescence. The other physiological indices of LYPJ af-ter heading except abscisic acid （ABA） content in leaf and root also maintained at a lower level than 9311, while al the physiological indices of the sterile line Pei＇ai 64S were lower than LYPJ. So it was speculated that the early-aging characteristic of LYPJ may be inherited from Pei’ai 64S. Al the leaf and root early-aging traits reduced for LYPJ and its parent lines after heading, their leaf and root aged grad-ual y, which indicated that the above-ground （leaf） and under-ground （root） parts cor-related to each other closely, but there was not absolute correlations between them judged from the data.
文摘The genetic diversity of 41 parental lines popularized in commercial hybrid rice production in China was studied by using cluster analysis of morphological traits and simple sequence repeat （SSR） markers. Forty-one entries were assigned into two clusters （i.e. early or medium-maturing cluster; medium or late-maturing cluster） and further assigned into six sub-clusters based on morphological trait cluster analysis, The early or medium-maturing cluster was composed of 15 maintainer lines, four early-maturing restorer lines and two thermo-sensitive genic male sterile lines, and the medium or late-maturing cluster included 16 restorer lines and 4 medium or late-maturing maintainer lines. Moreover, the SSR cluster analysis classified 41 entries into two groups （i.e, maintainer line group and restorer line group） and seven sub-groups. The maintainer line group consisted of all 19 maintainer lines, two thermo-sensitive genic male sterile lines, while the restorer line group was composed of all 20 restorer lines. The SSR analysis fitted better with the pedigree information. From the views on hybrid rice breeding, the results suggested that SSR analysis might be a better method to study the diversity of parental lines in indica hybrid rice.
