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1.
Summary Recurrent backcrossing has been carried out with a view to transfer a gene for non-glutinous endosperm from two strains of O. glaberrima (Wx g /Wx g ) to glutinous japonica and indica varieties (wx/wx) of Oryza sativa. In the course of backcrosses Wx g /wx segregants were crossed with each of the two glutinous varieties of sativa as the respective recurrent male parent. The wx/wx and Wx g /wx segregants in the successive generations were consistently fully fertile and semi-sterile, respectively. The semi-sterility of Wx g /wx plants was attributable to abortion of most of the pollen grains carrying the gene wx. The nucleus but not cytoplasm was related to the semi-sterility. The Wx g /Wx plants having the gene for non-glutinous endosperm of a glaberrima strain and a japonica variety of sativa were also semi-sterile. Both wx- and Wx-megaspores in the plants heterozygous for the gene Wx g were deleteriously affected. The results could be explained by assuming that a factor tightly linked with the gene Wx g of glaberrima sterilizes gametes not carrying it in the heterozygotes and that the gametocidal action is exerted when combined with the sativa nucleus by the recurrent backcross method.  相似文献   

2.
The Wx b gene, one of the alleles at the rice waxy(wx) locus, is activated at cool temperatures during seed development, andas a result, a large amount of amylose is accumulated causing a reductionin rice grain quality. We found that the seeds of a du mutant couldbe visibly distinguished depending on whether they matured at cool ornormal temperatures. Using these characteristics, we isolated a mutantcandidate insensitive to cool temperatures. While the amylose content inthe original line was about 2% at a normal temperature (28 °C)and 12% at a cool temperature (21 °C), in the mutant candidate(coi) the amylose content was not affected by temperatures, i.e. theamylose content was about 3% at both temperatures. This finding incombination with the results of an immunoblot analysis indicated that theabsence of an increase in the amylose content in this mutant was caused bya constant level of Wx gene expression at normal and cooltemperature. Genetic analysis revealed that this insensitivity to cooltemperatures was caused by a single recessive mutation. This mutantshould be useful in breeding programs designed to produce rice of desiredquality at cool temperatures and in understanding genetic and molecularmechanisms that respond to slight changes in temperature.  相似文献   

3.
Hybrids between indica and japonica rice varieties usually show partial sterility, and are a major limiting factor in the utilization of heterosis at subspecific level. When studying male-gamete (pollen) abortion, a possibly important cause for sterility, six loci (S-a, S-b, S-c, S-d, S-e and S-f) for F1 pollen sterility were identified. Here we report genetic and linkage analysis of S-c locus using molecular markers in a cross between Taichung 65, a japonica variety carrying allele S-c j, and its isogenic line TISL5, carrying alleleS-c j. Our results show that pollen sterility occurring in the hybrids is controlled by one locus. We used 208 RFLP markers, as well as 500 RAPD primers, to survey the polymorphism between Taichung 65 and TISL5. Six RFLP markers located on a small region of chromosome 3, detected different RFLP patterns. Co-segregation analysis of fertility and RFLP patterns with 123 F2 plants confirmed that the markers RG227, RG391, R1420 were completely linked with the S-c locus. The genetic distances between the markers C730, RG166 and RG369 and the S-c locus were 0.5 cM, 3.4 cM, and 3.4 cM respectively. Distorted F2 ratios were also observed for these 4 RFLP markers in the cross. This result suggests that the `one locus sporo-gametophytic' model could explain F1 hybrid pollen sterility in cultivated rice. RG227, the completely linked marker, has been converted to STS marker for marker-assisted selection. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

4.
The agronomic and morphological characteristics of Agrobacterium-transformed rice plants carrying the synthetic cry1Ab or cry1Ac gene were investigated. Tremendous variations in plant height, seed fertility, grain size and other traits were seen in 80 T1 lines, derived from 80 T0 plants of 9 rice varieties. On average, about 33% T1 lines had either morphological or agronomic variant plants. Most of the variations in T1 plants had no significant correlation with transgene insertion and were proved heritable to their progenies. Genetic analysis in T3 or T4 generations showed some simple mutations such as chlorophyll deficiency and stunted plants were independent of transgene insertion and seemed to be controlled by a pair of single genes. However, in two independent transgenic progenies of Xiushui 11, all plants homozygous for transgenes showed dwarfism while all hemizygous and null segregants had normal plant heights. Two advanced homozygous Bt lines, KMD1 and KMD2, were developed from these two progenies. Comparison of the agronomic traits of KMD1 and KMD2 with their parent displayed marked differences among them in terms of seedling growth, tillering ability, yield components and yield potential. The genetic variation observed was generally not linked to the transgene locus and was ascribed to somaclonal variation, but other causes might also exist in particular cases. The results are discussed in the context of choosing appropriate transformation methodology for rice breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

5.
This study was to determine the agronomic and genetic characteristics of a novel rice dominant dwarf mutant 986083D (japonica) and its potential in breeding. 986083D derived from the anther culture of an autotetraploid indica/japonica hybrid and its progeny segregated into normal and dwarf plants. Homozygous and heterozygous 986083D plants looked similar phenotypically, showing shortened stature, erect leaves, more tillers and poor fertility. The segregation ratio of dwarf to normal plants fit the expected 3:1 by χ2-test in 77 out of 88 tested lines. Crosses between homozygous 986083D and eight other rice varieties had uniform semi-dwarf F1 plants. The F1 plants from crosses between heterozygous 986083D and five other varieties had normal and semi-dwarf plants close to the expected ratio of 1:1. The reduction of plant height in F1 plants ranged from 40.0 to 53.5% in a subtropical environment and from 37.5 to 48.2% in a temperate environment. 986083D showed moderate sensitivity to exogenously applied GA3 in terms of elongation of shoots and induction of α-amylase activity in the endosperm. Linkage analysis showed that the dominant dwarf gene (designated as Dx) in 986083D was not allelic to D53. Dx was roughly mapped to the short arm of chromosome 8. All results showed that 986083D was a novel mutant controlled by single dominant gene, providing a valuable material in rice breeding. Ruizhen Qin, Yang Qiu contributed equally to this work.  相似文献   

6.
Summary In a comparison of methods to study inheritance of plant elongation ability, 15-, 20-, 25-, 30-, and 35-day-old F2 populations of a cross between Baisbish (floating variety) and IR42 (nonelongating semidwarf modern variety) of rice, (Oryza sativa L.) were subjected to 65 cm water depth for 7 days. Frequency distribution of plant height before and after submergence was obtained. Bimodal curves in 15-, 20- and 25-day-old populations gave good fits to 9:7 elongating: nonelongating plants, suggesting that elongation was due to two dominant complementary genes. Segregation in the 30-day-old population was not clear-cut. A seedling age of 20 days was subsequently chosen for further studies.Two F2's involving floating rice and a nonelongating semidwarf; four F2's involving floating rice and an elongating semidwarf; and two F2's involving elongating and nonelongating semidwarf parents were studied with 20-day-old seedlings in the same way. Floating rice combinations with nonelongating semidwarf parents as well as with elongating semidwarf parents segregated into 9:7 elongating: nonelongating ratio. It is possible that because elongating and nonelongating dwarf parents did not differ much in elongation ability at seedling age, their combination with floating rice parents provided similar segregation. The F2 distributions for height in elongating and nonelongating dwarf cross combinations were continuous with one peak.Genetic constitution of parents proposed are Sd1 Sd1 El El for floating parents, sd1 sd1 El El for semidwarf elongating, and sd1 sd1 el el for dwarf nonelongating.  相似文献   

7.
Mark J. Bassett 《Euphytica》2005,141(1-2):139-145
The inheritance of the virgata pattern of partly colored seed coats found in common bean (Phaseolus vulgaris L.) Early Giant (EG) was studied by a series of test crosses with line 5-593 and genetic stocks developed by backcrossing selected genes into the recurrent parent 5-593, a Florida dry bean breeding line with a self-colored, black seed coat with genotype T Z Bip P [C r] J G B V Rk. Analysis of the F2 from the cross EG × 5-593 led to the hypothesis that the virgata pattern of EG has genotype t z bipvgt, where vgt stands for virgata. The test cross EG × t z virgarcus BC3 5-593 confirmed the hypothesis that EG carries t z from data recorded in F1, F2, and 27 F3 progenies from randomly selected F2 plants. The F3 segregation was also consistent with the hypothesis that a single recessive gene converts virgarcus into virgata. The test cross EG × t z bip bipunctata BC3 5-593 failed to show genetic complementation in F1 progeny, and the F2 segregated 3:1 for the parental phenotypes virgata and bipunctata, respectively. Including previously published data, all possible crosses were made among bipunctata, virgata, and virgarcus parents, supporting a multiple allelic series at Bip. We propose the gene symbol bipvgt for the new allele at Bip, where the allelic series has the order of gene dominance Bip > bipvgt > bip. Based on test crosses, the complete seed-coat color and pattern genotype of EG is tz bipvgt P [C r] J G B vlae rkd.  相似文献   

8.
Summary Some photosynthetic characters as-leaf anatomy, leaf photosynthetic rate and CO2 compensation pointdistinguishing C3 and C4 plants and physiological characters as leaf area ratio, nitrogen content, leaf stem ratio and total shoot-to-root and deep root-to-shoot ratios have been studied in rice × sorghum and rice × wheat hybrids. Rice × sorghum 1. has lower values of photosynthetic rate, leaf nitrogen, total root and deep root-to-shoot ratio and CO2 compensation point as of rice parent where as, rice × sorghym 2. is superior in all these characters. Both hybrids lack kranz anatomy. Though both rice × sorghum hybrids show characters of C3 rice plant but rice × sorghum 2. has improved drought tolerance and leaf characters in relation to yield. Rice × wheat hybrid have higher assimilatory area and higher total root-to-shoot ratio. Grains of rice × wheat hybrids are identical to rice grain. However, as grains of rice × wheat hybrid does not contain seed coat, it could be exploited as novel rice germplasm after improvement.Abbreviations T CO2 compensation point - T21 CO2 compensation point at 21% O2 - T2 CO2 compensation point at 2% O2 - dR/sR deep Root-to-shoot Ratio - LAR Leaf Area Ratio - CER photosynthetic rate - TR/SR Total Root-to-Shoot Ratio  相似文献   

9.
S. Y. Lin  H. Ikehashi 《Euphytica》1993,67(1-2):35-40
Summary A locus for male gamete abortion in hybrids for Japonica and Indica rice was identified with the aid of marker genes Rc and Est-9 on chromosome 7. In an Indica-Japonica cross, AKAMAI 1/IR50, the Indica allele Est-9 2 was transmitted via the male gamete with a ratio of 0.29 instead of the normal 0.5, whereas no segregation distortion was observed for the Rc locus. The recombination value (p) for Est-9 and Rc was estimated to be 0.38 by a least square method after adjusting Mendelian segregation ratios with the male transmission ratios of 0.29 (Tr) for Est-9 2 and 0.71 (1-Tr) for Est-9 1. The recombination value (q) for the new locus for male gamete abortion, ga-11, and Est-9 was estimated to be 0.23 by using 56 F3 lines from F2 plants which were heterozygous for the Est-9 locus. No linkage for Rc and ga-11 was found. Therefore, the two markers and ga-11 were located in the order of ga-11-Est-9-Rc. Using the estimated recombination value (q), the male transmission rate (k) of ga-11 a was estimated to be 0.11 with the F2 data and-0.07 with the F3 line data. Thus, it was apparent that male gametes possessing ga-11 a were frequently aborted in the Indica-Japonica hybrid.  相似文献   

10.
B. Y. Chen  W. K. Heneen 《Euphytica》1992,59(2-3):157-163
Summary Seed colour inheritance was studied in five yellow-seeded and one black-seeded B. campestris accessions. Diallel crosses between the yellow-seeded types indicated that the four var. yellow sarson accessions of Indian origin had the same genotype for seed colour but were different from the Swedish yellow-seeded breeding line. Black seed colour was dominant over yellow. The segregation patterns for seed colour in F2 (Including reciprocals) and BC1 (backcross of F1 to the yellow-seeded parent) indicated that the black seed colour was conditioned by a single dominant gene. Seed colour was mainly controlled by the maternal genotype but influenced by the interplay between the maternal and endosperm and/or embryonic genotypes. For developing yellow-seeded B. napus genotypes, resynthesized B. napus lines containing genes for yellow seed (Chen et al., 1988) were crossed with B. napus of yellow/brown seeds, or with yellow-seeded B. carinata. Yellow-seeded F2 plants were found in the crosses that involved the B. napus breeding line. However, this yellow-seeded character did not breed true up to F4. Crosses between a yellow-seeded F3 plant and a monogenomically controlled black-seeded B. napus line of resynthesized origin revealed that the black-seeded trait in the B. alboglabra genome was possibly governed by two independently dominant genes with duplicated effect. Crossability between the resynthesized B. napus lines as female and B. carinata as male was fairly high. The sterility of the F1 plants prevented further breeding progress for developing yellow-seeded B. napus by this strategy.  相似文献   

11.
Summary In the synthesis of primary hexaploid triticale, a cross-incompatibility barrier exists when tetraploid wheat (4X) is crossed with diploid (2X) rye. Fertilization may occur, however, abnormal endosperm development usually leads to premature embryo death. Four selected tetraploid wheat lines were crossed as females with seven open-pollinated rye lines and the resulting embryos were rescued in vitro 13–16 days after pollination. The wheat genotypes showed a major influence on crossability (seed set), embryo development and plant recovery. The highest efficiency of amphihaploid plant recovery (18.3 plants per 100 pollinated florets) was obtained from one 4X wheat line originally selected from the cross T. carthlicum × T. dicoccoides. Some of the 3X amphihaploid plants (ABR) derived from two wheat lines showed relatively high level of partial fertility presumably as a result of meiotic restitution. Correlation analysis showed that crossability (seed set), normal hybrid embryo development in vivo and embryo culturability were independent of each other.  相似文献   

12.
The African rice Oryza glaberrima, traditionally cultivated since more than 3.500 years, is of poor agronomic performance but resistant/tolerant to various stresses and diseases. The introduction of these characters into O. sativa cultivars is difficult since crossing barriers cause spikelet sterility in F1. Backcrossing can restore fertility and recently facilitated the development of fertile O. glaberrima × O. sativa ssp. japonica hybrid progenies for rain fed systems. With the objective to gain access to African rice germplasm for improvement of irrigated rice, crosses were performed with eighteen O. glaberrima and twenty O. sativa ssp. indica accessions. In total about one hundred F1-hybrid grains were obtained. The F1 plants were all completely sterile and backcrossing (BC) to O. sativa was performed in order to restore spikelet fertility. Monitoring of Tog5681 × IR64 hybrid progenies under field conditions revealed a broad genetic diversity within the BC1 and BC2 populations. Some BC1 and BC2 progeny plants outperformed the O. sativa parent, indicating that the heterozygocity level and complementary gene action after two backcrosses are still sufficient to positively influence plant vigor. Spikelet fertility of progenies was highly variable, but almost complete fertility was already observed within the BC1F2 population. High spikelet fertility was preserved in one out of two analyzed BC1F3 families and inmost of the BC2F3 families. The ability to restore spikelet fertility within few generations and the potential of the genetic diversity present in interspecific progenies facilitates the development of plant types specifically designed for the African irrigated and lowland environment. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

13.
Summary As S-specific glycoproteins react with concanavalin A (ConA), they could be stained sensitively with ConA-FITC after cellulose acetate isoelectric focusing of stigma proteins in self-incompatible crucifers. By this method the S genotype of an individual plant could be inferred within 4 h using 4 flowers. This simple and rapid method may be applicable for describing S genotypes in practical F1 breeding.  相似文献   

14.
M. Kato  S. Tokumasu 《Euphytica》1976,25(1):761-767
Summary In Brassicoraphanus (amphidiploids between Brassica japonica Sieb. and Raphanus sativus L.), yellow-flowered plants that occurred among originally white-flowered plants showed an increased seed fertility. It is assumed that the gene Y (yellow-flower gene) from Brassica and the gene W (white-flower gene) from Raphanus are located at corresponding loci of only partially homologous chromosomes. W is dominant (epistatic) over Y. The normal white-flowered plants have the genotype YYWW. A YYYW-plant was found, which is assumed to have arisen through crossing-over following multivalent formation. In the progeny of this plant, yellow-flowered plants (YYYY) as well as white-flowered plants (YYWW, YYYW) appeared. The gene for flower colour is closely linked to a gene which controls the development of embryos (or endosperm). This gene promotes the development of embryos in homozygous condition. Therefore, the embryo having only the yellow-flower gene can develop more easily into viable seed than the embryo having the white-flower gene. It is also possible that the sterility of white-flowered plants is caused by a discordance between the cytoplasm of Brassica and W (or genes linked to W) of Raphanus.  相似文献   

15.
The amount of long chains (LC) of amylopectin in high-amylose rice is thought to be one of the important determinants of its quality when cooked. A wide range of differences in LC content have been reported in rice varieties, which can be clearly divided into four classes based on LC and apparent amylose content: namely, amylose and LC-free, low or medium-amylose and low-LC, high-amylose and medium-LC, high-amylose and high-LC. However, genetic factors controlling LC content have not been fully understood. Here, we performed quantitative trait loci (QTL) analysis of LC content using 157 recombinant inbred lines (RILs) derived from a cross of a low-LC cultivar, Hyogokitanishiki, and a high-LC line, Hokuriku 142. By analyzing randomly selected 15 RILs, it was shown that high LC content (≥11%) was associated with high setback viscosity (≥200 RVU), and that low LC (≤ 3%) was associated with low setback viscosity (≤ 130 RVU), as measured by a Rapid Visco Analyzer. With setback viscosity as an indicator for LC content, QTL analysis was conducted using 60 DNA markers including a CAPS marker that distinguished Wx a and Wx b alleles coding for granule-bound starch synthase I (GBSSI or Wx protein), the enzyme working for amylose biosynthesis. Only one QTL with a peak log of likelihood score at the wx locus was detected, and no line showing setback viscosity corresponding to the medium-LC class appeared. The fact that wx mutants of Hokuriku 142 lacked LC in their rice starch supports the view that the functional Wx allele is indispensable for LC synthesis in addition to amylose synthesis in rice endosperm. We suggest three possible reasons why no line with medium-LC content was observed. First, the locus (loci) responsible for generation of medium-LC may be located very close to the wx locus and not able to be dissected by the population and DNA markers we used. Second, there may be special QTLs for medium-LC cultivars that do not exist in low- or high-LC cultivars. Third, medium-LC cultivars may have an as-yet unidentified Wx allele with lower capability in LC synthesis compared to the Wx allele in high-LC cultivars.  相似文献   

16.
Yoshio Sano 《Euphytica》1985,34(3):587-592
Summary To study differential nucleus-cytoplasm interactions between the two cultivated rice species, Oryza sativa and O. glaberrima, cytoplasmic substitution lines were made by using a glaberrima strain (G) and an Indica strain of sativa (S). The G cytoplasm had no adverse effect on pollen development when combined with the nucleus of S. On the other hand, when the S cytoplasm was combined with the G nucleus, the substitution line showed no seed set because of male sterility although the pollen grains were normally stained with I2-KI solution. A dominant gene derived from S strain seemed to cause anther indehiscence in the substitution line. Further, a restorer gene (Rf j)from Akebono of Japonica type was effective on pollen restoration in the male sterile line, suggesting that the S cytoplasm is the same as those of Japonica type in terms of a fertility-restoring system.This paper is Genetic studies of speciation in cultivated rice. 4.  相似文献   

17.
Summary Hybrids between T. ambiguum and T. repens were successfully established after ovule culture. The hybrids were male sterile but one of the hybrids produced a single seed when backcrossed to T. repens, while the other produced a significantly greater number of seeds. The majority of the backcross hybrids from the latter had 48 chromosomes, being produced from the fertilisation of unreduced gametes of the F1 hybrid by T. repens pollen. Regular meiosis in the BC1 hybrid resulted in the production of balanced gametes containing the full complement of T. repens chromosomes and the polyhaploid set of T. ambiguum chromosomes. There was no difficulty in establishing a substantial population of BC2 hybrids. The meiotic behaviour of the BC1 hybrid indicated that it should be possible to transfer genes from T. ambiguum into white clover T. repens. The significance of the results in terms of the use of alien variation in the improvement of white clover is discussed.  相似文献   

18.
Zhang  Xiao-ming  Shi  Chun-hai  Yue  Shen-Hai  Wu  Jian-guo  Bao  Geng-liang 《Euphytica》2004,139(3):249-256
Genetics of methionine content in indica-japonica hybrid rice (Oryza sativa L.) was studied in 35 F1 hybrids derived from crossing 7 male-sterile indica rice cultivars with 5 restorer japonica rice cultivars. Two genetic models and their corresponding statistical methods for quantitative traits of triploid endosperm in cereal crops were used for the analysis. One is the unconditional model, which refers to the analysis of cumulative measurements along the developmental stages, while another is the conditional model, which relates to analysis throughout the developmental stages. Results showed that methionine content of indica-japonica hybrid rice was controlled by expression of triploid endosperm nuclear genes, cytoplasm genes, diploid maternal plant nuclear genes, and their genotype-environment interaction effects. Dominant effects were important at the first three developmental stages, while additive effects were important at the next two stages of grain development under both unconditional and conditional analyses. With regard to the components of heritability, maternal and cytoplasm general heritabilities and their environmental interaction heritabilities were important. It was suggested that enhancing methionine content could be more efficient when selection is based on maternal plants in early breeding generations.  相似文献   

19.
Endosperm balance number (EBN) was used to predict the outcome of crosses among a series of complex polyploid interspecific hybrids between Trifolium repens and T. nigrescens. Normal endosperm development, and hence seed‐set, requires a 2 : 1 maternal : paternal EBN ratio in endosperm. Based on their crossability, T. repens (2n = 4x = 32) and T. nigrescens (2n = 2x = 16) were assigned the same EBN of 4. This number was used to predict the relative success of different backcrosses and intercrosses. The method was further developed to successfully predict which gametes would effect fertilization when complex polyploid hybrids with uneven genomic constitutions (5x, 7x) produced mixtures of euploid and aneuploid gametes. This was achieved by allocating EBNs to all potential gametes of complex polyploids. Allocation of gamete EBNs enabled not only prediction of the success or failure of a cross, but also which gametes would be filtered to effect fertilization in complex crosses. This enhanced ability to understand the potential outcomes of complex crosses will increase the efficiency of plant breeding programmes that integrate secondary gene‐pools into economic species by interspecific hybridization.  相似文献   

20.
M. Dujardin  W. W. Hanna 《Euphytica》1989,42(3):285-289
Summary Autotetraploid (2n=4x=28) pearl millet inbred lines, Tift 23BE and Tift 239DB, have been developed for use in crosses with other polyploid Pennisetum species. Each line set less than 1% and 3% selfed and open-pollinated seed, respectively. Seed germination was usually less than 17%. First generation (F1) hybrids between the two inbreds set up to 61% seed while up to 40% of the seed from hybrids germinated.Seed weight per inflorescence for two planting dates averaged 0.32 g and 3.06 g for the two inbreds and the second generation F2 progeny, respectively. One hundred seed weight was also significantly higher (0.78 g vs 0.48 g) in the F2 progeny, probably due better endosperm development. Chromosome behavior and pollen stainability were similar in the inbred parents and hybrids. However, the hybrids shed more pollen than the inbred parents.Heterosis was evident in the F1 hybrids and F2 progeny which showed significant increases in plant height, leaf length, leaf width, and inflorescence length in addition to fertility improvement.  相似文献   

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