Advances in rice chromosome research, 1995-2000

Observation of the internal ultrastructure of human chromosomes by transmission electron microscopy (TEM) has frequently been attempted in spite of the difficulties in detaching metaphase chromosome spreads from the glass slide for further processing. In this study we have used a method in which metaphase chromosome spreads were prepared on a flexible thermoplastic membrane (ACLAR) film. To assess chromosome identity, a diamidino-phenylindole staining and karyotying was first done using a conventional cytogenetic system. The chromosome spreads were then fixed with 1% osmium tetroxide, stained with freshly prepared 2% tannic acid, dehydrated, and flat-embedded in epoxy resin. The resin sheet was easily detachable and carried whole chromosome spreads. By this method, TEM observation of chromosomes from normal human lymphocytes allowed a thorough examination of the ultrastructure of centromeres, telomeres, fragile sites, and other chromosomal regions. Various ultrastructural patterns including thick electron dense boundaries, less dense internal regions, and extended chromatin loops at the periphery of the chromosomes were discernible. Application of the present method to chromosome research is expected to provide comprehensive information on the internal ultrastructure of different chromosomal regions in relation to function.

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High-Resolution Pachytene Chromosome Mapping of Bacterial Artificial Chromosomes Anchored by Genetic Markers Reveals the Centromere Location and the Distribution of Genetic Recombination Along Chromosome 10 of Rice

Genetics ◽

10.1093/genetics/157.4.1749 ◽

2001 ◽

Vol 157 (4) ◽

pp. 1749-1757 ◽

Cited By ~ 11

Author(s):

Zhukuan Cheng ◽

Gernot G Presting ◽

C Robin Buell ◽

Rod A Wing ◽

Jiming Jiang

Keyword(s):

Large Scale ◽

Genetic Recombination ◽

Physical Map ◽

Rice Chromosome ◽

Resolving Power ◽

Pachytene Chromosome ◽

Chromosome 10 ◽

Bac Clone ◽

Fish Mapping ◽

Artificial Chromosomes

AbstractLarge-scale physical mapping has been a major challenge for plant geneticists due to the lack of techniques that are widely affordable and can be applied to different species. Here we present a physical map of rice chromosome 10 developed by fluorescence in situ hybridization (FISH) mapping of bacterial artificial chromosome (BAC) clones on meiotic pachytene chromosomes. This physical map is fully integrated with a genetic linkage map of rice chromosome 10 because each BAC clone is anchored by a genetically mapped restriction fragment length polymorphism marker. The pachytene chromosome-based FISH mapping shows a superior resolving power compared to the somatic metaphase chromosome-based methods. The telomere-centromere orientation of DNA clones separated by 40 kb can be resolved on early pachytene chromosomes. Genetic recombination is generally evenly distributed along rice chromosome 10. However, the highly heterochromatic short arm shows a lower recombination frequency than the largely euchromatic long arm. Suppression of recombination was found in the centromeric region, but the affected region is far smaller than those reported in wheat and barley. Our FISH mapping effort also revealed the precise genetic position of the centromere on chromosome 10.

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Translocation of a 190-kb mitochondrial fragment into rice chromosome 12 followed by the integration of four retrotransposons

International Journal of Biological Sciences ◽

10.7150/ijbs.1.110 ◽

2005 ◽

pp. 110-113 ◽

Cited By ~ 7

Author(s):

Minoru Ueda ◽

Nobuhiro Tsutsumi ◽

Koh-ichi Kadowaki

Keyword(s):

Rice Chromosome ◽

Chromosome 12 ◽

Mitochondrial Fragment

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Substitution Mapping of Two Closely Linked QTLs Controlling Grain Chalkiness and Grain Shape on Rice Chromosome 8

10.21203/rs.3.rs-511903/v1 ◽

2021 ◽

Author(s):

Weifeng Yang ◽

Liang Xiong ◽

Jiayan Liang ◽

Qingwen Hao ◽

Xin Luan ◽

...

Keyword(s):

Grain Quality ◽

Grain Shape ◽

Rice Chromosome ◽

Chromosome 8 ◽

High Yield ◽

Rice Grain ◽

Rice Varieties ◽

Substitution Mapping ◽

Grain Width ◽

Grain Chalkiness

Abstract Background: Rice varieties are required to have high yield and good grain quality. Grain chalkiness and grain shape are two important traits of rice grain quality. Low chalkiness slender grains are preferred by most rice consumers. Here, we dissected two closely linked quantitative trait loci (QTLs) controlling grain chalkiness and grain shape on rice chromosome 8 by substitution mapping. Results: Two closely linked QTLs controlling grain chalkiness and grain shape were identified using single-segment substitution lines (SSSLs). The two QTLs were then dissected on rice chromosome 8 by secondary substitution mapping. qPGC8.1 was located in an interval of 1382.6 kb and qPGC8.2 was mapped in a 2057.1 kb region. The maximum distance of the two QTLs was 4.37 Mb and the space distance of two QTL intervals was 0.72 Mb. qPGC8.1 controlled grain chalkiness and grain width. qPGC8.2 was responsible for grain chalkiness and for grain length and grain width. The additive effects of qPGC8.1 and qPGC8.2 on grain chalkiness were not affected by heat stress. Conclusions: Two closely linked QTLs qPGC8.1 and qPGC8.2 were dissected on rice chromosome 8. They controlled the phenotypes of grain chalkiness and grain shape. The two QTLs were insensitive to high temperature.

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