title: Detection of QTLs for cold tolerance of rice cultivar 'Kuchum' and effect of QTL pyramiding.
abstract: A QTL for cold tolerance at the booting stage of rice cultivar 'Kuchum' was detected and delimited into a 1.36 Mb region, and a cold-tolerant line was developed by QTL pyramiding. Low temperature in summer causes pollen sterility in rice, resulting in a serious loss of yield. The second most widely grown rice cultivar in Japan, 'Hitomebore', has been developed as a cultivar highly tolerant to low temperature at the booting stage. However, even 'Hitomebore' exhibits sterility at a temperature lower than 18.5 °C. Further improvement of cold tolerance of rice is required. In the present study, QTLs for cold tolerance in a Bhutanese rice variety, 'Kuchum', were analyzed using backcrossed progenies and a major QTL, named qCT-4, was detected on chromosome 4. Evaluating cold tolerance of seven types of near isogenic lines having 'Kuchum' alleles around qCT-4 with a 'Hitomebore' genetic background, qCT-4 was delimited to a region of ca. 1.36 Mb between DNA markers 9_1 and 10_13. Homozygous 'Kuchum' alleles at qCT-4 showed an effect of increasing seed fertility by ca. 10 % under cold-water treatment. Near isogenic lines of 'Hitomebore' having 'Silewah' alleles of Ctb1 and Ctb2 and a 'Hokkai PL9' allele of qCTB8 did not exhibit higher cold tolerance than that of 'Hitomebore'. On the other hand, a qLTB3 allele derived from a Chinese cultivar 'Lijiangxintuanheigu' increased cold tolerance of 'Hitomebore', and pyramiding of the qCT-4 allele and the qLTB3 allele further increased seed fertility under cold-water treatment. Since NILs of 'Hitomebore' with the 'Kuchum' allele of qCT-4 were highly similar to 'Hitomebore' in other agronomic traits, the qCT-4 allele is considered to be useful for developing a cold-tolerant cultivar.
authors.affiliation: Miyagi Prefectural Furukawa Agricultural Experiment Station, Osaki, Miyagi, 989-6227, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Endo
authors.affiliation: Miyagi Prefectural Furukawa Agricultural Experiment Station, Osaki, Miyagi, 989-6227, Japan.|Miyagi Pref. Northern Regional Promotion Office Kurihara Regional Office, Fujiki,Tsukidate, Kurihara, Miyagi, 987-2251, Japan.
authors.forename: Bunya
authors.initials: B
authors.lastname: Chiba
authors.affiliation: Miyagi Prefectural Furukawa Agricultural Experiment Station, Osaki, Miyagi, 989-6227, Japan.|Earthquake Reconstruction and Planning Department, Miyagi Prefectural Office, Honcho, Aoba-ku, Sendai, Miyagi, 980-8570, Japan.
authors.forename: Kensuke
authors.initials: K
authors.lastname: Wagatsuma
authors.affiliation: Miyagi Prefectural Furukawa Agricultural Experiment Station, Osaki, Miyagi, 989-6227, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Saeki
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Tsuyu
authors.initials: T
authors.lastname: Ando
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Ayahiko
authors.initials: A
authors.lastname: Shomura
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Tatsumi
authors.initials: T
authors.lastname: Mizubayashi
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Tadamasa
authors.initials: T
authors.lastname: Ueda
authors.affiliation: National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, 305-8602, Japan.
authors.forename: Toshio
authors.initials: T
authors.lastname: Yamamoto
authors.affiliation: Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai, Miyagi, 981-8555, Japan. nishio@bios.tohoku.ac.jp.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishio
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000483:Alleles; D001947:Breeding; D003080:Cold Temperature; D003433:Crosses, Genetic; D005819:Genetic Markers; D005838:Genotype; D012275:Oryza / Q000235:genetics*; D040641:Quantitative Trait Loci
chemical_list: D005819:Genetic Markers