Breeding Science
Online ISSN : 1347-3735
Print ISSN : 1344-7610
ISSN-L : 1344-7610
Volume 62 , Issue 3
Showing 1-11 articles out of 11 articles from the selected issue
Research Papers
  • Fátima Bosetti, Camila Montebelli, Ana Dionísia L.C. Nov ...
    2012 Volume 62 Issue 3 Pages 209-215
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Low temperatures at the initial stages of rice development prevent fast germination and seedling establishment and may cause significant productivity losses. In order to develop rice cultivars exhibiting cold tolerance, it is necessary to investigate genetic resources, providing basic knowledge to allow the introduction of genes involved in low temperature germination ability from accessions into elite cultivars. Japanese rice accessions were evaluated at the germination under two conditions: 13°C for 28 days (cold stress) and 28°C for seven days (optimal temperature). The traits studied were coleoptile and radicle length under optimal temperature, coleoptile and radicle length under cold and percentage of the reduction in coleptile and radicle length due to low temperature. Among the accessions studied, genetic variation for traits related to germination under low temperatures was observed and accessions exhibiting adequate performance for all investigated traits were identified. The use of multivariate analysis allowed the identification of the genotypes displaying cold tolerance by smaller reductions in coleoptile and radicle lenght in the presence of cold and high vigour, by higher coleoptile and radicle growth under cold.
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  • Khandakar M. Iftekharuddaula, Muhammad A. Salam, Muhammad A. Newaz, He ...
    2012 Volume 62 Issue 3 Pages 216-222
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Marker assisted backcrossing has been used effectively to transfer the submergence tolerance gene SUB1 into popular rice varieties, but the approach can be costly. The selection strategy comprising foreground marker and phenotypic selection was investigated as an alternative. The non-significant correlation coefficients between ranking of phenotypic selection and ranking of background marker selection in BC2F1, BC3F1 and BC3F2 generations indicated inefficiency of phenotypic selection compared to marker-assisted background selection with respect to recovery of the recipient genome. In addition, the introgression size of the chromosome fragment containing SUB1 was approximately 17 Mb, showing the effects of linkage drag. The significant correlation coefficient between rankings of phenotypic selection with the percentage of recipient alleles in the BC1F1 generation suggested that background selection could be avoided in this generation to minimize the genotyping cost. The phenotypically selected best plant of the BC3F1 generation was selfed and backcross recombinant lines were selected in the resulting BC3F4 generation. The selection strategy could be appropriate for the introgression of SUB1 QTL in countries that lack access to high-throughput genotyping facilities.
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  • Kiyosumi Hori, Tomomori Kataoka, Kiyoyuki Miura, Masayuki Yamaguchi, N ...
    2012 Volume 62 Issue 3 Pages 223-234
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Supplementary material
    To identify quantitative trait loci (QTLs) associated with the primary target traits for selection in practical rice breeding programs, backcross inbred lines (BILs) derived from crosses between temperate japonica rice cultivars Nipponbare and Koshihikari were evaluated for 50 agronomic traits at six experimental fields located throughout Japan. Thirty-three of the 50 traits were significantly correlated with heading date. Using a linkage map including 647 single-nucleotide polymorphisms (SNPs), a total of 122 QTLs for 38 traits were mapped on all rice chromosomes except chromosomes 5 and 9. Fifty-eight of the 122 QTLs were detected near the heading date QTLs Hd16 and Hd17 and the remaining 64 QTLs were found in other chromosome regions. QTL analysis of 51 BILs having homozygous for the Koshihikari chromosome segments around Hd16 and Hd17 allowed us to detect 40 QTLs associated with 27 traits; 23 of these QTLs had not been detected in the original analysis. Among the 97 QTLs for the 30 traits measured in multiple environments, the genotype-by-environment interaction was significant for 44 QTLs and not significant for 53 QTLs. These results led us to propose a new selection strategy to improve agronomic performance in temperate japonica rice cultivars.
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  • Carlos A. Sala, Mariano Bulos, Emiliano Altieri, María Laura Ra ...
    2012 Volume 62 Issue 3 Pages 235-240
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Imisun and CLPlus are two imidazolinone tolerance traits in sunflower (Helianthus annuus L.) determined by the expression of two alleles at the locus Ahasl1. Both traits differed in their tolerance level to imazapyr —a type of imidazolinone herbicide— when aboveground biomass is considered, but the concomitant herbicide effect over the root system has not been reported. The objective of this work was to quantify the root biomass response to increased doses of imazapyr in susceptible (ahasl1/ahasl1), Imisun (Ahasl1-1/Ahasl1-1) and CLPlus (Ahasl1-3/Ahasl1-3) homozygous sunflower genotypes. These materials were sprayed at the V2–V4 stage with increased doses of imazapyr (from 0 to 480 g active ingredient ha-1) and 14 days after treatment root biomass of each plant was assessed. Genotype at the Ahasl1 locus, dose of imazapyr and their interaction significantly contributed (P < 0.001) to explain the reduction in root biomass accumulation after herbicide application. Estimated dose of imazapyr required to reduce root biomass accumulation by fifty percent (GR50) differed statistically for the three genotypes under study (P < 0.001). CLPlus genotypes showed the highest values of GR50, 300 times higher on average than the susceptible genotypes, and almost 8 times higher than Imisun materials, demonstrating that both alleles differ in their root biomass response to foliar application of increased doses of imazapyr.
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  • Mitsuyuki Tomiyoshi, Yasuo Yasui, Takanori Ohsako, Cheng-Yun Li, Ohmi ...
    2012 Volume 62 Issue 3 Pages 241-247
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Fagopyrum homotropicum Ohnishi is a self-pollinating wild buckwheat species indigenous to eastern Tibet and the Yunnan and Sichuan Provinces of China. It is useful breeding material for shifting cultivated buckwheat (F. esculentum ssp. esculentum Moench) from out-crossing to self-pollinating. Despite its importance as a genetic resource in buckwheat breeding, the genetic variation of F. homotropicum is poorly understood. In this study, we investigated the genetic variation and phylogenetic relationships of the diploid and tetraploid forms of F. homotropicum based on the nucleotide sequences of a nuclear gene, AGAMOUS (AG). Neighbor-joining analysis revealed that representative individuals clustered into three large groups (Group I, II and III). Each group contained diploid and tetraploid forms of F. homotropicum. We identified tetraploid plants that had two diverged AG sequences; one belonging to Group I and the other belonging to Group II, or one belonging to Group II and the other belonging to Group III. These results suggest that the tetraploid form originated from at least two hybridization events between deeply differentiated diploids. The results also imply that the genetic diversity contributed by tetraploidization of differentiated diploids may have allowed the distribution range of F. homotropicum to expand to the northern areas of China.
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  • Shuri Kato, Asako Matsumoto, Kensuke Yoshimura, Toshio Katsuki, Kojiro ...
    2012 Volume 62 Issue 3 Pages 248-255
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Supplementary material
    Numerous cultivars of Japanese flowering cherry (Prunus subgenus Cerasus) are recognized, but in many cases they are difficult to distinguish morphologically. Therefore, we evaluated the clonal status of 215 designated cultivars using 17 SSR markers. More than half the cultivars were morphologically distinct and had unique genotypes. However, 22 cultivars were found to consist of multiple clones, which probably originate from the chance seedlings, suggesting that their unique characteristics have not been maintained through propagation by grafting alone. We also identified 23 groups consisting of two or more cultivars with identical genotypes. Most members of these groups were putatively synonymously related and morphologically identical. However, some of them were probably derived from bud sport mutants and had distinct morphologies. SSR marker analysis provided useful insights into the clonal status of the examined Japanese flowering cherry cultivars and proved to be a useful tool for cultivar characterization.
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  • Phuong Dang Thai Phan, Hiroki Kageyama, Ryo Ishikawa, Takashige Ishii
    2012 Volume 62 Issue 3 Pages 256-262
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    The Asian wild rice, Oryza rufipogon, has partial outcrossing behavior and shows high levels of genetic variation. To estimate an accurate outcrossing rate of annual form of O. rufipogon, two backcross lines (Lines R1 and R2) between Oryza sativa Nipponbare and O. rufipogon W630 were examined under field conditions. A chromosome survey confirmed that these lines had wild chromosomal segments at more than 92% of marker loci. As for the traits of glume, stamen and pistil, Line R1 showed similar floral morphology as that of O. rufipogon W630, whereas Line R2 had larger glumes. In 2005, 2006 and 2008, a total of 22 backcross plants were planted in the middle of wild rice plots. The successive progenies of each plant were examined using microsatellite markers that could clearly detect self-pollination and outcrossing. The outcrossing rates of Line R1 plants ranged from 4.04% to 25.50% with an average of 10.20%. This indicates that cross-pollination of wild rice is a chance event affected by many environmental factors. The outcrossing rates of Line R2 plants also varied, however, no significant difference was observed between the averages of Lines R1 and R2, suggesting that the glume sizes are not critical for outcrossing ability.
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  • Fumiya Taniguchi, Kazumi Furukawa, Sakura Ota-Metoku, Nobuo Yamaguchi, ...
    2012 Volume 62 Issue 3 Pages 263-273
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Supplementary material
    A few linkage maps of tea have been constructed using pseudo-testcross theory based on dominant marker systems. However, dominant markers are not suitable as landmark markers across a wide range of materials. Therefore, we developed co-dominant SSR markers from genomic DNA and ESTs and constructed a reference map using these co-dominant markers as landmarks. A population of 54 F1 clones derived from reciprocal crosses between ‘Sayamakaori’ and ‘Kana-Ck17’ was used for the linkage analysis. Maps of both parents were constructed from the F1 population that was taken for BC1 population. The order of most of the dominant markers in the parental maps was consistent. We constructed a core map by merging the linkage data for markers that detected polymorphisms in both parents. The core map contains 15 linkage groups, which corresponds to the basic chromosome number of tea. The total length of the core map is 1218 cM. Here, we present the reference map as a central core map sandwiched between the parental maps for each linkage group; the combined maps contain 441 SSRs, 7 CAPS, 2 STS and 674 RAPDs. This newly constructed linkage map can be used as a basic reference linkage map of tea.
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  • Mai Tsuda, Ayako Okuzaki, Yukio Kaneko, Yutaka Tabei
    2012 Volume 62 Issue 3 Pages 274-281
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Several imported transgenic canola (Brassica napus) seeds have been spilled and have grown along roadsides around import ports. B. juncea, a relative of B. napus with which it has high interspecific crossability, is widely distributed throughout Japan. There is public concern about the harmful impacts of feral B. napus plants on biodiversity, but spontaneous hybridization between spilled B. napus and weedy B. juncea populations is hardly revealed. We evaluated the relationship between the hybridization frequency of B. juncea × B. napus and their planting distance in field experiments using the mutagenic herbicide-tolerant B. napus cv. Bn0861 as a pollen source for hybrid screening. The recipient B. juncea cv. Kikarashina was planted in an experimental field with Bn0861 planted in the center. No hybrids were detected under natural flowering conditions in 2009. However, the flowering period was artificially kept overlapping in 2010, leading to a hybridization frequency of 1.62% in the mixed planting area. The hybridization frequency decreased drastically with distance from the pollen source, and was lower under field conditions than estimated from the high crossability, implying that spontaneous hybridization between spilled B. napus and weedy B. juncea is unlikely in the natural environment.
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Notes
  • Takeyuki Kato, Katsunori Hatakeyama, Nobuko Fukino, Satoru Matsumoto
    2012 Volume 62 Issue 3 Pages 282-287
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    In Chinese cabbage (Brassica rapa), the clubroot resistance (CR) genes Crr1 and Crr2 are effective against the mild Plasmodiophora brassicae isolate Ano-01 and the more virulent isolate Wakayama-01, but not against isolate No. 14, classified into pathotype group 3. ‘Akiriso’, a clubroot-resistant F1 cultivar, showed resistance to isolate No. 14. To increase the durability of resistance, we attempted to identify the CR locus in ‘Akiriso’. CR in ‘Akiriso’ segregated as a single dominant gene and was linked to several molecular markers that were also linked to CRb, a CR locus from cultivar ‘CR Shinki’. We developed additional markers around CRb and constructed partial genetic maps of this region in ‘Akiriso’ and ‘CR Shinki’. The positions and order of markers in the genetic maps of the two cultivars were very similar. The segregation ratios for resistance to isolate No. 14 in F2 populations derived from each of the two cultivars were also very similar. These results suggest that the CR locus in ‘Akiriso’ is CRb or a tightly linked locus. The newly developed markers in this study were more closely linked to CRb than previously reported markers and will be useful for marker-assisted selection of CRb in Chinese cabbage breeding.
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  • Rongfeng Hu, Jiehua Wang, Yan Ji, Yingjin Song, Shaohui Yang
    2012 Volume 62 Issue 3 Pages 288-291
    Published: 2012
    Released: November 01, 2012
    JOURNALS FREE ACCESS
    Four highly inducible genes of poplar trees, PtdKTI5, PtdWIN4, PtdPOP3 from hybrid poplar (Populus trichocarpa × P. deltoides) and PtKTI2 from trembling aspen (Populus tremuloides Michx.) have been individually transformed into Arabidopsis thaliana for overexpression. High transcriptional level of each transgene in transgenic Arabidopsis lines was confirmed by RT-PCR analysis. The development, body weight and survivorship of cotton bollworm (Helicoverpa armigera) fed on four types of transgenic Arabidopis plants were evaluated in the laboratory. Our data indicated that these four Populus defense-related genes exhibited various degree of insectital activity on larval and postlarval development of cotton bollworm and may be utilized for herbivore resistance improvement in plant genetic engineering.
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