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Isumi, Japan

Furukawa T.,University of California at Davis | Furukawa T.,Mikado Kyowa Seed Co. | Angelis K.J.,Academy of Sciences of the Czech Republic | Britt A.B.,University of California at Davis
Frontiers in Plant Science

The DNA double-strand break (DSB) is a critical type of damage, and can be induced by both endogenous sources (e.g., errors of oxidative metabolism, transposable elements, programmed meiotic breaks, or perturbation of the DNA replication fork) and exogenous sources (e.g., ionizing radiation or radiomimetic chemicals). Although higher plants, like mammals, are thought to preferentially repair DSBs via nonhomologous end joining (NHEJ), much remains unclear about plant DSB repair pathways. Our reverse genetic approach suggests that DNA polymerase λ is involved in DSB repair in Arabidopsis. The Arabidopsis T-DNA insertion mutant (atpolλ-1) displayed sensitivity to both gamma-irradiation and treatment with radiomimetic reagents, but not to other DNA damaging treatments. The atpolλ-1 mutant showed a moderate sensitivity to DSBs, while Arabidopsis Ku70 and DNA ligase 4 mutants (atku70-3 and atlig4-2), both of which play critical roles in NHEJ, exhibited a hypersensitivity to these treatments. The atpolλ-1/atlig4-2 double mutant exhibited a higher sensitivity to DSBs than each single mutant, but the atku70/atpolλ-1 showed similar sensitivity to the atku70-3 mutant. We showed that transcription of the DNA ligase 1, DNA ligase 6, and Wee1 genes was quickly induced by BLM in several NHEJ deficient mutants in contrast to wild-type. Finally, the T-DNA transformation efficiency dropped in NHEJ deficient mutants and the lowest transformation efficiency was scored in the atpolλ-1/atlig4-2 double mutant. These results imply that AtPolλ is involved in both DSB repair and DNA damage response pathway. © 2015 Furukawa, Angelis and Britt. Source

Shirasawa K.,Kazusa DNA Research Institute | Oyama M.,Mikado Kyowa Seed Co. | Hirakawa H.,Kazusa DNA Research Institute | Sato S.,Kazusa DNA Research Institute | And 13 more authors.
DNA Research

Raphanus sativus (2n 2x 18) is a widely cultivated member of the family Brassicaceae, for which genomic resources are available only to a limited extent in comparison to many other members of the family. To promote more genetic and genomic studies and to enhance breeding programmes of R. sativus, we have prepared genetic resources such as complementary DNA libraries, expressed sequences tags (ESTs), simple sequence repeat (SSR) markers and a genetic linkage map. A total of 26 606 ESTs have been collected from seedlings, roots, leaves, and flowers, and clustered into 10 381 unigenes. Similarities were observed between the expression patterns of transcripts from R. sativus and those from representative members of the genera Arabidopsis and Brassica, indicating their functional relatedness. The EST sequence data were used to design 3800 SSR markers and consequently 630 polymorphic SSR loci and 213 reported marker loci have been mapped onto nine linkage groups, covering 1129.2 cM with an average distance of 1.3 cM between loci. Comparison of the mapped EST-SSR marker positions in R. sativus with the genome sequence of A. thaliana indicated that the Brassicaceae members have evolved from a common ancestor. It appears that genomic fragments corresponding to those of A. thaliana have been doubled and tripled in R. sativus. The genetic map developed here is expected to provide a standard map for the genetics, genomics, and molecular breeding of R. sativus as well as of related species. The resources are available at http://marker.kazusa.or.jp/Daikon. © 2011 The Author. Source

Wako T.,Japan National Agriculture and Food Research Organization | Wako T.,Tottori University | Yamashita K.-I.,Japan National Agriculture and Food Research Organization | Tsukazaki H.,Japan National Agriculture and Food Research Organization | And 10 more authors.

Bunching onion (Allium fistulosum L.; 2n = 16), bulb onion (Allium cepa L. Common onion group), and shallot (Allium cepa L. Aggregatum group) cultivars were inoculated with rust fungus, Puccinia allii, isolated from bunching onion. Bulb onions and shallots are highly resistant to rust, suggesting they would serve as useful resources for breeding rust resistant bunching onions. To identify the A. cepa chromosome(s) related to rust resistance, a complete set of eight A. fistulosum-shallot monosomic alien addition lines (MAALs) were inoculated with P. allii. At the seedling stage, FF+1A showed a high level of resistance in controlled-environment experiments, suggesting that the genes related to rust resistance could be located on shallot chromosome 1A. While MAAL, multi-chromosome addition line, and hypoallotriploid adult plants did not exhibit strong resistance to rust. In contrast to the high resistance of shallot, the addition line FF+1A+5A showed reproducibly high levels of rust resistance. © 2015 Published by NRC Research Press. Source

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