Heavy genetic load associated with the subspecific differentiation of japonica rice (Oryza sativa ssp. japonica L.).
Genetic load in the genome of the model species, rice, was genetically dissected by mapping quantitative trait loci (QTLs) affecting the radiosensitivity of 226 recombinant inbred lines (RILs) to gamma-ray- and spaceflight-induced radiation. The parents and RILs varied considerably in their radiosensitivity to gamma-ray irradiation. A total of 28 QTLs affecting the two index traits, seedling height (SH) and seed fertility (SF), of radiosensitivity were identified. The japonica parent, Lemont, was much more sensitive to gamma-ray irradiation than the indica parent, Teqing, and its alleles at almost all QTLs were associated with increased radiosensitivity, suggesting a much higher genetic load in the japonica genome of rice. Six QTLs (QSh2a, QSh2b, QSh5a, QSh7, QSf3b, and QSf10b) were located in the genomic regions particularly sensitive to radiation and thus might represent possible 'mutation hot spots' in the japonica genome. Detailed characterization of these genomic regions may shed light on the evolution and subspecific differentiation of rice.
Xu
Jian-Long
JL
Institute of Crop Sciences/The National Key Facility for Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, 12 South Zhong-Guan-Cun Street, Beijing 100081, PR China.
Wang
Jun-Min
JM
Sun
Ye-Qing
YQ
Wei
Li-Jun
LJ
Luo
Rong-Ting
RT
Zhang
Ming-Xian
MX
Li
Zhi-Kang
ZK
D005075:Biological Evolution; D002874:Chromosome Mapping; D005720:Gamma Rays; D008040:Genetic Linkage; D018745:Genome, Plant; D007178:Inbreeding; D012275:Oryza / Q000033:anatomy & histology / Q000235:genetics* / Q000528:radiation effects; D051479:Plant Infertility / Q000235:genetics / Q000528:radiation effects; D040641:Quantitative Trait Loci