Fine mapping of a grain weight quantitative trait locus on rice chromosome 8 using near-isogenic lines derived from a cross between Oryza sativa and Oryza rufipogon.
A quantitative trait locus (QTL) for grain weight (GW) was detected near SSR marker RM210 on chromosome 8 in backcross populations derived from a cross between the Korean japonica cultivar Hwaseongbyeo and Oryza rufipogon (IRGC 105491). The O. rufipogon allele increased GW in the Hwaseongbyeo background despite the fact that O. rufipogon was the small-seeded parent. Using sister BC(3)F(3) near-isogenic lines (NILs), gw8.1 was validated and mapped to a 6.1 cM region in the interval between RM42 and RM210 (P < or = 0.0001). Substitution mapping with eight BC(3)F(4) sub-NILs further narrowed the interval containing gw8.1 to about 306.4 kb between markers RM23201.CNR151 and RM30000.CNR99. A yield trial using homozygous BC(3)F(4) sister sub-NILs and the Hwaseongbyeo recurrent parent indicated that the NIL carrying an O. rufipogon chromosome segment across the entire gw8.1 target region out-yielded its sister NIL (containing Hwaseongbyeo chromosome in the RM42-RM210 interval) by 9% (P=0.029). The higher-yielding NIL produced 19.3% more grain than the Hwaseongbyeo recurrent parent (P=0.018). Analysis of a BC(3)F(4) NIL indicated that the variation for GW is associated with variation in grain shape, specifically grain length. The locus, gw8.1 is of particular interest because of its independence from undesirable height and grain quality traits. SSR markers tightly linked to the GW QTL will facilitate cloning of the gene underlying this QTL as well as marker-assisted selection for variation in GW in an applied breeding program.
Xie
Xiaobo
X
Department of Agronomy, College of Agriculture and Life Sciences, Chungnam National University, Daejeon 305-764, Korea.
Song
Mi-Hee
MH
Jin
Fengxue
F
Ahn
Sang-Nag
SN
Suh
Jung-Pil
JP
Hwang
Hung-Goo
HG
McCouch
S R
SR
D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics*; D003433:Crosses, Genetic; D002523:Edible Grain / Q000378:metabolism*; D017343:Genes, Plant; D005819:Genetic Markers; D012275:Oryza / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D010641:Phenotype; D040641:Quantitative Trait Loci / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid
D005819:Genetic Markers